Adding upstream version 5.3.1.upstream/5.3.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

100 files changed, 28328 insertions, 0 deletions

diff --git a/lib/README.rst b/lib/README.rst
new file mode 100644
index 0000000..766634c
--- /dev/null
+++ b/lib/README.rst
@@ -0,0 +1,312 @@
+.. SPDX-License-Identifier: GPL-3.0-or-later
+
+*********************
+Knot Resolver library
+*********************
+
+Requirements
+============
+
+* libknot_ 2.0 (Knot DNS high-performance DNS library.)
+
+For users
+=========
+
+The library as described provides basic services for name resolution, which should cover the usage,
+examples are in the :ref:`resolve API <lib_api_rplan>` documentation.
+
+.. tip:: If you're migrating from ``getaddrinfo()``, see *"synchronous"* API, but the library offers iterative API as well to plug it into your event loop for example.
+
+.. _lib-layers:
+
+For developers
+==============
+
+The resolution process starts with the functions in :ref:`resolve.c <lib_api_rplan>`, they are responsible for:
+
+* reacting to state machine state (i.e. calling consume layers if we have an answer ready)
+* interacting with the library user (i.e. asking caller for I/O, accepting queries)
+* fetching assets needed by layers (i.e. zone cut)
+
+This is the *driver*. The driver is not meant to know *"how"* the query resolves, but rather *"when"* to execute *"what"*.
+
+.. image:: ../doc/resolution.png
+   :align: center
+
+On the other side are *layers*. They are responsible for dissecting the packets and informing the driver about the results. For example, a *produce* layer generates query, a *consume* layer validates answer.
+
+.. tip:: Layers are executed asynchronously by the driver. If you need some asset beforehand, you can signalize the driver using returning state or current query flags. For example, setting a flag ``AWAIT_CUT`` forces driver to fetch zone cut information before the packet is consumed; setting a ``RESOLVED`` flag makes it pop a query after the current set of layers is finished; returning ``FAIL`` state makes it fail current query.
+
+Layers can also change course of resolution, for example by appending additional queries.
+
+.. code-block:: lua
+
+	consume = function (state, req, answer)
+		if answer:qtype() == kres.type.NS then
+			local qry = req:push(answer:qname(), kres.type.SOA, kres.class.IN)
+			qry.flags.AWAIT_CUT = true
+		end
+		return state
+	end
+
+This **doesn't** block currently processed query, and the newly created sub-request will start as soon as driver finishes processing current. In some cases you might need to issue sub-request and process it **before** continuing with the current, i.e. validator may need a DNSKEY before it can validate signatures. In this case, layers can yield and resume afterwards.
+
+.. code-block:: lua
+
+	consume = function (state, req, answer)
+		if state == kres.YIELD then
+			print('continuing yielded layer')
+			return kres.DONE
+		else
+			if answer:qtype() == kres.type.NS then
+				local qry = req:push(answer:qname(), kres.type.SOA, kres.class.IN)
+				qry.flags.AWAIT_CUT = true
+				print('planned SOA query, yielding')
+				return kres.YIELD
+			end
+			return state
+		end
+	end
+
+The ``YIELD`` state is a bit special. When a layer returns it, it interrupts current walk through the layers. When the layer receives it,
+it means that it yielded before and now it is resumed. This is useful in a situation where you need a sub-request to determine whether current answer is valid or not.
+
+Writing layers
+==============
+
+.. warning::  FIXME: this dev-docs section is outdated!  Better see comments in files instead, for now.
+
+The resolver :ref:`library <lib_index>` leverages the processing API from the libknot to separate packet processing code into layers.
+
+.. note:: This is only crash-course in the library internals, see the resolver :ref:`library <lib_index>` documentation for the complete overview of the services.
+
+The library offers following services:
+
+- :ref:`Cache <lib_api_cache>` - MVCC cache interface for retrieving/storing resource records.
+- :ref:`Resolution plan <lib_api_rplan>` - Query resolution plan, a list of partial queries (with hierarchy) sent in order to satisfy original query. This contains information about the queries, nameserver choice, timing information, answer and its class.
+- :ref:`Nameservers <lib_api_nameservers>` - Reputation database of nameservers, this serves as an aid for nameserver choice.
+
+A processing layer is going to be called by the query resolution driver for each query,
+so you're going to work with :ref:`struct kr_request <lib_api_rplan>` as your per-query context.
+This structure contains pointers to resolution context, resolution plan and also the final answer.
+
+.. code-block:: c
+
+	int consume(kr_layer_t *ctx, knot_pkt_t *pkt)
+	{
+		struct kr_request *req = ctx->req;
+		struct kr_query *qry = req->current_query;
+	}
+
+This is only passive processing of the incoming answer. If you want to change the course of resolution, say satisfy a query from a local cache before the library issues a query to the nameserver, you can use states (see the :ref:`Static hints <mod-hints>` for example).
+
+.. code-block:: c
+
+	int produce(kr_layer_t *ctx, knot_pkt_t *pkt)
+	{
+		struct kr_request *req = ctx->req;
+		struct kr_query *qry = req->current_query;
+
+		/* Query can be satisfied locally. */
+		if (can_satisfy(qry)) {
+			/* This flag makes the resolver move the query
+			 * to the "resolved" list. */
+			qry->flags.RESOLVED = true;
+			return KR_STATE_DONE;
+		}
+
+		/* Pass-through. */
+		return ctx->state;
+	}
+
+It is possible to not only act during the query resolution, but also to view the complete resolution plan afterwards. This is useful for analysis-type tasks, or *"per answer"* hooks.
+
+.. code-block:: c
+
+	int finish(kr_layer_t *ctx)
+	{
+		struct kr_request *req = ctx->req;
+		struct kr_rplan *rplan = req->rplan;
+
+		/* Print the query sequence with start time. */
+		char qname_str[KNOT_DNAME_MAXLEN];
+		struct kr_query *qry = NULL
+		WALK_LIST(qry, rplan->resolved) {
+			knot_dname_to_str(qname_str, qry->sname, sizeof(qname_str));
+			printf("%s at %u\n", qname_str, qry->timestamp);
+		}
+
+		return ctx->state;
+	}
+
+APIs in Lua
+===========
+
+The APIs in Lua world try to mirror the C APIs using LuaJIT FFI, with several differences and enhancements.
+There is not comprehensive guide on the API yet, but you can have a look at the bindings_ file.
+
+Elementary types and constants
+------------------------------
+
+* States are directly in ``kres`` table, e.g. ``kres.YIELD, kres.CONSUME, kres.PRODUCE, kres.DONE, kres.FAIL``.
+* DNS classes are in ``kres.class`` table, e.g. ``kres.class.IN`` for Internet class.
+* DNS types are in  ``kres.type`` table, e.g. ``kres.type.AAAA`` for AAAA type.
+* DNS rcodes types are in ``kres.rcode`` table, e.g. ``kres.rcode.NOERROR``.
+* Packet sections (QUESTION, ANSWER, AUTHORITY, ADDITIONAL) are in the ``kres.section`` table.
+
+Working with domain names
+-------------------------
+
+The internal API usually works with domain names in label format, you can convert between text and wire freely.
+
+.. code-block:: lua
+
+	local dname = kres.str2dname('business.se')
+	local strname = kres.dname2str(dname)
+
+Working with resource records
+-----------------------------
+
+Resource records are stored as tables.
+
+.. code-block:: lua
+
+	local rr = { owner = kres.str2dname('owner'),
+	             ttl = 0,
+	             class = kres.class.IN,
+	             type = kres.type.CNAME,
+	             rdata = kres.str2dname('someplace') }
+	print(kres.rr2str(rr))
+
+RRSets in packet can be accessed using FFI, you can easily fetch single records.
+
+.. code-block:: lua
+
+	local rrset = { ... }
+	local rr = rrset:get(0) -- Return first RR
+	print(kres.dname2str(rr:owner()))
+	print(rr:ttl())
+	print(kres.rr2str(rr))
+
+Working with packets
+--------------------
+
+Packet is the data structure that you're going to see in layers very often. They consists of a header, and four sections: QUESTION, ANSWER, AUTHORITY, ADDITIONAL. The first section is special, as it contains the query name, type, and class; the rest of the sections contain RRSets.
+
+First you need to convert it to a type known to FFI and check basic properties. Let's start with a snippet of a *consume* layer.
+
+.. code-block:: lua
+
+	consume = function (state, req, pkt)
+		print('rcode:', pkt:rcode())
+		print('query:', kres.dname2str(pkt:qname()), pkt:qclass(), pkt:qtype())
+		if pkt:rcode() ~= kres.rcode.NOERROR then
+			print('error response')
+		end
+	end
+
+You can enumerate records in the sections.
+
+.. code-block:: lua
+
+	local records = pkt:section(kres.section.ANSWER)
+	for i = 1, #records do
+		local rr = records[i]
+		if rr.type == kres.type.AAAA then
+			print(kres.rr2str(rr))
+		end
+	end
+
+During *produce* or *begin*, you might want to want to write to packet. Keep in mind that you have to write packet sections in sequence,
+e.g. you can't write to ANSWER after writing AUTHORITY, it's like stages where you can't go back.
+
+.. code-block:: lua
+
+		pkt:rcode(kres.rcode.NXDOMAIN)
+		-- Clear answer and write QUESTION
+		pkt:recycle()
+		pkt:question('\7blocked', kres.class.IN, kres.type.SOA)
+		-- Start writing data
+		pkt:begin(kres.section.ANSWER)
+		-- Nothing in answer
+		pkt:begin(kres.section.AUTHORITY)
+		local soa = { owner = '\7blocked', ttl = 900, class = kres.class.IN, type = kres.type.SOA, rdata = '...' }
+		pkt:put(soa.owner, soa.ttl, soa.class, soa.type, soa.rdata)
+
+Working with requests
+---------------------
+
+The request holds information about currently processed query, enabled options, cache, and other extra data.
+You primarily need to retrieve currently processed query.
+
+.. code-block:: lua
+
+	consume = function (state, req, pkt)
+		print(req.options)
+		print(req.state)
+
+		-- Print information about current query
+		local current = req:current()
+		print(kres.dname2str(current.owner))
+		print(current.stype, current.sclass, current.id, current.flags)
+	end
+
+In layers that either begin or finalize, you can walk the list of resolved queries.
+
+.. code-block:: lua
+
+	local last = req:resolved()
+	print(last.stype)
+
+As described in the layers, you can not only retrieve information about current query, but also push new ones or pop old ones.
+
+.. code-block:: lua
+
+		-- Push new query
+		local qry = req:push(pkt:qname(), kres.type.SOA, kres.class.IN)
+		qry.flags.AWAIT_CUT = true
+
+		-- Pop the query, this will erase it from resolution plan
+		req:pop(qry)
+
+
+.. _libknot:  https://gitlab.nic.cz/knot/knot-dns/tree/master/src/libknot
+.. _bindings: https://gitlab.nic.cz/knot/knot-resolver/blob/master/daemon/lua/kres.lua
+
+
+.. _significant-lua-changes:
+
+Significant Lua API changes
+---------------------------
+
+Incompatible changes since 3.0.0
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+In the main ``kres.*`` lua binding, there was only change in struct knot_rrset_t:
+
+- constructor now accepts TTL as additional parameter (defaulting to zero)
+- add_rdata() doesn't accept TTL anymore (and will throw an error if passed)
+
+In case you used knot_* functions and structures bound to lua:
+
+- knot_dname_is_sub(a, b): knot_dname_in_bailiwick(a, b) > 0
+- knot_rdata_rdlen(): knot_rdataset_at().len
+- knot_rdata_data(): knot_rdataset_at().data
+- knot_rdata_array_size(): offsetof(struct knot_data_t, data) + knot_rdataset_at().len
+- struct knot_rdataset: field names were renamed to .count and .rdata
+- some functions got inlined from headers, but you can use their kr_* clones:
+  kr_rrsig_sig_inception(), kr_rrsig_sig_expiration(), kr_rrsig_type_covered().
+  Note that these functions now accept knot_rdata_t* instead of a pair
+  knot_rdataset_t* and size_t - you can use knot_rdataset_at() for that.
+
+- knot_rrset_add_rdata() doesn't take TTL parameter anymore
+- knot_rrset_init_empty() was inlined, but in lua you can use the constructor
+- knot_rrset_ttl() was inlined, but in lua you can use :ttl() method instead
+
+- knot_pkt_qname(), _qtype(), _qclass(), _rr(), _section() were inlined,
+  but in lua you can use methods instead, e.g. myPacket:qname()
+- knot_pkt_free() takes knot_pkt_t* instead of knot_pkt_t**, but from lua
+  you probably didn't want to use that; constructor ensures garbage collection.
+
+
+.. |---| unicode:: U+02014 .. em dash
diff --git a/lib/cache/README.rst b/lib/cache/README.rst
new file mode 100644
index 0000000..00c227a
--- /dev/null
+++ b/lib/cache/README.rst
@@ -0,0 +1,69 @@
+.. SPDX-License-Identifier: GPL-3.0-or-later
+
+.. _cache_sizing:
+
+Cache sizing
+------------
+
+For personal use-cases and small deployments cache size around 100 MB is more than enough.
+
+For large deployments we recommend to run Knot Resolver on a dedicated machine, and to allocate 90% of machine's free memory for resolver's cache.
+
+For example, imagine you have a machine with 16 GB of memory.
+After machine restart you use command ``free -m`` to determine amount of free memory (without swap):
+
+.. code-block:: bash
+
+  $ free -m
+                total        used        free
+  Mem:          15907         979       14928
+
+Now you can configure cache size to be 90% of the free memory 14 928 MB, i.e. 13 453 MB:
+
+.. code-block:: lua
+
+   -- 90 % of free memory after machine restart
+   cache.size = 13453 * MB
+
+.. _cache_persistence:
+
+Cache persistence
+-----------------
+.. tip:: Using tmpfs for cache improves performance and reduces disk I/O.
+
+By default the cache is saved on a persistent storage device
+so the content of the cache is persisted during system reboot.
+This usually leads to smaller latency after restart etc.,
+however in certain situations a non-persistent cache storage might be preferred, e.g.:
+
+  - Resolver handles high volume of queries and I/O performance to disk is too low.
+  - Threat model includes attacker getting access to disk content in power-off state.
+  - Disk has limited number of writes (e.g. flash memory in routers).
+
+If non-persistent cache is desired configure cache directory to be on
+tmpfs_ filesystem, a temporary in-memory file storage.
+The cache content will be saved in memory, and thus have faster access
+and will be lost on power-off or reboot.
+
+
+.. note:: In most of the Unix-like systems ``/tmp`` and ``/var/run`` are commonly mounted to tmpfs.
+   While it is technically possible to move the cache to an existing
+   tmpfs filesystem, it is *not recommended*: The path to cache is specified in
+   multiple systemd units, and a shared tmpfs space could be used up by other
+   applications, leading to ``SIGBUS`` errors during runtime.
+
+Mounting the cache directory as tmpfs_ is recommended apparoach.
+Make sure to use appropriate ``size=`` option and don't forget to adjust the
+size in the config file as well.
+
+.. code-block::
+
+   # /etc/fstab
+   tmpfs	/var/cache/knot-resolver	tmpfs	rw,size=2G,uid=knot-resolver,gid=knot-resolver,nosuid,nodev,noexec,mode=0700 0 0
+
+.. code-block:: lua
+
+   # /etc/knot-resolver/config
+   cache.size = 2 * GB
+
+.. _tmpfs: https://en.wikipedia.org/wiki/Tmpfs
diff --git a/lib/cache/api.c b/lib/cache/api.c
new file mode 100644
index 0000000..922149d
--- /dev/null
+++ b/lib/cache/api.c
@@ -0,0 +1,1021 @@
+/*  Copyright (C) 2014-2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#include <assert.h>
+#include <errno.h>
+#include <limits.h>
+#include <sys/stat.h>
+#include <sys/time.h>
+#include <time.h>
+#include <unistd.h>
+
+#include <libknot/descriptor.h>
+#include <libknot/dname.h>
+#include <libknot/errcode.h>
+#include <libknot/rrtype/rrsig.h>
+
+#include <uv.h>
+
+#include "contrib/base32hex.h"
+#include "contrib/cleanup.h"
+#include "contrib/ucw/lib.h"
+#include "lib/cache/api.h"
+#include "lib/cache/cdb_lmdb.h"
+#include "lib/defines.h"
+#include "lib/dnssec/nsec3.h"
+#include "lib/generic/trie.h"
+#include "lib/resolve.h"
+#include "lib/rplan.h"
+#include "lib/utils.h"
+
+#include "lib/cache/impl.h"
+
+/* TODO:
+ *	- Reconsider when RRSIGs are put in and retrieved from the cache.
+ *	  Currently it's always done, which _might_ be spurious, depending
+ *	  on how kresd will use the returned result.
+ *	  There's also the "problem" that kresd ATM does _not_ ask upstream
+ *	  with DO bit in some cases.
+ */
+
+
+/** Cache version */
+static const uint16_t CACHE_VERSION = 6;
+/** Key size */
+#define KEY_HSIZE (sizeof(uint8_t) + sizeof(uint16_t))
+#define KEY_SIZE (KEY_HSIZE + KNOT_DNAME_MAXLEN)
+
+
+/** @internal Forward declarations of the implementation details
+ * \param needs_pkt[out] optionally set *needs_pkt = true;
+ * 	We do that when some RRset wasn't stashed to aggressive cache,
+ * 	even though it might have taken part in a successful DNSSEC proof:
+ * 	1. any opt-out NSEC3, as they typically aren't much use aggressively anyway
+ * 	2. some kinds of minimal NSEC* ranges, as they'd seem more trouble than worth:
+ * 	    - extremely short range of covered names limits the benefits severly
+ * 	    - the type-set is often a lie, either a working lie, e.g. CloudFlare's
+ * 	      black lies, or even a non-working lie, e.g. DVE-2018-0003
+ * 	3. some kinds of "weird" RRsets, to get at least some caching on them
+ */
+static ssize_t stash_rrset(struct kr_cache *cache, const struct kr_query *qry,
+		const knot_rrset_t *rr, const knot_rrset_t *rr_sigs, uint32_t timestamp,
+		uint8_t rank, trie_t *nsec_pmap, bool *needs_pkt);
+/** Preliminary checks before stash_rrset().  Don't call if returns <= 0. */
+static int stash_rrset_precond(const knot_rrset_t *rr, const struct kr_query *qry/*logs*/);
+
+/** @internal Ensure the cache version is right, possibly by clearing it. */
+static int assert_right_version(struct kr_cache *cache)
+{
+	/* Check cache ABI version. */
+	/* CACHE_KEY_DEF: to avoid collisions with kr_cache_match(). */
+	uint8_t key_str[4] = "VERS";
+	knot_db_val_t key = { .data = key_str, .len = sizeof(key_str) };
+	knot_db_val_t val = { NULL, 0 };
+	int ret = cache_op(cache, read, &key, &val, 1);
+	if (ret == 0 && val.len == sizeof(CACHE_VERSION)
+	    && memcmp(val.data, &CACHE_VERSION, sizeof(CACHE_VERSION)) == 0) {
+		ret = kr_ok();
+	} else {
+		int oldret = ret;
+		/* Version doesn't match or we were unable to read it, possibly because DB is empty.
+		 * Recreate cache and write version key. */
+		ret = cache_op(cache, count);
+		if (ret != 0) { /* Log for non-empty cache to limit noise on fresh start. */
+			kr_log_info("[cache] incompatible cache database detected, purging\n");
+			if (oldret) {
+				kr_log_verbose("[cache] reading version returned: %d\n", oldret);
+			} else if (val.len != sizeof(CACHE_VERSION)) {
+				kr_log_verbose("[cache] version has bad length: %d\n", (int)val.len);
+			} else {
+				uint16_t ver;
+				memcpy(&ver, val.data, sizeof(ver));
+				kr_log_verbose("[cache] version has bad value: %d instead of %d\n",
+					(int)ver, (int)CACHE_VERSION);
+			}
+		}
+		ret = cache_op(cache, clear);
+	}
+	/* Rewrite the entry even if it isn't needed.  Because of cache-size-changing
+	 * possibility it's good to always perform some write during opening of cache. */
+	if (ret == 0) {
+		/* Key/Val is invalidated by cache purge, recreate it */
+		val.data = /*const-cast*/(void *)&CACHE_VERSION;
+		val.len = sizeof(CACHE_VERSION);
+		ret = cache_op(cache, write, &key, &val, 1);
+	}
+	kr_cache_commit(cache);
+	return ret;
+}
+
+int kr_cache_open(struct kr_cache *cache, const struct kr_cdb_api *api, struct kr_cdb_opts *opts, knot_mm_t *mm)
+{
+	if (!cache) {
+		assert(cache);
+		return kr_error(EINVAL);
+	}
+	memset(cache, 0, sizeof(*cache));
+	/* Open cache */
+	if (!api) {
+		api = kr_cdb_lmdb();
+	}
+	cache->api = api;
+	int ret = cache->api->open(&cache->db, &cache->stats, opts, mm);
+	if (ret == 0) {
+		ret = assert_right_version(cache);
+		// The included write also committed maxsize increase to the file.
+	}
+	if (ret == 0 && opts->maxsize) {
+		/* If some maxsize is requested and it's smaller than in-file maxsize,
+		 * LMDB only restricts our env without changing the in-file maxsize.
+		 * That is worked around by reopening (found no other reliable way). */
+		cache->api->close(cache->db, &cache->stats);
+		struct kr_cdb_opts opts2;
+		memcpy(&opts2, opts, sizeof(opts2));
+		opts2.maxsize = 0;
+		ret = cache->api->open(&cache->db, &cache->stats, &opts2, mm);
+	}
+
+	char *fpath = kr_absolutize_path(opts->path, "data.mdb");
+	if (fpath) {
+		kr_cache_emergency_file_to_remove = fpath;
+	} else {
+		assert(false); /* non-critical, but still */
+		fpath = "<ENOMEM>";
+	}
+
+	if (ret == 0 && opts->maxsize) {
+		size_t maxsize = cache->api->get_maxsize(cache->db);
+		if (maxsize > opts->maxsize) kr_log_info(
+			"[cache] Warning: real cache size is %zu instead of the requested %zu bytes."
+			"  To reduce the size you need to remove the file '%s' by hand.\n",
+			maxsize, opts->maxsize, fpath);
+	}
+	if (ret != 0) {
+		return ret;
+	}
+	cache->ttl_min = KR_CACHE_DEFAULT_TTL_MIN;
+	cache->ttl_max = KR_CACHE_DEFAULT_TTL_MAX;
+	kr_cache_make_checkpoint(cache);
+	return 0;
+}
+
+const char *kr_cache_emergency_file_to_remove = NULL;
+
+
+#define cache_isvalid(cache) ((cache) && (cache)->api && (cache)->db)
+
+void kr_cache_close(struct kr_cache *cache)
+{
+	kr_cache_check_health(cache, -1);
+	if (cache_isvalid(cache)) {
+		cache_op(cache, close);
+		cache->db = NULL;
+	}
+	free(/*const-cast*/(char*)kr_cache_emergency_file_to_remove);
+	kr_cache_emergency_file_to_remove = NULL;
+}
+
+int kr_cache_commit(struct kr_cache *cache)
+{
+	if (!cache_isvalid(cache)) {
+		return kr_error(EINVAL);
+	}
+	if (cache->api->commit) {
+		return cache_op(cache, commit);
+	}
+	return kr_ok();
+}
+
+int kr_cache_insert_rr(struct kr_cache *cache, const knot_rrset_t *rr, const knot_rrset_t *rrsig, uint8_t rank, uint32_t timestamp)
+{
+	int err = stash_rrset_precond(rr, NULL);
+	if (err <= 0) {
+		return kr_ok();
+	}
+	ssize_t written = stash_rrset(cache, NULL, rr, rrsig, timestamp, rank, NULL, NULL);
+		/* Zone's NSEC* params aren't updated, but that's probably OK
+		 * for kr_cache_insert_rr() */
+	if (written >= 0) {
+		return kr_ok();
+	}
+
+	return (int) written;
+}
+
+int kr_cache_clear(struct kr_cache *cache)
+{
+	if (!cache_isvalid(cache)) {
+		return kr_error(EINVAL);
+	}
+	int ret = cache_op(cache, clear);
+	if (ret == 0) {
+		kr_cache_make_checkpoint(cache);
+		ret = assert_right_version(cache);
+	}
+	return ret;
+}
+
+/* When going stricter, BEWARE of breaking entry_h_consistent_NSEC() */
+struct entry_h * entry_h_consistent_E(knot_db_val_t data, uint16_t type)
+{
+	(void) type; /* unused, for now */
+	if (!data.data) return NULL;
+	/* Length checks. */
+	if (data.len < offsetof(struct entry_h, data))
+		return NULL;
+	const struct entry_h *eh = data.data;
+	if (eh->is_packet) {
+		uint16_t pkt_len;
+		if (data.len < offsetof(struct entry_h, data) + sizeof(pkt_len)) {
+			return NULL;
+		}
+		memcpy(&pkt_len, eh->data, sizeof(pkt_len));
+		if (data.len < offsetof(struct entry_h, data) + sizeof(pkt_len)
+				+ pkt_len) {
+			return NULL;
+		}
+	}
+
+	bool ok = true;
+	ok = ok && kr_rank_check(eh->rank);
+	ok = ok && (!kr_rank_test(eh->rank, KR_RANK_BOGUS)
+		    || eh->is_packet);
+	ok = ok && (eh->is_packet || !eh->has_optout);
+
+	return ok ? /*const-cast*/(struct entry_h *)eh : NULL;
+}
+
+int32_t get_new_ttl(const struct entry_h *entry, const struct kr_query *qry,
+                    const knot_dname_t *owner, uint16_t type, uint32_t now)
+{
+	int32_t diff = now - entry->time;
+	if (diff < 0) {
+		/* We may have obtained the record *after* the request started. */
+		diff = 0;
+	}
+	int32_t res = entry->ttl - diff;
+	if (res < 0 && owner && qry && qry->stale_cb) {
+		/* Stale-serving decision, delegated to a callback. */
+		int res_stale = qry->stale_cb(res, owner, type, qry);
+		if (res_stale >= 0)
+			return res_stale;
+	}
+	return res;
+}
+
+int32_t kr_cache_ttl(const struct kr_cache_p *peek, const struct kr_query *qry,
+		     const knot_dname_t *name, uint16_t type)
+{
+	const struct entry_h *eh = peek->raw_data;
+	return get_new_ttl(eh, qry, name, type, qry->timestamp.tv_sec);
+}
+
+/** Check that no label contains a zero character, incl. a log trace.
+ *
+ * We refuse to work with those, as LF and our cache keys might become ambiguous.
+ * Assuming uncompressed name, as usual.
+ * CACHE_KEY_DEF
+ */
+static bool check_dname_for_lf(const knot_dname_t *n, const struct kr_query *qry/*logging*/)
+{
+	const bool ret = knot_dname_size(n) == strlen((const char *)n) + 1;
+	if (!ret) { WITH_VERBOSE(qry) {
+		auto_free char *n_str = kr_dname_text(n);
+		VERBOSE_MSG(qry, "=> skipping zero-containing name %s\n", n_str);
+	} }
+	return ret;
+}
+
+/** Return false on types to be ignored.  Meant both for sname and direct cache requests. */
+static bool check_rrtype(uint16_t type, const struct kr_query *qry/*logging*/)
+{
+	const bool ret = !knot_rrtype_is_metatype(type)
+			&& type != KNOT_RRTYPE_RRSIG;
+	if (!ret) { WITH_VERBOSE(qry) {
+		auto_free char *type_str = kr_rrtype_text(type);
+		VERBOSE_MSG(qry, "=> skipping RR type %s\n", type_str);
+	} }
+	return ret;
+}
+
+/** Like key_exact_type() but omits a couple checks not holding for pkt cache. */
+knot_db_val_t key_exact_type_maypkt(struct key *k, uint16_t type)
+{
+	assert(check_rrtype(type, NULL));
+	switch (type) {
+	case KNOT_RRTYPE_RRSIG: /* no RRSIG query caching, at least for now */
+		assert(false);
+		return (knot_db_val_t){ NULL, 0 };
+	/* xNAME lumped into NS. */
+	case KNOT_RRTYPE_CNAME:
+	case KNOT_RRTYPE_DNAME:
+		type = KNOT_RRTYPE_NS;
+	default:
+		break;
+	}
+
+	int name_len = k->buf[0];
+	k->buf[name_len + 1] = 0; /* make sure different names can never match */
+	k->buf[name_len + 2] = 'E'; /* tag for exact name+type matches */
+	memcpy(k->buf + name_len + 3, &type, 2);
+	k->type = type;
+	/* CACHE_KEY_DEF: key == dname_lf + '\0' + 'E' + RRTYPE */
+	return (knot_db_val_t){ k->buf + 1, name_len + 4 };
+}
+
+
+/** The inside for cache_peek(); implementation separated to ./peek.c */
+int peek_nosync(kr_layer_t *ctx, knot_pkt_t *pkt);
+/** function for .produce phase */
+int cache_peek(kr_layer_t *ctx, knot_pkt_t *pkt)
+{
+	struct kr_request *req = ctx->req;
+	struct kr_query *qry = req->current_query;
+	/* We first check various exit-conditions and then call the _real function. */
+
+	if (!kr_cache_is_open(&req->ctx->cache)
+	    || ctx->state & (KR_STATE_FAIL|KR_STATE_DONE) || qry->flags.NO_CACHE
+	    || (qry->flags.CACHE_TRIED && !qry->stale_cb)
+	    || !check_rrtype(qry->stype, qry) /* LATER: some other behavior for some of these? */
+	    || qry->sclass != KNOT_CLASS_IN) {
+		return ctx->state; /* Already resolved/failed or already tried, etc. */
+	}
+	/* ATM cache only peeks for qry->sname and that would be useless
+	 * to repeat on every iteration, so disable it from now on.
+	 * LATER(optim.): assist with more precise QNAME minimization. */
+	qry->flags.CACHE_TRIED = true;
+
+	if (qry->stype == KNOT_RRTYPE_NSEC) {
+		VERBOSE_MSG(qry, "=> skipping stype NSEC\n");
+		return ctx->state;
+	}
+	if (!check_dname_for_lf(qry->sname, qry)) {
+		return ctx->state;
+	}
+
+	int ret = peek_nosync(ctx, pkt);
+	kr_cache_commit(&req->ctx->cache);
+	return ret;
+}
+
+
+
+/** It's simply inside of cycle taken out to decrease indentation.  \return error code. */
+static int stash_rrarray_entry(ranked_rr_array_t *arr, int arr_i,
+			const struct kr_query *qry, struct kr_cache *cache,
+			int *unauth_cnt, trie_t *nsec_pmap, bool *needs_pkt);
+/** Stash a single nsec_p.  \return 0 (errors are ignored). */
+static int stash_nsec_p(const knot_dname_t *dname, const char *nsec_p_v,
+			struct kr_request *req);
+
+/** The whole .consume phase for the cache module. */
+int cache_stash(kr_layer_t *ctx, knot_pkt_t *pkt)
+{
+	struct kr_request *req = ctx->req;
+	struct kr_query *qry = req->current_query;
+	struct kr_cache *cache = &req->ctx->cache;
+
+	/* Note: we cache even in KR_STATE_FAIL.  For example,
+	 * BOGUS answer can go to +cd cache even without +cd request. */
+	if (!kr_cache_is_open(cache) || !qry
+	    || qry->flags.CACHED || !check_rrtype(knot_pkt_qtype(pkt), qry)
+	    || qry->sclass != KNOT_CLASS_IN) {
+		return ctx->state;
+	}
+	/* Do not cache truncated answers, at least for now.  LATER */
+	if (knot_wire_get_tc(pkt->wire)) {
+		return ctx->state;
+	}
+	int unauth_cnt = 0;
+	bool needs_pkt = false;
+	if (qry->flags.STUB) {
+		needs_pkt = true;
+		goto stash_packet;
+	}
+
+	/* Stash individual records. */
+	ranked_rr_array_t *selected[] = kr_request_selected(req);
+	trie_t *nsec_pmap = trie_create(&req->pool);
+	if (!nsec_pmap) {
+		assert(!ENOMEM);
+		goto finally;
+	}
+	for (int psec = KNOT_ANSWER; psec <= KNOT_ADDITIONAL; ++psec) {
+		ranked_rr_array_t *arr = selected[psec];
+		/* uncached entries are located at the end */
+		for (ssize_t i = arr->len - 1; i >= 0; --i) {
+			ranked_rr_array_entry_t *entry = arr->at[i];
+			if (entry->qry_uid != qry->uid || entry->dont_cache) {
+				continue;
+				/* TODO: probably safe to break on uid mismatch but maybe not worth it */
+			}
+			int ret = stash_rrarray_entry(
+					arr, i, qry, cache, &unauth_cnt, nsec_pmap,
+					/* ADDITIONAL RRs are considered non-essential
+					 * in our (resolver) answers */
+					(psec == KNOT_ADDITIONAL ? NULL : &needs_pkt));
+			if (ret) {
+				VERBOSE_MSG(qry, "=> stashing RRs errored out\n");
+				goto finally;
+			}
+			/* LATER(optim.): maybe filter out some type-rank combinations
+			 * that won't be useful as separate RRsets. */
+		}
+	}
+
+	trie_it_t *it;
+	for (it = trie_it_begin(nsec_pmap); !trie_it_finished(it); trie_it_next(it)) {
+		stash_nsec_p((const knot_dname_t *)trie_it_key(it, NULL),
+				(const char *)*trie_it_val(it), req);
+	}
+	trie_it_free(it);
+	/* LATER(optim.): typically we also have corresponding NS record in the list,
+	 * so we might save a cache operation. */
+stash_packet:
+	if (qry->flags.PKT_IS_SANE && check_dname_for_lf(knot_pkt_qname(pkt), qry)) {
+		stash_pkt(pkt, qry, req, needs_pkt);
+	}
+
+finally:
+	if (unauth_cnt) {
+		VERBOSE_MSG(qry, "=> stashed also %d nonauth RRsets\n", unauth_cnt);
+	};
+	kr_cache_commit(cache);
+	return ctx->state; /* we ignore cache-stashing errors */
+}
+
+/** Preliminary checks before stash_rrset().  Don't call if returns <= 0. */
+static int stash_rrset_precond(const knot_rrset_t *rr, const struct kr_query *qry/*logs*/)
+{
+	if (!rr || rr->rclass != KNOT_CLASS_IN) {
+		assert(!EINVAL);
+		return kr_error(EINVAL);
+	}
+	if (!check_rrtype(rr->type, qry)) {
+		return kr_ok();
+	}
+	if (!check_dname_for_lf(rr->owner, qry)) {
+		return kr_ok();
+	}
+	return 1/*proceed*/;
+}
+
+/** Return true on some cases of NSEC* RRsets covering minimal ranges.
+ * Also include some abnormal RR cases; qry is just for logging. */
+static bool rrset_has_min_range_or_weird(const knot_rrset_t *rr, const struct kr_query *qry)
+{
+	if (!rr->rrs.count) {
+		assert(!EINVAL);
+		return true; /*< weird */
+	}
+	bool ret; /**< NOT used for the weird cases */
+	if (rr->type == KNOT_RRTYPE_NSEC) {
+		/* NSEC: name -> \000.name
+		 * Note: we have to lower-case it; the reasons are better explained
+		 * on other knot_nsec_next() call sites. */
+		knot_dname_t next[KNOT_DNAME_MAXLEN];
+		if (knot_dname_to_wire(next, knot_nsec_next(rr->rrs.rdata), sizeof(next)) < 0)
+			return true; /*< weird */
+		knot_dname_to_lower(next);
+		ret = next[0] == '\1' && next[1] == '\0'
+			&& knot_dname_is_equal(next + 2, rr->owner);
+	} else if (rr->type == KNOT_RRTYPE_NSEC3) {
+		if (knot_nsec3_next_len(rr->rrs.rdata) != NSEC3_HASH_LEN
+		    || *rr->owner != NSEC3_HASH_TXT_LEN) {
+			return true; /*< weird */
+		}
+		/* Let's work on the binary hashes.  Find if they "differ by one",
+		 * by constructing the owner hash incremented by one and comparing. */
+		uint8_t owner_hash[NSEC3_HASH_LEN];
+		if (base32hex_decode(rr->owner + 1, NSEC3_HASH_TXT_LEN,
+					owner_hash, NSEC3_HASH_LEN) != NSEC3_HASH_LEN) {
+			return true; /*< weird */
+		}
+		for (int i = NSEC3_HASH_LEN - 1; i >= 0; --i) {
+			if (++owner_hash[i] != 0) break;
+		}
+		const uint8_t *next_hash = knot_nsec3_next(rr->rrs.rdata);
+		ret = memcmp(owner_hash, next_hash, NSEC3_HASH_LEN) == 0;
+	} else {
+		return false;
+	}
+	if (ret) VERBOSE_MSG(qry, "=> minimized NSEC* range detected\n");
+	return ret;
+}
+
+static ssize_t stash_rrset(struct kr_cache *cache, const struct kr_query *qry,
+		const knot_rrset_t *rr, const knot_rrset_t *rr_sigs, uint32_t timestamp,
+		uint8_t rank, trie_t *nsec_pmap, bool *needs_pkt)
+{
+	if (kr_rank_test(rank, KR_RANK_BOGUS)) {
+		WITH_VERBOSE(qry) {
+			auto_free char *type_str = kr_rrtype_text(rr->type);
+			VERBOSE_MSG(qry, "=> skipping bogus RR set %s\n", type_str);
+		}
+		return kr_ok();
+	}
+	if (rr->type == KNOT_RRTYPE_NSEC3 && rr->rrs.count
+	    && knot_nsec3_iters(rr->rrs.rdata) > KR_NSEC3_MAX_ITERATIONS) {
+		/* This shouldn't happen often, thanks to downgrades during validation. */
+		VERBOSE_MSG(qry, "=> skipping NSEC3 with too many iterations\n");
+		return kr_ok();
+	}
+
+	assert(stash_rrset_precond(rr, qry) > 0);
+	if (!cache) {
+		assert(!EINVAL);
+		return kr_error(EINVAL);
+	}
+
+	int ret = kr_ok();
+	if (rrset_has_min_range_or_weird(rr, qry))
+		goto return_needs_pkt;
+	const int wild_labels = rr_sigs == NULL ? 0 :
+	       knot_dname_labels(rr->owner, NULL) - knot_rrsig_labels(rr_sigs->rrs.rdata);
+	if (wild_labels < 0)
+		goto return_needs_pkt;
+	const knot_dname_t *encloser = rr->owner; /**< the closest encloser name */
+	for (int i = 0; i < wild_labels; ++i) {
+		encloser = knot_wire_next_label(encloser, NULL);
+	}
+
+	/* Construct the key under which RRs will be stored,
+	 * and add corresponding nsec_pmap item (if necessary). */
+	struct key k_storage, *k = &k_storage;
+	knot_db_val_t key;
+	switch (rr->type) {
+	case KNOT_RRTYPE_NSEC3:
+		/* Skip opt-out NSEC3 sets. */
+		if (KNOT_NSEC3_FLAG_OPT_OUT & knot_nsec3_flags(rr->rrs.rdata))
+			goto return_needs_pkt;
+		/* fall through */
+	case KNOT_RRTYPE_NSEC:
+		/* Skip any NSEC*s that aren't validated or are suspicious. */
+		if (!kr_rank_test(rank, KR_RANK_SECURE) || rr->rrs.count != 1)
+			goto return_needs_pkt;
+		if (!rr_sigs || !rr_sigs->rrs.count || !rr_sigs->rrs.rdata) {
+			assert(!EINVAL);
+			ret = kr_error(EINVAL);
+			goto return_needs_pkt;
+		}
+		const knot_dname_t *signer = knot_rrsig_signer_name(rr_sigs->rrs.rdata);
+		const int signer_size = knot_dname_size(signer);
+		k->zlf_len = signer_size - 1;
+
+		void **npp = nsec_pmap == NULL ? NULL
+			: trie_get_ins(nsec_pmap, (const char *)signer, signer_size);
+		assert(!nsec_pmap || (npp && ENOMEM));
+		if (rr->type == KNOT_RRTYPE_NSEC) {
+			key = key_NSEC1(k, encloser, wild_labels);
+			break;
+		}
+
+		assert(rr->type == KNOT_RRTYPE_NSEC3);
+		const knot_rdata_t * const rdata = rr->rrs.rdata;
+		if (rdata->len <= 4) {
+			ret = kr_error(EILSEQ); /*< data from outside; less trust */
+			goto return_needs_pkt;
+		}
+		const int np_dlen = nsec_p_rdlen(rdata->data);
+		if (np_dlen > rdata->len) {
+			ret = kr_error(EILSEQ);
+			goto return_needs_pkt;
+		}
+		key = key_NSEC3(k, encloser, nsec_p_mkHash(rdata->data));
+		if (npp && !*npp) {
+			*npp = mm_alloc(&qry->request->pool, np_dlen);
+			if (!*npp) {
+				assert(!ENOMEM);
+				break;
+			}
+			memcpy(*npp, rdata->data, np_dlen);
+		}
+		break;
+	default:
+		ret = kr_dname_lf(k->buf, encloser, wild_labels);
+		if (ret) {
+			assert(!ret);
+			goto return_needs_pkt;
+		}
+		key = key_exact_type(k, rr->type);
+	}
+
+	/* Compute in-cache size for the new data. */
+	const knot_rdataset_t *rds_sigs = rr_sigs ? &rr_sigs->rrs : NULL;
+	const int rr_ssize = rdataset_dematerialize_size(&rr->rrs);
+	assert(rr_ssize == to_even(rr_ssize));
+	knot_db_val_t val_new_entry = {
+		.data = NULL,
+		.len = offsetof(struct entry_h, data) + rr_ssize
+			+ rdataset_dematerialize_size(rds_sigs),
+	};
+
+	/* Prepare raw memory for the new entry. */
+	ret = entry_h_splice(&val_new_entry, rank, key, k->type, rr->type,
+				rr->owner, qry, cache, timestamp);
+	if (ret) return kr_ok(); /* some aren't really errors */
+	assert(val_new_entry.data);
+
+	const uint32_t ttl = rr->ttl;
+	/* FIXME: consider TTLs and expirations of RRSIGs as well, just in case. */
+
+	/* Write the entry itself. */
+	struct entry_h *eh = val_new_entry.data;
+	memset(eh, 0, offsetof(struct entry_h, data));
+	eh->time = timestamp;
+	eh->ttl  = MAX(MIN(ttl, cache->ttl_max), cache->ttl_min);
+	eh->rank = rank;
+	if (rdataset_dematerialize(&rr->rrs, eh->data)
+	    || rdataset_dematerialize(rds_sigs, eh->data + rr_ssize)) {
+		/* minimize the damage from incomplete write; TODO: better */
+		eh->time = 0;
+		eh->ttl = 0;
+		eh->rank = 0;
+		assert(false);
+	}
+	assert(entry_h_consistent_E(val_new_entry, rr->type));
+
+	#if 0 /* Occasionally useful when debugging some kinds of changes. */
+	{
+	kr_cache_commit(cache);
+	knot_db_val_t val = { NULL, 0 };
+	ret = cache_op(cache, read, &key, &val, 1);
+	if (ret != kr_error(ENOENT)) { // ENOENT might happen in some edge case, I guess
+		assert(!ret);
+		entry_list_t el;
+		entry_list_parse(val, el);
+	}
+	}
+	#endif
+
+	/* Verbose-log some not-too-common cases. */
+	WITH_VERBOSE(qry) { if (kr_rank_test(rank, KR_RANK_AUTH)
+				|| rr->type == KNOT_RRTYPE_NS) {
+		auto_free char *type_str = kr_rrtype_text(rr->type),
+			*encl_str = kr_dname_text(encloser);
+		VERBOSE_MSG(qry, "=> stashed %s%s %s, rank 0%.2o, "
+			"%d B total, incl. %d RRSIGs\n",
+			(wild_labels ? "*." : ""), encl_str, type_str, rank,
+			(int)val_new_entry.len, (rr_sigs ? rr_sigs->rrs.count : 0)
+			);
+	} }
+
+	return (ssize_t) val_new_entry.len;
+return_needs_pkt:
+	if (needs_pkt) *needs_pkt = true;
+	return ret;
+}
+
+static int stash_rrarray_entry(ranked_rr_array_t *arr, int arr_i,
+			const struct kr_query *qry, struct kr_cache *cache,
+			int *unauth_cnt, trie_t *nsec_pmap, bool *needs_pkt)
+{
+	ranked_rr_array_entry_t *entry = arr->at[arr_i];
+	if (entry->cached) {
+		return kr_ok();
+	}
+	const knot_rrset_t *rr = entry->rr;
+	if (rr->type == KNOT_RRTYPE_RRSIG) {
+		return kr_ok(); /* reduce verbose logging from the following call */
+	}
+	int ret = stash_rrset_precond(rr, qry);
+	if (ret <= 0) {
+		return ret;
+	}
+
+	/* Try to find corresponding signatures, always.  LATER(optim.): speed. */
+	ranked_rr_array_entry_t *entry_rrsigs = NULL;
+	const knot_rrset_t *rr_sigs = NULL;
+	for (ssize_t j = arr->len - 1; j >= 0; --j) {
+		/* TODO: ATM we assume that some properties are the same
+		 * for all RRSIGs in the set (esp. label count). */
+		ranked_rr_array_entry_t *e = arr->at[j];
+		assert(!e->in_progress);
+		bool ok = e->qry_uid == qry->uid && !e->cached
+			&& e->rr->type == KNOT_RRTYPE_RRSIG
+			&& knot_rrsig_type_covered(e->rr->rrs.rdata) == rr->type
+			&& knot_dname_is_equal(rr->owner, e->rr->owner);
+		if (!ok) continue;
+		entry_rrsigs = e;
+		rr_sigs = e->rr;
+		break;
+	}
+
+	ssize_t written = stash_rrset(cache, qry, rr, rr_sigs, qry->timestamp.tv_sec,
+					entry->rank, nsec_pmap, needs_pkt);
+	if (written < 0) {
+		kr_log_error("[%05u.%02u][cach] stash failed, ret = %d\n", qry->request->uid,
+			     qry->uid, ret);
+		return (int) written;
+	}
+
+	if (written > 0) {
+		/* Mark entry as cached for the rest of the query processing */
+		entry->cached = true;
+		if (entry_rrsigs) {
+			entry_rrsigs->cached = true;
+		}
+		if (!kr_rank_test(entry->rank, KR_RANK_AUTH) && rr->type != KNOT_RRTYPE_NS) {
+			*unauth_cnt += 1;
+		}
+	}
+
+	return kr_ok();
+}
+
+static int stash_nsec_p(const knot_dname_t *dname, const char *nsec_p_v,
+			struct kr_request *req)
+{
+	const struct kr_query *qry = req->current_query;
+	struct kr_cache *cache = &req->ctx->cache;
+	uint32_t valid_until = qry->timestamp.tv_sec + cache->ttl_max;
+		/* LATER(optim.): be more precise here ^^ and reduce calls. */
+	static const int32_t ttl_margin = 3600;
+	const uint8_t *nsec_p = (const uint8_t *)nsec_p_v;
+	int data_stride = sizeof(valid_until) + nsec_p_rdlen(nsec_p);
+
+	unsigned int log_hash = 0xFeeeFeee; /* this type is simpler for printf args */
+	auto_free char *log_dname = NULL;
+	WITH_VERBOSE(qry) {
+		log_hash = nsec_p_v ? nsec_p_mkHash((const uint8_t *)nsec_p_v) : 0;
+		log_dname = kr_dname_text(dname);
+	}
+	/* Find what's in the cache. */
+	struct key k_storage, *k = &k_storage;
+	int ret = kr_dname_lf(k->buf, dname, false);
+	if (ret) return kr_error(ret);
+	knot_db_val_t key = key_exact_type(k, KNOT_RRTYPE_NS);
+	knot_db_val_t val_orig = { NULL, 0 };
+	ret = cache_op(cache, read, &key, &val_orig, 1);
+	if (ret && ret != -ABS(ENOENT)) {
+		VERBOSE_MSG(qry, "=> EL read failed (ret: %d)\n", ret);
+		return kr_ok();
+	}
+	/* Prepare new entry_list_t so we can just write at el[0]. */
+	entry_list_t el;
+	int log_refresh_by = 0;
+	if (ret == -ABS(ENOENT)) {
+		memset(el, 0, sizeof(el));
+	} else {
+		ret = entry_list_parse(val_orig, el);
+		if (ret) {
+			VERBOSE_MSG(qry, "=> EL parse failed (ret: %d)\n", ret);
+			return kr_error(0);
+		}
+		/* Find the index to replace. */
+		int i_replace = ENTRY_APEX_NSECS_CNT - 1;
+		for (int i = 0; i < ENTRY_APEX_NSECS_CNT; ++i) {
+			if (el[i].len != data_stride) continue;
+			if (nsec_p && memcmp(nsec_p, (uint8_t *)el[i].data + sizeof(uint32_t),
+						data_stride - sizeof(uint32_t)) != 0) {
+				continue;
+			}
+			/* Save a cache operation if TTL extended only a little. */
+			uint32_t valid_orig;
+			memcpy(&valid_orig, el[i].data, sizeof(valid_orig));
+			const int32_t ttl_extended_by = valid_until - valid_orig;
+			if (ttl_extended_by < ttl_margin) {
+				VERBOSE_MSG(qry,
+					"=> nsec_p stash for %s skipped (extra TTL: %d, hash: %x)\n",
+					log_dname, ttl_extended_by, log_hash);
+				return kr_ok();
+			}
+			i_replace = i;
+			log_refresh_by = ttl_extended_by;
+			break;
+		}
+		/* Shift the other indices: move the first `i_replace` blocks
+		 * by one position. */
+		if (i_replace) {
+			memmove(&el[1], &el[0], sizeof(el[0]) * i_replace);
+		}
+	}
+	/* Prepare old data into a buffer.  See entry_h_splice() for why.  LATER(optim.) */
+	el[0].len = data_stride;
+	el[0].data = NULL;
+	knot_db_val_t val;
+	val.len = entry_list_serial_size(el),
+	val.data = mm_alloc(&req->pool, val.len),
+	entry_list_memcpy(val.data, el);
+	/* Prepare the new data chunk */
+	memcpy(el[0].data, &valid_until, sizeof(valid_until));
+	if (nsec_p) {
+		memcpy((uint8_t *)el[0].data + sizeof(valid_until), nsec_p,
+			data_stride - sizeof(valid_until));
+	}
+	/* Write it all to the cache */
+	ret = cache_op(cache, write, &key, &val, 1);
+	if (ret || !val.data) {
+		VERBOSE_MSG(qry, "=> EL write failed (ret: %d)\n", ret);
+		return kr_ok();
+	}
+	if (log_refresh_by) {
+		VERBOSE_MSG(qry, "=> nsec_p stashed for %s (refresh by %d, hash: %x)\n",
+				log_dname, log_refresh_by, log_hash);
+	} else {
+		VERBOSE_MSG(qry, "=> nsec_p stashed for %s (new, hash: %x)\n",
+				log_dname, log_hash);
+	}
+	return kr_ok();
+}
+
+
+static int peek_exact_real(struct kr_cache *cache, const knot_dname_t *name, uint16_t type,
+			struct kr_cache_p *peek)
+{
+	if (!check_rrtype(type, NULL) || !check_dname_for_lf(name, NULL)) {
+		return kr_error(ENOTSUP);
+	}
+	struct key k_storage, *k = &k_storage;
+
+	int ret = kr_dname_lf(k->buf, name, false);
+	if (ret) return kr_error(ret);
+
+	knot_db_val_t key = key_exact_type(k, type);
+	knot_db_val_t val = { NULL, 0 };
+	ret = cache_op(cache, read, &key, &val, 1);
+	if (!ret) ret = entry_h_seek(&val, type);
+	if (ret) return kr_error(ret);
+
+	const struct entry_h *eh = entry_h_consistent_E(val, type);
+	if (!eh || eh->is_packet) {
+		// TODO: no packets, but better get rid of whole kr_cache_peek_exact().
+		return kr_error(ENOENT);
+	}
+	*peek = (struct kr_cache_p){
+		.time = eh->time,
+		.ttl  = eh->ttl,
+		.rank = eh->rank,
+		.raw_data = val.data,
+		.raw_bound = knot_db_val_bound(val),
+	};
+	return kr_ok();
+}
+int kr_cache_peek_exact(struct kr_cache *cache, const knot_dname_t *name, uint16_t type,
+			struct kr_cache_p *peek)
+{	/* Just wrap with extra verbose logging. */
+	const int ret = peek_exact_real(cache, name, type, peek);
+	if (false && VERBOSE_STATUS) { /* too noisy for usual --verbose */
+		auto_free char *type_str = kr_rrtype_text(type),
+			*name_str = kr_dname_text(name);
+		const char *result_str = (ret == kr_ok() ? "hit" :
+				(ret == kr_error(ENOENT) ? "miss" : "error"));
+		VERBOSE_MSG(NULL, "_peek_exact: %s %s %s (ret: %d)",
+				type_str, name_str, result_str, ret);
+	}
+	return ret;
+}
+
+int kr_cache_remove(struct kr_cache *cache, const knot_dname_t *name, uint16_t type)
+{
+	if (!cache_isvalid(cache)) {
+		return kr_error(EINVAL);
+	}
+	if (!cache->api->remove) {
+		return kr_error(ENOSYS);
+	}
+	struct key k_storage, *k = &k_storage;
+	int ret = kr_dname_lf(k->buf, name, false);
+	if (ret) return kr_error(ret);
+
+	knot_db_val_t key = key_exact_type(k, type);
+	return cache_op(cache, remove, &key, 1);
+}
+
+int kr_cache_match(struct kr_cache *cache, const knot_dname_t *name,
+		   bool exact_name, knot_db_val_t keyval[][2], int maxcount)
+{
+	if (!cache_isvalid(cache)) {
+		return kr_error(EINVAL);
+	}
+	if (!cache->api->match) {
+		return kr_error(ENOSYS);
+	}
+
+	struct key k_storage, *k = &k_storage;
+
+	int ret = kr_dname_lf(k->buf, name, false);
+	if (ret) return kr_error(ret);
+
+	// use a mock type
+	knot_db_val_t key = key_exact_type(k, KNOT_RRTYPE_A);
+	/* CACHE_KEY_DEF */
+	key.len -= sizeof(uint16_t); /* the type */
+	if (!exact_name) {
+		key.len -= 2; /* '\0' 'E' */
+		if (name[0] == '\0') ++key.len; /* the root name is special ATM */
+	}
+	return cache_op(cache, match, &key, keyval, maxcount);
+}
+
+int kr_unpack_cache_key(knot_db_val_t key, knot_dname_t *buf, uint16_t *type)
+{
+	if (key.data == NULL || buf == NULL || type == NULL) {
+		return kr_error(EINVAL);
+	}
+
+	int len = -1;
+	const char *tag, *key_data = key.data;
+	for (tag = key_data + 1; tag < key_data + key.len; ++tag) {
+		/* CACHE_KEY_DEF */
+		if (tag[-1] == '\0' && (tag == key_data + 1 || tag[-2] == '\0')) {
+			if (tag[0] != 'E') return kr_error(EINVAL);
+			len = tag - 1 - key_data;
+			break;
+		}
+	}
+
+	if (len == -1 || len > KNOT_DNAME_MAXLEN) {
+		return kr_error(EINVAL);
+	}
+
+	int ret = knot_dname_lf2wire(buf, len, key.data);
+	if (ret < 0) {
+		return kr_error(ret);
+	}
+
+	/* CACHE_KEY_DEF: jump over "\0 E/1" */
+	memcpy(type, tag + 1, sizeof(uint16_t));
+
+	return kr_ok();
+}
+
+
+int kr_cache_remove_subtree(struct kr_cache *cache, const knot_dname_t *name,
+			    bool exact_name, int maxcount)
+{
+	if (!cache_isvalid(cache)) {
+		return kr_error(EINVAL);
+	}
+
+	knot_db_val_t keyval[maxcount][2], keys[maxcount];
+	int ret = kr_cache_match(cache, name, exact_name, keyval, maxcount);
+	if (ret <= 0) { /* ENOENT -> nothing to remove */
+		return (ret == KNOT_ENOENT) ? 0 : ret;
+	}
+	const int count = ret;
+	/* Duplicate the key strings, as deletion may invalidate the pointers. */
+	int i;
+	for (i = 0; i < count; ++i) {
+		keys[i].len = keyval[i][0].len;
+		keys[i].data = malloc(keys[i].len);
+		if (!keys[i].data) {
+			ret = kr_error(ENOMEM);
+			goto cleanup;
+		}
+		memcpy(keys[i].data, keyval[i][0].data, keys[i].len);
+	}
+	ret = cache_op(cache, remove, keys, count);
+cleanup:
+	kr_cache_commit(cache); /* Sync even after just kr_cache_match(). */
+	/* Free keys */
+	while (--i >= 0) {
+		free(keys[i].data);
+	}
+	return ret;
+}
+
+static void health_timer_cb(uv_timer_t *health_timer)
+{
+	struct kr_cache *cache = health_timer->data;
+	if (cache)
+		cache_op(cache, check_health);
+	/* We don't do anything with the return code.  For example, in some situations
+	 * the file may not exist (temporarily), and we just expect to be more lucky
+	 * when the timer fires again. */
+}
+
+int kr_cache_check_health(struct kr_cache *cache, int interval)
+{
+	if (interval == 0) {
+		return cache_op(cache, check_health);
+	}
+	if (interval < 0) {
+		if (!cache->health_timer)
+			return kr_ok(); // tolerate stopping a "stopped" timer
+		uv_close((uv_handle_t *)cache->health_timer, (uv_close_cb)free);
+		cache->health_timer->data = NULL;
+		cache->health_timer = NULL;
+		return kr_ok();
+	}
+
+	assert(interval > 0);
+	if (!cache->health_timer) {
+		/* We avoid depending on daemon's symbols by using uv_default_loop. */
+		cache->health_timer = malloc(sizeof(*cache->health_timer));
+		if (!cache->health_timer) return kr_error(ENOMEM);
+		uv_loop_t *loop = uv_default_loop();
+		assert(loop);
+		int ret = uv_timer_init(loop, cache->health_timer);
+		if (ret) {
+			free(cache->health_timer);
+			cache->health_timer = NULL;
+			return kr_error(ret);
+		}
+		cache->health_timer->data = cache;
+	}
+	assert(cache->health_timer->data);
+	return kr_error(uv_timer_start(cache->health_timer, health_timer_cb, interval, interval));
+}
+
diff --git a/lib/cache/api.h b/lib/cache/api.h
new file mode 100644
index 0000000..28b3eb6
--- /dev/null
+++ b/lib/cache/api.h
@@ -0,0 +1,193 @@
+/*  Copyright (C) 2014-2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#pragma once
+
+#include <libknot/consts.h>
+#include <libknot/rrset.h>
+#include <sys/time.h>
+#include "lib/cache/cdb_api.h"
+#include "lib/defines.h"
+#include "contrib/ucw/config.h" /*uint*/
+
+/** When knot_pkt is passed from cache without ->wire, this is the ->size. */
+static const size_t PKT_SIZE_NOWIRE = -1;
+
+
+#include "lib/module.h"
+/* Prototypes for the 'cache' module implementation. */
+int cache_peek(kr_layer_t *ctx, knot_pkt_t *pkt);
+int cache_stash(kr_layer_t *ctx, knot_pkt_t *pkt);
+
+
+/**
+ * Cache structure, keeps API, instance and metadata.
+ */
+struct kr_cache
+{
+	kr_cdb_pt db;                 /**< Storage instance */
+	const struct kr_cdb_api *api; /**< Storage engine */
+	struct kr_cdb_stats stats;
+	uint32_t ttl_min, ttl_max; /**< TTL limits */
+
+	/* A pair of stamps for detection of real-time shifts during runtime. */
+	struct timeval checkpoint_walltime; /**< Wall time on the last check-point. */
+	uint64_t checkpoint_monotime; /**< Monotonic milliseconds on the last check-point. */
+
+	uv_timer_t *health_timer; /**< Timer used for kr_cache_check_health() */
+};
+
+/**
+ * Open/create cache with provided storage options.
+ * @param cache cache structure to be initialized
+ * @param api   storage engine API
+ * @param opts  storage-specific options (may be NULL for default)
+ * @param mm    memory context.
+ * @return 0 or an error code
+ */
+KR_EXPORT
+int kr_cache_open(struct kr_cache *cache, const struct kr_cdb_api *api, struct kr_cdb_opts *opts, knot_mm_t *mm);
+
+/**
+ * Path to cache file to remove on critical out-of-space error. (do NOT modify it)
+ */
+KR_EXPORT extern
+const char *kr_cache_emergency_file_to_remove;
+
+/**
+ * Close persistent cache.
+ * @note This doesn't clear the data, just closes the connection to the database.
+ * @param cache structure
+ */
+KR_EXPORT
+void kr_cache_close(struct kr_cache *cache);
+
+/** Run after a row of operations to release transaction/lock if needed. */
+KR_EXPORT
+int kr_cache_commit(struct kr_cache *cache);
+
+/**
+ * Return true if cache is open and enabled.
+ */
+static inline bool kr_cache_is_open(struct kr_cache *cache)
+{
+	return cache->db != NULL;
+}
+
+/** (Re)set the time pair to the current values. */
+static inline void kr_cache_make_checkpoint(struct kr_cache *cache)
+{
+	cache->checkpoint_monotime = kr_now();
+	gettimeofday(&cache->checkpoint_walltime, NULL);
+}
+
+/**
+ * Insert RRSet into cache, replacing any existing data.
+ * @param cache cache structure
+ * @param rr inserted RRSet
+ * @param rrsig RRSIG for inserted RRSet (optional)
+ * @param rank rank of the data
+ * @param timestamp current time
+ * @return 0 or an errcode
+ */
+KR_EXPORT
+int kr_cache_insert_rr(struct kr_cache *cache, const knot_rrset_t *rr, const knot_rrset_t *rrsig, uint8_t rank, uint32_t timestamp);
+
+/**
+ * Clear all items from the cache.
+ * @param cache cache structure
+ * @return if nonzero is returned, there's a big problem - you probably want to abort(),
+ * 	perhaps except for kr_error(EAGAIN) which probably indicates transient errors.
+ */
+KR_EXPORT
+int kr_cache_clear(struct kr_cache *cache);
+
+
+/* ** This interface is temporary. ** */
+
+struct kr_cache_p {
+	uint32_t time;	/**< The time of inception. */
+	uint32_t ttl;	/**< TTL at inception moment.  Assuming it fits into int32_t ATM. */
+	uint8_t  rank;	/**< See enum kr_rank */
+	struct {
+		/* internal: pointer to eh struct */
+		void *raw_data, *raw_bound;
+	};
+};
+KR_EXPORT
+int kr_cache_peek_exact(struct kr_cache *cache, const knot_dname_t *name, uint16_t type,
+			struct kr_cache_p *peek);
+/* Parameters (qry, name, type) are used for timestamp and stale-serving decisions. */
+KR_EXPORT
+int32_t kr_cache_ttl(const struct kr_cache_p *peek, const struct kr_query *qry,
+		     const knot_dname_t *name, uint16_t type);
+
+KR_EXPORT
+int kr_cache_materialize(knot_rdataset_t *dst, const struct kr_cache_p *ref,
+			 knot_mm_t *pool);
+
+
+/**
+ * Remove an entry from cache.
+ * @param cache cache structure
+ * @param name dname
+ * @param type rr type
+ * @return number of deleted records, or negative error code
+ * @note only "exact hits" are considered ATM, and
+ * 	some other information may be removed alongside.
+ */
+KR_EXPORT
+int kr_cache_remove(struct kr_cache *cache, const knot_dname_t *name, uint16_t type);
+
+/**
+ * Get keys matching a dname lf prefix
+ * @param cache cache structure
+ * @param name dname
+ * @param exact_name whether to only consider exact name matches
+ * @param keyval matched key-value pairs
+ * @param maxcount limit on the number of returned key-value pairs
+ * @return result count or an errcode
+ * @note the cache keys are matched by prefix, i.e. it very much depends
+ * 	on their structure; CACHE_KEY_DEF.
+ */
+KR_EXPORT
+int kr_cache_match(struct kr_cache *cache, const knot_dname_t *name,
+		   bool exact_name, knot_db_val_t keyval[][2], int maxcount);
+
+/**
+ * Remove a subtree in cache.  It's like _match but removing them instead of returning.
+ * @return number of deleted entries or an errcode
+ */
+KR_EXPORT
+int kr_cache_remove_subtree(struct kr_cache *cache, const knot_dname_t *name,
+			    bool exact_name, int maxcount);
+
+/**
+ * Find the closest cached zone apex for a name (in cache).
+ * @param is_DS start searching one name higher
+ * @return the number of labels to remove from the name, or negative error code
+ * @note timestamp is found by a syscall, and stale-serving is not considered
+ */
+KR_EXPORT
+int kr_cache_closest_apex(struct kr_cache *cache, const knot_dname_t *name, bool is_DS,
+			  knot_dname_t **apex);
+
+/**
+ * Unpack dname and type from db key
+ * @param key db key representation
+ * @param buf output buffer of domain name in dname format
+ * @param type output for type
+ * @return length of dname or an errcode
+ * @note only "exact hits" are considered ATM, moreover xNAME records
+ * 	are "hidden" as NS. (see comments in struct entry_h)
+ */
+KR_EXPORT
+int kr_unpack_cache_key(knot_db_val_t key, knot_dname_t *buf, uint16_t *type);
+
+/** Periodic kr_cdb_api::check_health().
+ * @param interval in milliseconds.  0 for one-time check, -1 to stop the checks.
+ * @return see check_health() for one-time check; otherwise normal kr_error() code. */
+KR_EXPORT
+int kr_cache_check_health(struct kr_cache *cache, int interval);
+
diff --git a/lib/cache/cdb_api.h b/lib/cache/cdb_api.h
new file mode 100644
index 0000000..d94ea5e
--- /dev/null
+++ b/lib/cache/cdb_api.h
@@ -0,0 +1,97 @@
+/*  Copyright (C) 2016-2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+*/
+
+#pragma once
+
+#include <stdint.h>
+
+#include <libknot/db/db.h>
+
+/* Cache options. */
+struct kr_cdb_opts {
+	const char *path; /*!< Cache URI path. */
+	size_t maxsize;   /*!< Suggested cache size in bytes; pass 0 to keep unchanged/default. */
+};
+
+struct kr_cdb_stats {
+	uint64_t open;
+	uint64_t close;
+	uint64_t count;
+	uint64_t count_entries;
+	uint64_t clear;
+	uint64_t commit;
+	uint64_t read;
+	uint64_t read_miss;
+	uint64_t write;
+	uint64_t remove;
+	uint64_t remove_miss;
+	uint64_t match;
+	uint64_t match_miss;
+	uint64_t read_leq;
+	uint64_t read_leq_miss;
+	double usage_percent;
+};
+
+/*! Pointer to a cache structure.
+ *
+ * This struct is opaque and never defined; the purpose is to get better
+ * type safety than with void *.
+ */
+typedef struct kr_cdb *kr_cdb_pt;
+
+/*! Cache database API.
+  * This is a simplified version of generic DB API from libknot,
+  * that is tailored to caching purposes.
+  */
+struct kr_cdb_api {
+	const char *name;
+
+	/* Context operations */
+
+	int (*open)(kr_cdb_pt *db, struct kr_cdb_stats *stat, struct kr_cdb_opts *opts, knot_mm_t *mm);
+	void (*close)(kr_cdb_pt db, struct kr_cdb_stats *stat);
+	int (*count)(kr_cdb_pt db, struct kr_cdb_stats *stat);
+	int (*clear)(kr_cdb_pt db, struct kr_cdb_stats *stat);
+
+	/** Run after a row of operations to release transaction/lock if needed. */
+	int (*commit)(kr_cdb_pt db, struct kr_cdb_stats *stat);
+
+	/* Data access */
+
+	int (*read)(kr_cdb_pt db, struct kr_cdb_stats *stat,
+			const knot_db_val_t *key, knot_db_val_t *val, int maxcount);
+	int (*write)(kr_cdb_pt db, struct kr_cdb_stats *stat, const knot_db_val_t *key,
+			knot_db_val_t *val, int maxcount);
+
+	/** Remove maxcount keys.
+	 * \returns the number of succesfully removed keys or the first error code
+	 * It returns on first error, but ENOENT is not considered an error. */
+	int (*remove)(kr_cdb_pt db, struct kr_cdb_stats *stat,
+			knot_db_val_t keys[], int maxcount);
+
+	/* Specialised operations */
+
+	/** Find key-value pairs that are prefixed by the given key, limited by maxcount.
+	 * \return the number of pairs or negative error. */
+	int (*match)(kr_cdb_pt db, struct kr_cdb_stats *stat,
+			knot_db_val_t *key, knot_db_val_t keyval[][2], int maxcount);
+
+	/** Less-or-equal search (lexicographic ordering).
+	 * On successful return, key->data and val->data point to DB-owned data.
+	 * return: 0 for equality, > 0 for less, < 0 kr_error */
+	int (*read_leq)(kr_cdb_pt db, struct kr_cdb_stats *stat,
+			knot_db_val_t *key, knot_db_val_t *val);
+
+	/** Return estimated space usage (0--100). */
+	double (*usage_percent)(kr_cdb_pt db);
+
+	/** Return the current cache size limit in bytes; could be cached by check_health(). */
+	size_t (*get_maxsize)(kr_cdb_pt db);
+
+	/** Perform maintenance.
+	 * In LMDB case it checks whether data.mdb is still the same
+	 * and reopens it if it isn't; it errors out if the file doesn't exist anymore.
+	 * \return 0 if OK, 1 if reopened OK, < 0 kr_error */
+	int (*check_health)(kr_cdb_pt db, struct kr_cdb_stats *stat);
+};
diff --git a/lib/cache/cdb_lmdb.c b/lib/cache/cdb_lmdb.c
new file mode 100644
index 0000000..5f4db06
--- /dev/null
+++ b/lib/cache/cdb_lmdb.c
@@ -0,0 +1,854 @@
+/*  Copyright (C) 2016-2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+*/
+
+#include <assert.h>
+#include <fcntl.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <lmdb.h>
+
+#include "contrib/cleanup.h"
+#include "contrib/ucw/lib.h"
+#include "lib/cache/cdb_lmdb.h"
+#include "lib/cache/cdb_api.h"
+#include "lib/cache/api.h"
+#include "lib/cache/impl.h"
+#include "lib/utils.h"
+
+
+/* Defines */
+#define LMDB_DIR_MODE   0770
+#define LMDB_FILE_MODE  0660
+
+/* TODO: we rely on mirrors of these two structs not changing layout
+ * in libknot and knot resolver! */
+struct lmdb_env
+{
+	size_t mapsize;
+	MDB_dbi dbi;
+	MDB_env *env;
+
+	/** Cached transactions
+	 *
+	 * - only one of (ro,rw) may be active at once
+	 * - non-NULL .ro may be active or reset
+	 * - non-NULL .rw is always active
+	 */
+	struct {
+		bool ro_active, ro_curs_active;
+		MDB_txn *ro, *rw;
+		MDB_cursor *ro_curs;
+	} txn;
+
+	/* Cached part of struct stat for data.mdb. */
+	dev_t st_dev;
+	ino_t st_ino;
+	off_t st_size;
+	const char *mdb_data_path; /**< path to data.mdb, for convenience */
+};
+
+struct libknot_lmdb_env {
+	bool shared;
+	unsigned dbi;
+	void *env;
+	knot_mm_t *pool;
+};
+
+/** Type-safe conversion helper.
+ *
+ * We keep lmdb_env as a separate type from kr_db_pt, as different implementation of API
+ * would need to define the contents differently.
+ */
+static inline struct lmdb_env * db2env(kr_cdb_pt db)
+{
+	return (struct lmdb_env *)db;
+}
+static inline kr_cdb_pt env2db(struct lmdb_env *env)
+{
+	return (kr_cdb_pt)env;
+}
+
+static int cdb_commit(kr_cdb_pt db, struct kr_cdb_stats *stats);
+
+/** @brief Convert LMDB error code. */
+static int lmdb_error(int error)
+{
+	switch (error) {
+	case MDB_SUCCESS:
+		return kr_ok();
+	case MDB_NOTFOUND:
+		return kr_error(ENOENT);
+	case ENOSPC:
+	case MDB_MAP_FULL:
+	case MDB_TXN_FULL:
+		return kr_error(ENOSPC);
+	default:
+		kr_log_error("[cache] LMDB error: %s\n", mdb_strerror(error));
+		return kr_error(error);
+	}
+}
+
+/** Conversion between knot and lmdb structs for values. */
+static inline knot_db_val_t val_mdb2knot(MDB_val v)
+{
+	return (knot_db_val_t){ .len = v.mv_size, .data = v.mv_data };
+}
+static inline MDB_val val_knot2mdb(knot_db_val_t v)
+{
+	return (MDB_val){ .mv_size = v.len, .mv_data = v.data };
+}
+
+/** Refresh mapsize value from file, including env->mapsize.
+ * It's much lighter than reopen_env(). */
+static int refresh_mapsize(struct lmdb_env *env)
+{
+	int ret = cdb_commit(env2db(env), NULL);
+	if (!ret) ret = lmdb_error(mdb_env_set_mapsize(env->env, 0));
+	if (ret) return ret;
+
+	MDB_envinfo info;
+	ret = lmdb_error(mdb_env_info(env->env, &info));
+	if (ret) return ret;
+
+	env->mapsize = info.me_mapsize;
+	if (env->mapsize != env->st_size) {
+		kr_log_info("[cache] suspicious size of cache file '%s'"
+				": file size %zu != LMDB map size %zu\n",
+				env->mdb_data_path, (size_t)env->st_size, env->mapsize);
+	}
+	return kr_ok();
+}
+
+#define FLAG_RENEW (2*MDB_RDONLY)
+/** mdb_txn_begin or _renew + handle retries in some situations
+ *
+ * The retrying logic is so ugly that it has its own function.
+ * \note this assumes no transactions are active
+ * \return MDB_ errcode, not usual kr_error(...)
+ */
+static int txn_get_noresize(struct lmdb_env *env, unsigned int flag, MDB_txn **txn)
+{
+	assert(!env->txn.rw && (!env->txn.ro || !env->txn.ro_active));
+	int attempts = 0;
+	int ret;
+retry:
+	/* Do a few attempts in case we encounter multiple issues at once. */
+	if (++attempts > 2) {
+		return kr_error(1);
+	}
+
+	if (flag == FLAG_RENEW) {
+		ret = mdb_txn_renew(*txn);
+	} else {
+		ret = mdb_txn_begin(env->env, NULL, flag, txn);
+	}
+
+	if (unlikely(ret == MDB_MAP_RESIZED)) {
+		kr_log_info("[cache] detected size increased by another process\n");
+		ret = refresh_mapsize(env);
+		if (ret == 0)
+			goto retry;
+	} else if (unlikely(ret == MDB_READERS_FULL)) {
+		int cleared;
+		ret = mdb_reader_check(env->env, &cleared);
+		if (ret == MDB_SUCCESS)
+			kr_log_info("[cache] cleared %d stale reader locks\n", cleared);
+		else
+			kr_log_error("[cache] failed to clear stale reader locks: "
+					"LMDB error %d %s\n", ret, mdb_strerror(ret));
+		goto retry;
+	}
+	return ret;
+}
+
+/** Obtain a transaction.  (they're cached in env->txn) */
+static int txn_get(struct lmdb_env *env, MDB_txn **txn, bool rdonly)
+{
+	assert(env && txn);
+	if (env->txn.rw) {
+		/* Reuse the *open* RW txn even if only reading is requested.
+		 * We leave the management of this to the cdb_commit command.
+		 * The user may e.g. want to do some reads between the writes. */
+		*txn = env->txn.rw;
+		return kr_ok();
+	}
+
+	if (!rdonly) {
+		/* avoid two active transactions */
+		if (env->txn.ro && env->txn.ro_active) {
+			mdb_txn_reset(env->txn.ro);
+			env->txn.ro_active = false;
+			env->txn.ro_curs_active = false;
+		}
+		int ret = txn_get_noresize(env, 0/*RW*/, &env->txn.rw);
+		if (ret == MDB_SUCCESS) {
+			*txn = env->txn.rw;
+			assert(*txn);
+		}
+		return lmdb_error(ret);
+	}
+
+	/* Get an active RO txn and return it. */
+	int ret = MDB_SUCCESS;
+	if (!env->txn.ro) { //:unlikely
+		ret = txn_get_noresize(env, MDB_RDONLY, &env->txn.ro);
+	} else if (!env->txn.ro_active) {
+		ret = txn_get_noresize(env, FLAG_RENEW, &env->txn.ro);
+	}
+	if (ret != MDB_SUCCESS) {
+		return lmdb_error(ret);
+	}
+	env->txn.ro_active = true;
+	*txn = env->txn.ro;
+	assert(*txn);
+	return kr_ok();
+}
+
+static int cdb_commit(kr_cdb_pt db, struct kr_cdb_stats *stats)
+{
+	struct lmdb_env *env = db2env(db);
+	int ret = kr_ok();
+	if (env->txn.rw) {
+		if (stats) stats->commit++;
+		ret = lmdb_error(mdb_txn_commit(env->txn.rw));
+		env->txn.rw = NULL; /* the transaction got freed even in case of errors */
+	} else if (env->txn.ro && env->txn.ro_active) {
+		mdb_txn_reset(env->txn.ro);
+		env->txn.ro_active = false;
+		env->txn.ro_curs_active = false;
+	}
+	return ret;
+}
+
+/** Obtain a read-only cursor (and a read-only transaction). */
+static int txn_curs_get(struct lmdb_env *env, MDB_cursor **curs, struct kr_cdb_stats *stats)
+{
+	assert(env && curs);
+	if (env->txn.ro_curs_active) {
+		goto success;
+	}
+	/* Only in a read-only txn; TODO: it's a bit messy/coupled */
+	if (env->txn.rw) {
+		int ret = cdb_commit(env2db(env), stats);
+		if (ret) return ret;
+	}
+	MDB_txn *txn = NULL;
+	int ret = txn_get(env, &txn, true);
+	if (ret) return ret;
+
+	if (env->txn.ro_curs) {
+		ret = mdb_cursor_renew(txn, env->txn.ro_curs);
+	} else {
+		ret = mdb_cursor_open(txn, env->dbi, &env->txn.ro_curs);
+	}
+	if (ret) return lmdb_error(ret);
+	env->txn.ro_curs_active = true;
+success:
+	assert(env->txn.ro_curs_active && env->txn.ro && env->txn.ro_active
+		&& !env->txn.rw);
+	*curs = env->txn.ro_curs;
+	assert(*curs);
+	return kr_ok();
+}
+
+static void txn_free_ro(struct lmdb_env *env)
+{
+	if (env->txn.ro_curs) {
+		mdb_cursor_close(env->txn.ro_curs);
+		env->txn.ro_curs = NULL;
+	}
+	if (env->txn.ro) {
+		mdb_txn_abort(env->txn.ro);
+		env->txn.ro = NULL;
+	}
+}
+
+/** Abort all transactions.
+ *
+ * This is useful after an error happens, as those (always?) require abortion.
+ * It's possible that _reset() would suffice and marking cursor inactive,
+ * but these errors should be rare so let's close them completely. */
+static void txn_abort(struct lmdb_env *env)
+{
+	txn_free_ro(env);
+	if (env->txn.rw) {
+		mdb_txn_abort(env->txn.rw);
+		env->txn.rw = NULL; /* the transaction got freed even in case of errors */
+	}
+}
+
+/*! \brief Close the database. */
+static void cdb_close_env(struct lmdb_env *env, struct kr_cdb_stats *stats)
+{
+	assert(env && env->env);
+
+	/* Get rid of any transactions. */
+	txn_free_ro(env);
+	cdb_commit(env2db(env), stats);
+
+	mdb_env_sync(env->env, 1);
+	stats->close++;
+	mdb_dbi_close(env->env, env->dbi);
+	mdb_env_close(env->env);
+	free_const(env->mdb_data_path);
+	memset(env, 0, sizeof(*env));
+}
+
+/** We assume that *env is zeroed and we return it zeroed on errors. */
+static int cdb_open_env(struct lmdb_env *env, const char *path, const size_t mapsize,
+		struct kr_cdb_stats *stats)
+{
+	int ret = mkdir(path, LMDB_DIR_MODE);
+	if (ret && errno != EEXIST) return kr_error(errno);
+
+	stats->open++;
+	ret = mdb_env_create(&env->env);
+	if (ret != MDB_SUCCESS) return lmdb_error(ret);
+
+	env->mdb_data_path = kr_absolutize_path(path, "data.mdb");
+	if (!env->mdb_data_path) {
+		ret = ENOMEM;
+		goto error_sys;
+	}
+
+	/* Set map size, rounded to page size. */
+	errno = 0;
+	const long pagesize = sysconf(_SC_PAGESIZE);
+	if (errno) {
+		ret = errno;
+		goto error_sys;
+	}
+
+	const bool size_requested = mapsize;
+	if (size_requested) {
+		env->mapsize = (mapsize / pagesize) * pagesize;
+		ret = mdb_env_set_mapsize(env->env, env->mapsize);
+		if (ret != MDB_SUCCESS) goto error_mdb;
+	}
+
+	/* Cache doesn't require durability, we can be
+	 * loose with the requirements as a tradeoff for speed. */
+	const unsigned flags = MDB_WRITEMAP | MDB_MAPASYNC | MDB_NOTLS;
+	ret = mdb_env_open(env->env, path, flags, LMDB_FILE_MODE);
+	if (ret != MDB_SUCCESS) goto error_mdb;
+
+	mdb_filehandle_t fd = -1;
+	ret = mdb_env_get_fd(env->env, &fd);
+	if (ret != MDB_SUCCESS) goto error_mdb;
+
+	struct stat st;
+	if (fstat(fd, &st)) {
+		ret = errno;
+		goto error_sys;
+	}
+	env->st_dev = st.st_dev;
+	env->st_ino = st.st_ino;
+	env->st_size = st.st_size;
+
+	/* Get the real mapsize.  Shrinking can be restricted, etc.
+	 * Unfortunately this is only reliable when not setting the size explicitly. */
+	if (!size_requested) {
+		ret = refresh_mapsize(env);
+		if (ret) goto error_sys;
+	}
+
+	/* Open the database. */
+	MDB_txn *txn = NULL;
+	ret = mdb_txn_begin(env->env, NULL, 0, &txn);
+	if (ret != MDB_SUCCESS) goto error_mdb;
+
+	ret = mdb_dbi_open(txn, NULL, 0, &env->dbi);
+	if (ret != MDB_SUCCESS) {
+		mdb_txn_abort(txn);
+		goto error_mdb;
+	}
+
+#if !defined(__MACOSX__) && !(defined(__APPLE__) && defined(__MACH__))
+	if (size_requested) {
+		ret = posix_fallocate(fd, 0, MAX(env->mapsize, env->st_size));
+	} else {
+		ret = 0;
+	}
+	if (ret == EINVAL) {
+		/* POSIX says this can happen when the feature isn't supported by the FS.
+		 * We haven't seen this happen on Linux+glibc but it was reported on FreeBSD.*/
+		kr_log_info("[cache] space pre-allocation failed and ignored; "
+				"your (file)system probably doesn't support it.\n");
+	} else if (ret != 0) {
+		mdb_txn_abort(txn);
+		goto error_sys;
+	}
+#endif
+
+	stats->commit++;
+	ret = mdb_txn_commit(txn);
+	if (ret != MDB_SUCCESS) goto error_mdb;
+
+	return kr_ok();
+
+error_mdb:
+	ret = lmdb_error(ret);
+error_sys:
+	free_const(env->mdb_data_path);
+	stats->close++;
+	mdb_env_close(env->env);
+	memset(env, 0, sizeof(*env));
+	return kr_error(ret);
+}
+
+static int cdb_init(kr_cdb_pt *db, struct kr_cdb_stats *stats,
+		struct kr_cdb_opts *opts, knot_mm_t *pool)
+{
+	if (!db || !stats || !opts) {
+		return kr_error(EINVAL);
+	}
+
+	/* Open the database. */
+	struct lmdb_env *env = calloc(1, sizeof(*env));
+	if (!env) {
+		return kr_error(ENOMEM);
+	}
+	int ret = cdb_open_env(env, opts->path, opts->maxsize, stats);
+	if (ret != 0) {
+		free(env);
+		return ret;
+	}
+
+	*db = env2db(env);
+	return 0;
+}
+
+static void cdb_deinit(kr_cdb_pt db, struct kr_cdb_stats *stats)
+{
+	cdb_close_env(db2env(db), stats);
+	free(db);
+}
+
+static int cdb_count(kr_cdb_pt db, struct kr_cdb_stats *stats)
+{
+	struct lmdb_env *env = db2env(db);
+	MDB_txn *txn = NULL;
+	int ret = txn_get(env, &txn, true);
+	if (ret != 0) {
+		return ret;
+	}
+
+	MDB_stat stat;
+	stats->count++;
+	ret = mdb_stat(txn, env->dbi, &stat);
+
+	if (ret == MDB_SUCCESS) {
+		return stat.ms_entries;
+	} else {
+		txn_abort(env);
+		return lmdb_error(ret);
+	}
+}
+
+static int reopen_env(struct lmdb_env *env, struct kr_cdb_stats *stats, const size_t mapsize)
+{
+	/* Keep copy as it points to current handle internals. */
+	const char *path;
+	int ret = mdb_env_get_path(env->env, &path);
+	if (ret != MDB_SUCCESS) {
+		return lmdb_error(ret);
+	}
+	auto_free char *path_copy = strdup(path);
+	cdb_close_env(env, stats);
+	return cdb_open_env(env, path_copy, mapsize, stats);
+}
+
+static int cdb_check_health(kr_cdb_pt db, struct kr_cdb_stats *stats)
+{
+	struct lmdb_env *env = db2env(db);
+
+	struct stat st;
+	if (stat(env->mdb_data_path, &st)) {
+		int ret = errno;
+		return kr_error(ret);
+	}
+
+	if (st.st_dev != env->st_dev || st.st_ino != env->st_ino) {
+		kr_log_verbose("[cache] cache file has been replaced, reopening\n");
+		int ret = reopen_env(env, stats, 0); // we accept mapsize from the new file
+		return ret == 0 ? 1 : ret;
+	}
+
+	/* Cache check through file size works OK without reopening,
+	 * contrary to methods based on mdb_env_info(). */
+	if (st.st_size == env->st_size)
+		return kr_ok();
+	kr_log_info("[cache] detected size change (by another instance?) of file '%s'"
+			": file size %zu -> file size %zu\n",
+			env->mdb_data_path, (size_t)env->st_size, (size_t)st.st_size);
+	env->st_size = st.st_size; // avoid retrying in cycle even if we fail
+	return refresh_mapsize(env);
+}
+
+/** Obtain exclusive (advisory) lock by creating a file, returning FD or negative kr_error().
+ * The lock is auto-released by OS in case the process finishes in any way (file remains). */
+static int lockfile_get(const char *path)
+{
+	assert(path);
+	const int fd = open(path, O_CREAT|O_RDWR, S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP);
+	if (fd < 0)
+		return kr_error(errno);
+
+	struct flock lock_info;
+	memset(&lock_info, 0, sizeof(lock_info));
+	lock_info.l_type = F_WRLCK;
+	lock_info.l_whence = SEEK_SET;
+	lock_info.l_start = 0;
+	lock_info.l_len = 1; // it's OK for locks to extend beyond the end of the file
+	int err;
+	do {
+		err = fcntl(fd, F_SETLK, &lock_info);
+	} while (err == -1 && errno == EINTR);
+	if (err) {
+		close(fd);
+		return kr_error(errno);
+	}
+	return fd;
+}
+
+/** Release and remove lockfile created by lockfile_get().  Return kr_error(). */
+static int lockfile_release(int fd)
+{
+	assert(fd > 0); // fd == 0 is surely a mistake, in our case at least
+	if (close(fd)) {
+		return kr_error(errno);
+	} else {
+		return kr_ok();
+	}
+}
+
+static int cdb_clear(kr_cdb_pt db, struct kr_cdb_stats *stats)
+{
+	struct lmdb_env *env = db2env(db);
+	stats->clear++;
+	/* First try mdb_drop() to clear the DB; this may fail with ENOSPC. */
+	{
+		MDB_txn *txn = NULL;
+		int ret = txn_get(env, &txn, false);
+		if (ret == kr_ok()) {
+			ret = lmdb_error(mdb_drop(txn, env->dbi, 0));
+			if (ret == kr_ok()) {
+				ret = cdb_commit(db, stats);
+			}
+			if (ret == kr_ok()) {
+				return ret;
+			}
+		}
+		kr_log_info("[cache] clearing error, falling back\n");
+	}
+	/* Fallback: we'll remove the database files and reopen.
+	 * Other instances can continue to use the removed lmdb,
+	 * though it's best for them to reopen soon. */
+
+	/* We are about to switch to a different file, so end all txns, to be sure. */
+	txn_free_ro(env);
+	(void) cdb_commit(db, stats);
+
+	const char *path = NULL;
+	int ret = mdb_env_get_path(env->env, &path);
+	if (ret != MDB_SUCCESS) {
+		return lmdb_error(ret);
+	}
+	auto_free char *mdb_lockfile = kr_strcatdup(2, path, "/lock.mdb");
+	auto_free char *lockfile = kr_strcatdup(2, path, "/krcachelock");
+	if (!mdb_lockfile || !lockfile) {
+		return kr_error(ENOMEM);
+	}
+
+	/* Find if we get a lock on lockfile. */
+	const int lockfile_fd = lockfile_get(lockfile);
+	if (lockfile_fd < 0) {
+		kr_log_error("[cache] clearing failed to get ./krcachelock (%s); retry later\n",
+				kr_strerror(lockfile_fd));
+		/* As we're out of space (almost certainly - mdb_drop didn't work),
+		 * we will retry on the next failing write operation. */
+		return kr_error(EAGAIN);
+	}
+
+	/* We acquired lockfile.  Now find whether *.mdb are what we have open now.
+	 * If they are not we don't want to remove them; most likely they have been
+	 * cleaned by another instance. */
+	ret = cdb_check_health(db, stats);
+	if (ret != 0) {
+		if (ret == 1) // file changed and reopened successfuly
+			ret = kr_ok();
+		// else pass some other error
+	} else {
+		kr_log_verbose("[cache] clear: identical files, unlinking\n");
+		// coverity[toctou]
+		unlink(env->mdb_data_path);
+		unlink(mdb_lockfile);
+		ret = reopen_env(env, stats, env->mapsize);
+	}
+
+	/* Environment updated, release lockfile. */
+	int lrerr = lockfile_release(lockfile_fd);
+	if (lrerr) {
+		kr_log_error("[cache] failed to release ./krcachelock: %s\n",
+				kr_strerror(lrerr));
+	}
+	return ret;
+}
+
+static int cdb_readv(kr_cdb_pt db, struct kr_cdb_stats *stats,
+		const knot_db_val_t *key, knot_db_val_t *val, int maxcount)
+{
+	struct lmdb_env *env = db2env(db);
+	MDB_txn *txn = NULL;
+	int ret = txn_get(env, &txn, true);
+	if (ret) {
+		return ret;
+	}
+
+	for (int i = 0; i < maxcount; ++i) {
+		/* Convert key structs */
+		MDB_val _key = val_knot2mdb(key[i]);
+		MDB_val _val = val_knot2mdb(val[i]);
+		stats->read++;
+		ret = mdb_get(txn, env->dbi, &_key, &_val);
+		if (ret != MDB_SUCCESS) {
+			if (ret == MDB_NOTFOUND) {
+				stats->read_miss++;
+			} else {
+				txn_abort(env);
+			}
+			ret = lmdb_error(ret);
+			if (ret == kr_error(ENOSPC)) {
+				/* we're likely to be forced to cache clear anyway */
+				ret = kr_error(ENOENT);
+			}
+			return ret;
+		}
+		/* Update the result. */
+		val[i] = val_mdb2knot(_val);
+	}
+	return kr_ok();
+}
+
+static int cdb_write(struct lmdb_env *env, MDB_txn **txn, const knot_db_val_t *key,
+			knot_db_val_t *val, unsigned flags,
+			struct kr_cdb_stats *stats)
+{
+	/* Convert key structs and write */
+	MDB_val _key = val_knot2mdb(*key);
+	MDB_val _val = val_knot2mdb(*val);
+	stats->write++;
+	int ret = mdb_put(*txn, env->dbi, &_key, &_val, flags);
+
+	/* We don't try to recover from MDB_TXN_FULL. */
+	if (ret != MDB_SUCCESS) {
+		txn_abort(env);
+		return lmdb_error(ret);
+	}
+
+	/* Update the result. */
+	val->data = _val.mv_data;
+	val->len = _val.mv_size;
+	return kr_ok();
+}
+
+static int cdb_writev(kr_cdb_pt db, struct kr_cdb_stats *stats,
+		const knot_db_val_t *key, knot_db_val_t *val, int maxcount)
+{
+	struct lmdb_env *env = db2env(db);
+	MDB_txn *txn = NULL;
+	int ret = txn_get(env, &txn, false);
+
+	for (int i = 0; ret == kr_ok() && i < maxcount; ++i) {
+		/* This is LMDB specific optimisation,
+		 * if caller specifies value with NULL data and non-zero length,
+		 * LMDB will preallocate the entry for caller and leave write
+		 * transaction open, caller is responsible for syncing thus committing transaction.
+		 */
+		unsigned mdb_flags = 0;
+		if (val[i].len > 0 && val[i].data == NULL) {
+			mdb_flags |= MDB_RESERVE;
+		}
+		ret = cdb_write(env, &txn, &key[i], &val[i], mdb_flags, stats);
+	}
+
+	return ret;
+}
+
+static int cdb_remove(kr_cdb_pt db, struct kr_cdb_stats *stats,
+		knot_db_val_t keys[], int maxcount)
+{
+	struct lmdb_env *env = db2env(db);
+	MDB_txn *txn = NULL;
+	int ret = txn_get(env, &txn, false);
+	int deleted = 0;
+
+	for (int i = 0; ret == kr_ok() && i < maxcount; ++i) {
+		MDB_val _key = val_knot2mdb(keys[i]);
+		MDB_val val = { 0, NULL };
+		stats->remove++;
+		ret = lmdb_error(mdb_del(txn, env->dbi, &_key, &val));
+		if (ret == kr_ok())
+			deleted++;
+		else if (ret == KNOT_ENOENT) {
+			stats->remove_miss++;
+			ret = kr_ok();  /* skip over non-existing entries */
+		} else {
+			txn_abort(env);
+			break;
+		}
+	}
+
+	return ret < 0 ? ret : deleted;
+}
+
+static int cdb_match(kr_cdb_pt db, struct kr_cdb_stats *stats,
+		knot_db_val_t *key, knot_db_val_t keyval[][2], int maxcount)
+{
+	struct lmdb_env *env = db2env(db);
+	MDB_txn *txn = NULL;
+	int ret = txn_get(env, &txn, true);
+	if (ret != 0) {
+		return ret;
+	}
+
+	/* LATER(optim.): use txn_curs_get() instead, to save resources. */
+	MDB_cursor *cur = NULL;
+	ret = mdb_cursor_open(txn, env->dbi, &cur);
+	if (ret != 0) {
+		txn_abort(env);
+		return lmdb_error(ret);
+	}
+
+	MDB_val cur_key = val_knot2mdb(*key);
+	MDB_val cur_val = { 0, NULL };
+	stats->match++;
+	ret = mdb_cursor_get(cur, &cur_key, &cur_val, MDB_SET_RANGE);
+	if (ret != MDB_SUCCESS) {
+		mdb_cursor_close(cur);
+		if (ret != MDB_NOTFOUND) {
+			txn_abort(env);
+		}
+		return lmdb_error(ret);
+	}
+
+	int results = 0;
+	while (ret == MDB_SUCCESS) {
+		/* Retrieve current key and compare with prefix */
+		if (cur_key.mv_size < key->len || memcmp(cur_key.mv_data, key->data, key->len) != 0) {
+			break;
+		}
+		/* Add to result set */
+		if (results < maxcount) {
+			keyval[results][0] = val_mdb2knot(cur_key);
+			keyval[results][1] = val_mdb2knot(cur_val);
+			++results;
+		} else {
+			break;
+		}
+		stats->match++;
+		ret = mdb_cursor_get(cur, &cur_key, &cur_val, MDB_NEXT);
+	}
+
+	mdb_cursor_close(cur);
+	if (ret != MDB_SUCCESS && ret != MDB_NOTFOUND) {
+		txn_abort(env);
+		return lmdb_error(ret);
+	} else if (results == 0) {
+		stats->match_miss++;
+	}
+	return results;
+}
+
+
+static int cdb_read_leq(kr_cdb_pt db, struct kr_cdb_stats *stats,
+		knot_db_val_t *key, knot_db_val_t *val)
+{
+	assert(db && key && key->data && val);
+	struct lmdb_env *env = db2env(db);
+	MDB_cursor *curs = NULL;
+	int ret = txn_curs_get(env, &curs, stats);
+	if (ret) return ret;
+
+	MDB_val key2_m = val_knot2mdb(*key);
+	MDB_val val2_m = { 0, NULL };
+	stats->read_leq++;
+	ret = mdb_cursor_get(curs, &key2_m, &val2_m, MDB_SET_RANGE);
+	if (ret) goto failure;
+	/* test for equality //:unlikely */
+	if (key2_m.mv_size == key->len
+	    && memcmp(key2_m.mv_data, key->data, key->len) == 0) {
+		ret = 0; /* equality */
+		goto success;
+	}
+	stats->read_leq_miss++;
+
+	/* we must be greater than key; do one step to smaller */
+	stats->read_leq++;
+	ret = mdb_cursor_get(curs, &key2_m, &val2_m, MDB_PREV);
+	if (ret) goto failure;
+	ret = 1;
+success:
+	/* finalize the output */
+	*key = val_mdb2knot(key2_m);
+	*val = val_mdb2knot(val2_m);
+	return ret;
+failure:
+	if (ret == MDB_NOTFOUND) {
+		stats->read_leq_miss++;
+	} else {
+		txn_abort(env);
+	}
+	return lmdb_error(ret);
+}
+
+static double cdb_usage_percent(kr_cdb_pt db)
+{
+	knot_db_t *kdb = kr_cdb_pt2knot_db_t(db);
+	const size_t db_size = knot_db_lmdb_get_mapsize(kdb);
+	const size_t db_usage_abs = knot_db_lmdb_get_usage(kdb);
+	const double db_usage = (double)db_usage_abs / db_size * 100.0;
+	free(kdb);
+	return db_usage;
+}
+
+static size_t cdb_get_maxsize(kr_cdb_pt db)
+{
+	return db2env(db)->mapsize;
+}
+
+/** Conversion between knot and lmdb structs. */
+knot_db_t *kr_cdb_pt2knot_db_t(kr_cdb_pt db)
+{
+	/* this is struct lmdb_env as in resolver/cdb_lmdb.c */
+	const struct lmdb_env *kres_db = db2env(db);
+	struct libknot_lmdb_env *libknot_db = malloc(sizeof(*libknot_db));
+	if (libknot_db != NULL) {
+		libknot_db->shared = false;
+		libknot_db->pool = NULL;
+		libknot_db->env = kres_db->env;
+		libknot_db->dbi = kres_db->dbi;
+	}
+	return libknot_db;
+}
+
+const struct kr_cdb_api *kr_cdb_lmdb(void)
+{
+	static const struct kr_cdb_api api = {
+		"lmdb",
+		cdb_init, cdb_deinit, cdb_count, cdb_clear, cdb_commit,
+		cdb_readv, cdb_writev, cdb_remove,
+		cdb_match,
+		cdb_read_leq,
+		cdb_usage_percent,
+		cdb_get_maxsize,
+		cdb_check_health,
+	};
+
+	return &api;
+}
diff --git a/lib/cache/cdb_lmdb.h b/lib/cache/cdb_lmdb.h
new file mode 100644
index 0000000..3429a22
--- /dev/null
+++ b/lib/cache/cdb_lmdb.h
@@ -0,0 +1,16 @@
+/*  Copyright (C) 2016-2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+*/
+
+#pragma once
+
+#include "lib/cache/cdb_api.h"
+#include "lib/defines.h"
+
+KR_EXPORT KR_CONST
+const struct kr_cdb_api *kr_cdb_lmdb(void);
+
+/** Create a pointer for knot_db_lmdb_api.  You free() it to release it. */
+KR_EXPORT
+knot_db_t *kr_cdb_pt2knot_db_t(kr_cdb_pt db);
+
diff --git a/lib/cache/entry_list.c b/lib/cache/entry_list.c
new file mode 100644
index 0000000..f2d9d05
--- /dev/null
+++ b/lib/cache/entry_list.c
@@ -0,0 +1,284 @@
+/*  Copyright (C) 2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+/** @file
+ * Implementation of chaining in struct entry_h.  Prototypes in ./impl.h
+ */
+
+#include "lib/cache/impl.h"
+#include "lib/utils.h"
+
+
+static int entry_h_len(knot_db_val_t val);
+
+
+void entry_list_memcpy(struct entry_apex *ea, entry_list_t list)
+{
+	assert(ea);
+	memset(ea, 0, offsetof(struct entry_apex, data));
+	ea->has_ns	= list[EL_NS	].len;
+	ea->has_cname	= list[EL_CNAME	].len;
+	ea->has_dname	= list[EL_DNAME	].len;
+	for (int i = 0; i < ENTRY_APEX_NSECS_CNT; ++i) {
+		ea->nsecs[i] =   list[i].len == 0 ? 0 :
+				(list[i].len == 4 ? 1 : 3);
+	}
+	uint8_t *it = ea->data;
+	for (int i = 0; i < EL_LENGTH; ++i) {
+		if (list[i].data) {
+			memcpy(it, list[i].data, list[i].len);
+			/* LATER(optim.): coalesce consecutive writes? */
+		} else {
+			list[i].data = it;
+		}
+		it += to_even(list[i].len);
+	}
+}
+
+int entry_list_parse(const knot_db_val_t val, entry_list_t list)
+{
+	const bool ok = val.data && val.len && list;
+	if (!ok) {
+		assert(!EINVAL);
+		return kr_error(EINVAL);
+	}
+	/* Parse the apex itself (nsec parameters). */
+	const struct entry_apex *ea = entry_apex_consistent(val);
+	if (!ea) {
+		return kr_error(EILSEQ);
+	}
+	const uint8_t *it = ea->data,
+		*it_bound = knot_db_val_bound(val);
+	for (int i = 0; i < ENTRY_APEX_NSECS_CNT; ++i) {
+		if (it > it_bound) {
+			return kr_error(EILSEQ);
+		}
+		list[i].data = (void *)it;
+		switch (ea->nsecs[i]) {
+		case 0:
+			list[i].len = 0;
+			break;
+		case 1:
+			list[i].len = sizeof(uint32_t); /* just timestamp */
+			break;
+		case 3: { /* timestamp + NSEC3PARAM wire */
+			if (it + sizeof(uint32_t) + 4 > it_bound) {
+				return kr_error(EILSEQ);
+			}
+			list[i].len = sizeof(uint32_t)
+				+ nsec_p_rdlen(it + sizeof(uint32_t));
+			break;
+			}
+		default:
+			return kr_error(EILSEQ);
+		};
+		it += to_even(list[i].len);
+	}
+	/* Parse every entry_h. */
+	for (int i = ENTRY_APEX_NSECS_CNT; i < EL_LENGTH; ++i) {
+		list[i].data = (void *)it;
+		bool has_type;
+		switch (i) {
+		case EL_NS:	has_type = ea->has_ns;		break;
+		case EL_CNAME:	has_type = ea->has_cname;	break;
+		case EL_DNAME:	has_type = ea->has_dname;	break;
+		default: assert(false); return kr_error(EINVAL); /* something very bad */
+		}
+		if (!has_type) {
+			list[i].len = 0;
+			continue;
+		}
+		if (it >= it_bound) {
+			assert(!EILSEQ);
+			return kr_error(EILSEQ);
+		}
+		const int len = entry_h_len(
+			(knot_db_val_t){ .data = (void *)it, .len = it_bound - it });
+		if (len < 0) {
+			assert(false);
+			return kr_error(len);
+		}
+		list[i].len = len;
+		it += to_even(len);
+	}
+	assert(it == it_bound);
+	return kr_ok();
+}
+
+/** Given a valid entry header, find its length (i.e. offset of the next entry).
+ * \param val The beginning of the data and the bound (read only).
+ */
+static int entry_h_len(const knot_db_val_t val)
+{
+	const bool ok = val.data && ((ssize_t)val.len) > 0;
+	if (!ok) return kr_error(EINVAL);
+	const struct entry_h *eh = val.data;
+	const uint8_t *d = eh->data; /* iterates over the data in entry */
+	const uint8_t *data_bound = knot_db_val_bound(val);
+	if (d >= data_bound) return kr_error(EILSEQ);
+	if (!eh->is_packet) { /* Positive RRset + its RRsig set (may be empty). */
+		int sets = 2;
+		while (sets-- > 0) {
+			d += KR_CACHE_RR_COUNT_SIZE + rdataset_dematerialized_size(d, NULL);
+			if (d > data_bound) {
+				assert(!EILSEQ);
+				return kr_error(EILSEQ);
+			}
+		}
+	} else { /* A "packet" (opaque ATM). */
+		uint16_t len;
+		if (d + sizeof(len) > data_bound) return kr_error(EILSEQ);
+		memcpy(&len, d, sizeof(len));
+		d += 2 + to_even(len);
+	}
+	if (d > data_bound) {
+		assert(!EILSEQ);
+		return kr_error(EILSEQ);
+	}
+	return d - (uint8_t *)val.data;
+}
+
+struct entry_apex * entry_apex_consistent(knot_db_val_t val)
+{
+	//XXX: check lengths, etc.
+	return val.data;
+}
+
+/* See the header file. */
+int entry_h_seek(knot_db_val_t *val, uint16_t type)
+{
+	int i = -1;
+	switch (type) {
+	case KNOT_RRTYPE_NS:	i = EL_NS;	break;
+	case KNOT_RRTYPE_CNAME:	i = EL_CNAME;	break;
+	case KNOT_RRTYPE_DNAME:	i = EL_DNAME;	break;
+	default:		return kr_ok();
+	}
+
+	entry_list_t el;
+	int ret = entry_list_parse(*val, el);
+	if (ret) return ret;
+	*val = el[i];
+	return val->len ? kr_ok() : kr_error(ENOENT);
+}
+
+static int cache_write_or_clear(struct kr_cache *cache, const knot_db_val_t *key,
+				knot_db_val_t *val, const struct kr_query *qry)
+{
+	int ret = cache_op(cache, write, key, val, 1);
+	if (!ret) return kr_ok();
+
+	if (ret != kr_error(ENOSPC)) { /* failing a write isn't too bad */
+		VERBOSE_MSG(qry, "=> failed backend write, ret = %d\n", ret);
+		return kr_error(ret);
+	}
+
+	/* Cache is overfull.  Using kres-cache-gc service should prevent this.
+	 * As a fallback, try clearing it. */
+	ret = kr_cache_clear(cache);
+	switch (ret) {
+	default:
+		kr_log_error("CRITICAL: clearing cache failed: %s; fatal error, aborting\n",
+				kr_strerror(ret));
+		abort();
+	case 0:
+		kr_log_info("[cache] overfull cache cleared\n");
+	case -EAGAIN: // fall-through; krcachelock race -> retry later
+		return kr_error(ENOSPC);
+	}
+}
+
+
+/* See the header file. */
+int entry_h_splice(
+	knot_db_val_t *val_new_entry, uint8_t rank,
+	const knot_db_val_t key, const uint16_t ktype, const uint16_t type,
+	const knot_dname_t *owner/*log only*/,
+	const struct kr_query *qry, struct kr_cache *cache, uint32_t timestamp)
+{
+	//TODO: another review, perhaps incuding the API
+	const bool ok = val_new_entry && val_new_entry->len > 0;
+	if (!ok) {
+		assert(!EINVAL);
+		return kr_error(EINVAL);
+	}
+
+	int i_type;
+	switch (type) {
+	case KNOT_RRTYPE_NS:	i_type = EL_NS;		break;
+	case KNOT_RRTYPE_CNAME:	i_type = EL_CNAME;	break;
+	case KNOT_RRTYPE_DNAME:	i_type = EL_DNAME;	break;
+	default:		i_type = 0;
+	}
+
+	/* Get eh_orig (original entry), and also el list if multi-entry case. */
+	const struct entry_h *eh_orig = NULL;
+	entry_list_t el;
+	int ret = -1;
+	if (!kr_rank_test(rank, KR_RANK_SECURE) || ktype == KNOT_RRTYPE_NS) {
+		knot_db_val_t val;
+		ret = cache_op(cache, read, &key, &val, 1);
+		if (i_type) {
+			if (!ret) ret = entry_list_parse(val, el);
+			if (ret) memset(el, 0, sizeof(el));
+			val = el[i_type];
+		}
+		/* val is on the entry, in either case (or error) */
+		if (!ret) {
+			eh_orig = entry_h_consistent_E(val, type);
+		}
+	} else {
+		/* We want to fully overwrite the entry, so don't even read it. */
+		memset(el, 0, sizeof(el));
+	}
+
+	if (!kr_rank_test(rank, KR_RANK_SECURE) && eh_orig) {
+		/* If equal rank was accepted, spoofing a *single* answer would be
+		 * enough to e.g. override NS record in AUTHORITY section.
+		 * This way they would have to hit the first answer
+		 * (whenever TTL nears expiration).
+		 * Stale-serving is NOT considered, but TTL 1 would be considered
+		 * as expiring anyway, ... */
+		int32_t old_ttl = get_new_ttl(eh_orig, qry, NULL, 0, timestamp);
+		if (old_ttl > 0 && !is_expiring(eh_orig->ttl, old_ttl)
+		    && rank <= eh_orig->rank) {
+			WITH_VERBOSE(qry) {
+				auto_free char *type_str = kr_rrtype_text(type),
+					*owner_str = kr_dname_text(owner);
+				VERBOSE_MSG(qry, "=> not overwriting %s %s\n",
+						type_str, owner_str);
+			}
+			return kr_error(EEXIST);
+		}
+	}
+
+	if (!i_type) {
+		/* The non-list types are trivial now. */
+		return cache_write_or_clear(cache, &key, val_new_entry, qry);
+	}
+	/* Now we're in trouble.  In some cases, parts of data to be written
+	 * is an lmdb entry that may be invalidated by our write request.
+	 * (lmdb does even in-place updates!) Therefore we copy all into a buffer.
+	 * LATER(optim.): do this only when neccessary, or perhaps another approach.
+	 * This is also complicated by the fact that the val_new_entry part
+	 * is to be written *afterwards* by the caller.
+	 */
+	el[i_type] = (knot_db_val_t){
+		.len = val_new_entry->len,
+		.data = NULL, /* perhaps unclear in the entry_h_splice() API */
+	};
+	knot_db_val_t val = {
+		.len = entry_list_serial_size(el),
+		.data = NULL,
+	};
+	uint8_t buf[val.len];
+	entry_list_memcpy((struct entry_apex *)buf, el);
+	ret = cache_write_or_clear(cache, &key, &val, qry);
+	if (ret) return kr_error(ret);
+	memcpy(val.data, buf, val.len); /* we also copy the "empty" space, but well... */
+	val_new_entry->data = (uint8_t *)val.data
+			    + ((uint8_t *)el[i_type].data - buf);
+	return kr_ok();
+}
+
diff --git a/lib/cache/entry_pkt.c b/lib/cache/entry_pkt.c
new file mode 100644
index 0000000..4ed2047
--- /dev/null
+++ b/lib/cache/entry_pkt.c
@@ -0,0 +1,222 @@
+/*  Copyright (C) 2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+/** @file
+ * Implementation of packet-caching.  Prototypes in ./impl.h
+ *
+ * The packet is stashed in entry_h::data as uint16_t length + full packet wire format.
+ */
+
+#include "lib/utils.h"
+#include "lib/layer/iterate.h" /* kr_response_classify */
+#include "lib/cache/impl.h"
+
+
+/** Compute TTL for a packet.  Generally it's minimum TTL, with extra conditions. */
+KR_EXPORT
+uint32_t packet_ttl(const knot_pkt_t *pkt, bool is_negative)
+{
+	bool has_ttl = false;
+	uint32_t ttl = UINT32_MAX;
+	/* Find minimum entry TTL in the packet or SOA minimum TTL. */
+	for (knot_section_t i = KNOT_ANSWER; i <= KNOT_ADDITIONAL; ++i) {
+		const knot_pktsection_t *sec = knot_pkt_section(pkt, i);
+		for (unsigned k = 0; k < sec->count; ++k) {
+			const knot_rrset_t *rr = knot_pkt_rr(sec, k);
+			if (is_negative) {
+				/* Use SOA minimum TTL for negative answers. */
+				if (rr->type == KNOT_RRTYPE_SOA) {
+					return MIN(rr->ttl, knot_soa_minimum(rr->rrs.rdata));
+				} else {
+					continue; /* Use SOA only for negative answers. */
+				}
+			}
+			if (knot_rrtype_is_metatype(rr->type)) {
+				continue; /* Skip metatypes. */
+			}
+			ttl = MIN(ttl, rr->ttl);
+			has_ttl = true;
+		}
+	}
+	/* If no valid TTL present, go with zero (will get clamped to minimum). */
+	return has_ttl ? ttl : 0;
+}
+
+
+void stash_pkt(const knot_pkt_t *pkt, const struct kr_query *qry,
+		const struct kr_request *req, const bool needs_pkt)
+{
+	/* In some cases, stash also the packet. */
+	const bool is_negative = kr_response_classify(pkt)
+				& (PKT_NODATA|PKT_NXDOMAIN);
+	const struct kr_qflags * const qf = &qry->flags;
+	const bool want_negative = qf->DNSSEC_INSECURE || !qf->DNSSEC_WANT;
+	const bool want_pkt = qf->DNSSEC_BOGUS /*< useful for +cd answers */
+				|| (is_negative && want_negative) || needs_pkt;
+
+	if (!want_pkt || !knot_wire_get_aa(pkt->wire)
+	    || pkt->parsed != pkt->size /*< malformed packet; still can't detect KNOT_EFEWDATA */
+	   ) {
+		return;
+	}
+
+	/* Compute rank.  If cd bit is set or we got answer via non-validated
+	 * forwarding, make the rank bad; otherwise it depends on flags.
+	 * TODO: probably make validator attempt validation even with +cd. */
+	uint8_t rank = KR_RANK_AUTH;
+	const bool risky_vldr = is_negative && qf->FORWARD && qf->CNAME;
+		/* ^^ CNAME'ed NXDOMAIN answer in forwarding mode can contain
+		 * unvalidated records; original commit: d6e22f476. */
+	if (knot_wire_get_cd(req->qsource.packet->wire) || qf->STUB || risky_vldr) {
+		kr_rank_set(&rank, KR_RANK_OMIT);
+	} else {
+		if (qf->DNSSEC_BOGUS) {
+			kr_rank_set(&rank, KR_RANK_BOGUS);
+		} else if (qf->DNSSEC_INSECURE) {
+			kr_rank_set(&rank, KR_RANK_INSECURE);
+		} else if (!qf->DNSSEC_WANT) {
+			/* no TAs at all, leave _RANK_AUTH */
+		} else if (needs_pkt) {
+			/* All bad cases should be filtered above,
+			 * at least the same way as pktcache in kresd 1.5.x. */
+			kr_rank_set(&rank, KR_RANK_SECURE);
+		} else assert(false);
+	}
+
+	const uint16_t pkt_type = knot_pkt_qtype(pkt);
+	const knot_dname_t *owner = knot_pkt_qname(pkt); /* qname can't be compressed */
+
+	// LATER: nothing exists under NXDOMAIN.  Implement that (optionally)?
+#if 0
+	if (knot_wire_get_rcode(pkt->wire) == KNOT_RCODE_NXDOMAIN
+	 /* && !qf->DNSSEC_INSECURE */ ) {
+		pkt_type = KNOT_RRTYPE_NS;
+	}
+#endif
+
+	/* Construct the key under which the pkt will be stored. */
+	struct key k_storage, *k = &k_storage;
+	knot_db_val_t key;
+	int ret = kr_dname_lf(k->buf, owner, false);
+	if (ret) {
+		/* A server might (incorrectly) reply with QDCOUNT=0. */
+		assert(owner == NULL);
+		return;
+	}
+	key = key_exact_type_maypkt(k, pkt_type);
+
+	/* For now we stash the full packet byte-exactly as it came from upstream. */
+	const uint16_t pkt_size = pkt->size;
+	knot_db_val_t val_new_entry = {
+		.data = NULL,
+		.len = offsetof(struct entry_h, data) + sizeof(pkt_size) + pkt->size,
+	};
+	/* Prepare raw memory for the new entry and fill it. */
+	struct kr_cache *cache = &req->ctx->cache;
+	ret = entry_h_splice(&val_new_entry, rank, key, k->type, pkt_type,
+				owner, qry, cache, qry->timestamp.tv_sec);
+	if (ret) return; /* some aren't really errors */
+	assert(val_new_entry.data);
+	struct entry_h *eh = val_new_entry.data;
+	memset(eh, 0, offsetof(struct entry_h, data));
+	eh->time = qry->timestamp.tv_sec;
+	eh->ttl  = MAX(MIN(packet_ttl(pkt, is_negative), cache->ttl_max), cache->ttl_min);
+	eh->rank = rank;
+	eh->is_packet = true;
+	eh->has_optout = qf->DNSSEC_OPTOUT;
+	memcpy(eh->data, &pkt_size, sizeof(pkt_size));
+	memcpy(eh->data + sizeof(pkt_size), pkt->wire, pkt_size);
+
+	WITH_VERBOSE(qry) {
+		auto_free char *type_str = kr_rrtype_text(pkt_type),
+			*owner_str = kr_dname_text(owner);
+		VERBOSE_MSG(qry, "=> stashed packet: rank 0%.2o, TTL %d, "
+				"%s %s (%d B)\n",
+				eh->rank, eh->ttl,
+				type_str, owner_str, (int)val_new_entry.len);
+	}
+}
+
+
+int answer_from_pkt(kr_layer_t *ctx, knot_pkt_t *pkt, uint16_t type,
+		const struct entry_h *eh, const void *eh_bound, uint32_t new_ttl)
+{
+	struct kr_request *req = ctx->req;
+	struct kr_query *qry = req->current_query;
+
+	const uint16_t msgid = knot_wire_get_id(pkt->wire);
+
+	/* Ensure the wire buffer is large enough.  Strategy: fit and at least double. */
+	uint16_t pkt_len;
+	memcpy(&pkt_len, eh->data, sizeof(pkt_len));
+	if (pkt_len > pkt->max_size) {
+		pkt->max_size = MIN(KNOT_WIRE_MAX_PKTSIZE,
+				    MAX(pkt->max_size * 2, pkt_len));
+		mm_free(&ctx->req->pool, pkt->wire); /* no-op, but... */
+		pkt->wire = mm_alloc(&ctx->req->pool, pkt->max_size);
+		pkt->compr.wire = pkt->wire;
+		/* TODO: ^^ nicer way how to replace knot_pkt_t::wire ? */
+	}
+	assert(pkt->max_size >= pkt_len);
+
+	/* Copy answer and reparse it, but keep the original message id. */
+	knot_pkt_clear(pkt);
+	memcpy(pkt->wire, eh->data + 2, pkt_len);
+	pkt->size = pkt_len;
+	int ret = knot_pkt_parse(pkt, 0);
+	if (ret == KNOT_EFEWDATA || ret == KNOT_EMALF) {
+		return kr_error(ENOENT);
+		/* LATER(opt): try harder to avoid stashing such packets */
+	}
+	if (ret != KNOT_EOK) {
+		assert(!ret);
+		return kr_error(ret);
+	}
+	knot_wire_set_id(pkt->wire, msgid);
+
+	/* Add rank into the additional field. */
+	for (size_t i = 0; i < pkt->rrset_count; ++i) {
+		assert(!pkt->rr[i].additional);
+		uint8_t *rr_rank = mm_alloc(&pkt->mm, sizeof(*rr_rank));
+		if (!rr_rank) {
+			return kr_error(ENOMEM);
+		}
+		*rr_rank = eh->rank;
+		pkt->rr[i].additional = rr_rank;
+	}
+
+	/* Adjust TTL in each record. */
+	const uint32_t drift = eh->ttl - new_ttl;
+	for (knot_section_t i = KNOT_ANSWER; i <= KNOT_ADDITIONAL; ++i) {
+		const knot_pktsection_t *sec = knot_pkt_section(pkt, i);
+		for (unsigned k = 0; k < sec->count; ++k) {
+			knot_rrset_t *rrs = // vv FIXME??
+				/*const-cast*/(knot_rrset_t *)knot_pkt_rr(sec, k);
+			/* We need to be careful: due to enforcing minimum TTL
+			 * on packet, some records may be below that value.
+			 * We keep those records at TTL 0. */
+			if (rrs->ttl >= drift) {
+				rrs->ttl -= drift;
+			} else {
+				rrs->ttl = 0;
+			}
+		}
+	}
+
+	/* Finishing touches. TODO: perhaps factor out */
+	struct kr_qflags * const qf = &qry->flags;
+	qf->EXPIRING = is_expiring(eh->ttl, new_ttl);
+	qf->CACHED = true;
+	qf->NO_MINIMIZE = true;
+	qf->DNSSEC_INSECURE = kr_rank_test(eh->rank, KR_RANK_INSECURE);
+	qf->DNSSEC_BOGUS = kr_rank_test(eh->rank, KR_RANK_BOGUS);
+	if (qf->DNSSEC_INSECURE || qf->DNSSEC_BOGUS) {
+		qf->DNSSEC_WANT = false;
+	}
+	qf->DNSSEC_OPTOUT = eh->has_optout;
+	VERBOSE_MSG(qry, "=> satisfied by exact packet: rank 0%.2o, new TTL %d\n",
+			eh->rank, new_ttl);
+	return kr_ok();
+}
+
diff --git a/lib/cache/entry_rr.c b/lib/cache/entry_rr.c
new file mode 100644
index 0000000..5e7d26f
--- /dev/null
+++ b/lib/cache/entry_rr.c
@@ -0,0 +1,125 @@
+/*  Copyright (C) 2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+/** @file
+ * Implementation of RRset (de)materialization, i.e. (de)serialization to storage
+ * format used in cache (some repeated fields are omitted).  Prototypes in ./impl.h
+ */
+
+#include "lib/cache/impl.h"
+
+int rdataset_dematerialize(const knot_rdataset_t *rds, uint8_t * restrict data)
+{
+	/* FIXME: either give up on even alignment and thus direct usability
+	 * of rdatasets as they are in lmdb, or align inside cdb_* functions
+	 * (request sizes one byte longer and shift iff on an odd address). */
+	//if ((size_t)data & 1) VERBOSE_MSG(NULL, "dematerialize: odd address\n");
+	//const uint8_t *data0 = data;
+	if (!data) {
+		assert(data);
+		return kr_error(EINVAL);
+	}
+	const uint16_t rr_count = rds ? rds->count : 0;
+	memcpy(data, &rr_count, sizeof(rr_count));
+	data += sizeof(rr_count);
+	if (rr_count) {
+		memcpy(data, rds->rdata, rds->size);
+		data += rds->size;
+	}
+	//VERBOSE_MSG(NULL, "dematerialized to %d B\n", (int)(data - data0));
+	(void)data;
+	return kr_ok();
+}
+
+/** Materialize a knot_rdataset_t from cache with given TTL.
+ * Return the number of bytes consumed or an error code.
+ */
+static int rdataset_materialize(knot_rdataset_t * restrict rds, const uint8_t * const data,
+				const uint8_t *data_bound, knot_mm_t *pool)
+{
+	assert(rds && data && data_bound && data_bound > data && !rds->rdata
+		/*&& !((size_t)data & 1)*/);
+	assert(pool); /* not required, but that's our current usage; guard leaks */
+	const uint8_t *d = data; /* iterates over the cache data */
+	/* First sum up the sizes for wire format length. */
+	/* TODO: we might overrun here already, but we need to trust cache anyway...*/
+	rds->size = rdataset_dematerialized_size(d, &rds->count);
+	d += KR_CACHE_RR_COUNT_SIZE;
+	if (d + rds->size > data_bound) {
+		VERBOSE_MSG(NULL, "materialize: EILSEQ!\n");
+		return kr_error(EILSEQ);
+	}
+	if (!rds->count) { /* avoid mm_alloc(pool, 0); etc. */
+		rds->rdata = NULL;
+		return d - data;
+	}
+	rds->rdata = mm_alloc(pool, rds->size);
+	if (!rds->rdata) {
+		return kr_error(ENOMEM);
+	}
+	memcpy(rds->rdata, d, rds->size);
+	d += rds->size;
+	//VERBOSE_MSG(NULL, "materialized from %d B\n", (int)(d - data));
+	return d - data;
+}
+
+int kr_cache_materialize(knot_rdataset_t *dst, const struct kr_cache_p *ref,
+			 knot_mm_t *pool)
+{
+	struct entry_h *eh = ref->raw_data;
+	return rdataset_materialize(dst, eh->data, ref->raw_bound, pool);
+}
+
+
+int entry2answer(struct answer *ans, int id,
+		const struct entry_h *eh, const uint8_t *eh_bound,
+		const knot_dname_t *owner, uint16_t type, uint32_t new_ttl)
+{
+	/* We assume it's zeroed.  Do basic sanity check. */
+	if (ans->rrsets[id].set.rr || ans->rrsets[id].sig_rds.rdata
+	    || (type == KNOT_RRTYPE_NSEC  &&  ans->nsec_p.raw)
+	    || (type == KNOT_RRTYPE_NSEC3 && !ans->nsec_p.raw)
+	   )
+	{
+		assert(false);
+		return kr_error(EINVAL);
+	}
+	/* Materialize the base RRset. */
+	knot_rrset_t *rr = ans->rrsets[id].set.rr
+		= knot_rrset_new(owner, type, KNOT_CLASS_IN, new_ttl, ans->mm);
+	if (!rr) {
+		assert(!ENOMEM);
+		return kr_error(ENOMEM);
+	}
+	int ret = rdataset_materialize(&rr->rrs, eh->data, eh_bound, ans->mm);
+	if (ret < 0) goto fail;
+	size_t data_off = ret;
+	ans->rrsets[id].set.rank = eh->rank;
+	ans->rrsets[id].set.expiring = is_expiring(eh->ttl, new_ttl);
+	/* Materialize the RRSIG RRset for the answer in (pseudo-)packet. */
+	bool want_rrsigs = true; /* LATER(optim.): might be omitted in some cases. */
+	if (want_rrsigs) {
+		ret = rdataset_materialize(&ans->rrsets[id].sig_rds, eh->data + data_off,
+					   eh_bound, ans->mm);
+		if (ret < 0) goto fail;
+		/* Sanity check: we consumed exactly all data. */
+		int unused_bytes = eh_bound - (uint8_t *)eh->data - data_off - ret;
+		if (unused_bytes) {
+			kr_log_error("[cach] entry2answer ERROR: unused bytes: %d\n",
+					unused_bytes);
+			assert(!EILSEQ);
+			ret = kr_error(EILSEQ);
+			goto fail; /* to be on the safe side */
+		}
+	}
+	return kr_ok();
+fail:
+	assert(/*false*/!ret);
+	/* Cleanup the item that we might've (partially) written to. */
+	knot_rrset_free(ans->rrsets[id].set.rr, ans->mm);
+	knot_rdataset_clear(&ans->rrsets[id].sig_rds, ans->mm);
+	memset(&ans->rrsets[id], 0, sizeof(ans->rrsets[id]));
+	return kr_error(ret);
+}
+
diff --git a/lib/cache/impl.h b/lib/cache/impl.h
new file mode 100644
index 0000000..b884c36
--- /dev/null
+++ b/lib/cache/impl.h
@@ -0,0 +1,420 @@
+/*  Copyright (C) 2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+/** @file
+ * Header internal for cache implementation(s).
+ * Only LMDB works for now.
+ */
+#pragma once
+
+#include <stdbool.h>
+#include <stdint.h>
+
+#include <libdnssec/error.h>
+#include <libdnssec/nsec.h>
+#include <libknot/consts.h>
+#include <libknot/db/db.h>
+#include <libknot/dname.h>
+
+#include "contrib/cleanup.h"
+#include "contrib/murmurhash3/murmurhash3.h" /* hash() for nsec_p_hash() */
+#include "lib/cache/cdb_api.h"
+#include "lib/resolve.h"
+
+/* Cache entry values - binary layout.
+ *
+ * It depends on type which is recognizable by the key.
+ * Code depending on the contents of the key is marked by CACHE_KEY_DEF.
+ *
+ * 'E' entry (exact hit):
+ *	- ktype == NS: struct entry_apex - multiple types inside (NS and xNAME);
+ *	- ktype != NS: struct entry_h
+ *	    * is_packet: uint16_t length, the rest is opaque and handled by ./entry_pkt.c
+ *	    * otherwise RRset + its RRSIG set (possibly empty).
+ * '1' or '3' entry (NSEC or NSEC3)
+ *	- struct entry_h, contents is the same as for exact hit
+ *	- flags don't make sense there
+ */
+
+struct entry_h {
+	uint32_t time;	/**< The time of inception. */
+	uint32_t ttl;	/**< TTL at inception moment.  Assuming it fits into int32_t ATM. */
+	uint8_t  rank : 6;	/**< See enum kr_rank */
+	bool is_packet : 1;	/**< Negative-answer packet for insecure/bogus name. */
+	bool has_optout : 1;	/**< Only for packets; persisted DNSSEC_OPTOUT. */
+	uint8_t _pad;		/**< We need even alignment for data now. */
+	uint8_t data[];
+};
+struct entry_apex;
+
+/** Check basic consistency of entry_h for 'E' entries, not looking into ->data.
+ * (for is_packet the length of data is checked)
+ */
+KR_EXPORT
+struct entry_h * entry_h_consistent_E(knot_db_val_t data, uint16_t type);
+
+struct entry_apex * entry_apex_consistent(knot_db_val_t val);
+
+/** Consistency check, ATM common for NSEC and NSEC3. */
+static inline struct entry_h * entry_h_consistent_NSEC(knot_db_val_t data)
+{
+	/* ATM it's enough to just extend the checks for exact entries. */
+	const struct entry_h *eh = entry_h_consistent_E(data, KNOT_RRTYPE_NSEC);
+	bool ok = eh != NULL;
+	ok = ok && !eh->is_packet && !eh->has_optout;
+	return ok ? /*const-cast*/(struct entry_h *)eh : NULL;
+}
+
+static inline struct entry_h * entry_h_consistent(knot_db_val_t data, uint16_t type)
+{
+	switch (type) {
+	case KNOT_RRTYPE_NSEC:
+	case KNOT_RRTYPE_NSEC3:
+		return entry_h_consistent_NSEC(data);
+	default:
+		return entry_h_consistent_E(data, type);
+	}
+}
+
+/* nsec_p* - NSEC* chain parameters */
+
+static inline int nsec_p_rdlen(const uint8_t *rdata)
+{
+	//TODO: do we really need the zero case?
+	return rdata ? 5 + rdata[4] : 0; /* rfc5155 4.2 and 3.2. */
+}
+static const int NSEC_P_MAXLEN = sizeof(uint32_t) + 5 + 255; // TODO: remove??
+
+/** Hash of NSEC3 parameters, used as a tag to separate different chains for same zone. */
+typedef uint32_t nsec_p_hash_t;
+static inline nsec_p_hash_t nsec_p_mkHash(const uint8_t *nsec_p)
+{
+	assert(nsec_p && !(KNOT_NSEC3_FLAG_OPT_OUT & nsec_p[1]));
+	return hash((const char *)nsec_p, nsec_p_rdlen(nsec_p));
+}
+
+/** NSEC* parameters for the chain. */
+struct nsec_p {
+	const uint8_t *raw; /**< Pointer to raw NSEC3 parameters; NULL for NSEC. */
+	nsec_p_hash_t hash; /**< Hash of `raw`, used for cache keys. */
+	dnssec_nsec3_params_t libknot; /**< Format for libknot; owns malloced memory! */
+};
+
+
+
+/** LATER(optim.): this is overshot, but struct key usage should be cheap ATM. */
+#define KR_CACHE_KEY_MAXLEN (KNOT_DNAME_MAXLEN + 100) /* CACHE_KEY_DEF */
+
+struct key {
+	const knot_dname_t *zname; /**< current zone name (points within qry->sname) */
+	uint8_t zlf_len; /**< length of current zone's lookup format */
+
+	/** Corresponding key type; e.g. NS for CNAME.
+	 * Note: NSEC type is ambiguous (exact and range key). */
+	uint16_t type;
+	/** The key data start at buf+1, and buf[0] contains some length.
+	 * For details see key_exact* and key_NSEC* functions. */
+	uint8_t buf[KR_CACHE_KEY_MAXLEN];
+	/* LATER(opt.): ^^ probably change the anchoring, so that kr_dname_lf()
+	 * doesn't need to move data after knot_dname_lf(). */
+};
+
+static inline size_t key_nwz_off(const struct key *k)
+{
+	/* CACHE_KEY_DEF: zone name lf + 0 ('1' or '3').
+	 * NSEC '1' case continues just with the name within zone. */
+	return k->zlf_len + 2;
+}
+static inline size_t key_nsec3_hash_off(const struct key *k)
+{
+	/* CACHE_KEY_DEF NSEC3: tag (nsec_p_hash_t) + 20 bytes NSEC3 name hash) */
+	return key_nwz_off(k) + sizeof(nsec_p_hash_t);
+}
+/** Hash is always SHA1; I see no plans to standardize anything else.
+ * https://www.iana.org/assignments/dnssec-nsec3-parameters/dnssec-nsec3-parameters.xhtml#dnssec-nsec3-parameters-3
+ */
+static const int NSEC3_HASH_LEN = 20,
+		 NSEC3_HASH_TXT_LEN = 32;
+
+/** Finish constructing string key for for exact search.
+ * It's assumed that kr_dname_lf(k->buf, owner, *) had been ran.
+ */
+knot_db_val_t key_exact_type_maypkt(struct key *k, uint16_t type);
+
+/** Like key_exact_type_maypkt but with extra checks if used for RRs only. */
+static inline knot_db_val_t key_exact_type(struct key *k, uint16_t type)
+{
+	switch (type) {
+	/* Sanity check: forbidden types represented in other way(s). */
+	case KNOT_RRTYPE_NSEC:
+	case KNOT_RRTYPE_NSEC3:
+		assert(false);
+		return (knot_db_val_t){ NULL, 0 };
+	}
+	return key_exact_type_maypkt(k, type);
+}
+
+
+/* entry_h chaining; implementation in ./entry_list.c */
+
+enum { ENTRY_APEX_NSECS_CNT = 2 };
+
+/** Header of 'E' entry with ktype == NS.  Inside is private to ./entry_list.c
+ *
+ * We store xNAME at NS type to lower the number of searches in closest_NS().
+ * CNAME is only considered for equal name, of course.
+ * We also store NSEC* parameters at NS type.
+ */
+struct entry_apex {
+	/* ENTRY_H_FLAGS */
+	bool has_ns : 1;
+	bool has_cname : 1;
+	bool has_dname : 1;
+
+	uint8_t pad_; /**< Weird: 1 byte + 2 bytes + x bytes; let's do 2+2+x. */
+	int8_t nsecs[ENTRY_APEX_NSECS_CNT]; /**< values:  0: none, 1: NSEC, 3: NSEC3 */
+	uint8_t data[];
+	/* XXX: if not first, stamp of last being the first?
+	 * Purpose: save cache operations if rolled the algo/params long ago. */
+};
+
+/** Indices for decompressed entry_list_t. */
+enum EL {
+	EL_NS = ENTRY_APEX_NSECS_CNT,
+	EL_CNAME,
+	EL_DNAME,
+	EL_LENGTH
+};
+/** Decompressed entry_apex.  It's an array of unparsed entry_h references.
+ * Note: arrays are passed "by reference" to functions (in C99). */
+typedef knot_db_val_t entry_list_t[EL_LENGTH];
+
+static inline uint16_t EL2RRTYPE(enum EL i)
+{
+	switch (i) {
+	case EL_NS:	return KNOT_RRTYPE_NS;
+	case EL_CNAME:	return KNOT_RRTYPE_CNAME;
+	case EL_DNAME:	return KNOT_RRTYPE_DNAME;
+	default:	assert(false);  return 0;
+	}
+}
+
+/** There may be multiple entries within, so rewind `val` to the one we want.
+ *
+ * ATM there are multiple types only for the NS ktype - it also accommodates xNAMEs.
+ * \note `val->len` represents the bound of the whole list, not of a single entry.
+ * \note in case of ENOENT, `val` is still rewound to the beginning of the next entry.
+ * \return error code
+ * TODO: maybe get rid of this API?
+ */
+int entry_h_seek(knot_db_val_t *val, uint16_t type);
+
+/** Prepare space to insert an entry.
+ *
+ * Some checks are performed (rank, TTL), the current entry in cache is copied
+ * with a hole ready for the new entry (old one of the same type is cut out).
+ *
+ * \param val_new_entry The only changing parameter; ->len is read, ->data written.
+ * \return error code
+ */
+int entry_h_splice(
+	knot_db_val_t *val_new_entry, uint8_t rank,
+	const knot_db_val_t key, const uint16_t ktype, const uint16_t type,
+	const knot_dname_t *owner/*log only*/,
+	const struct kr_query *qry, struct kr_cache *cache, uint32_t timestamp);
+
+/** Parse an entry_apex into individual items.  @return error code. */
+KR_EXPORT int entry_list_parse(const knot_db_val_t val, entry_list_t list);
+
+static inline size_t to_even(size_t n)
+{
+	return n + (n & 1);
+}
+
+static inline int entry_list_serial_size(const entry_list_t list)
+{
+	int size = offsetof(struct entry_apex, data);
+	for (int i = 0; i < EL_LENGTH; ++i) {
+		size += to_even(list[i].len);
+	}
+	return size;
+}
+
+/** Fill contents of an entry_apex.
+ *
+ * @note NULL pointers are overwritten - caller may like to fill the space later.
+ */
+void entry_list_memcpy(struct entry_apex *ea, entry_list_t list);
+
+
+
+/* Packet caching; implementation in ./entry_pkt.c */
+
+/** Stash the packet into cache (if suitable, etc.)
+ * \param needs_pkt we need the packet due to not stashing some RRs;
+ * 		see stash_rrset() for details
+ * It assumes check_dname_for_lf(). */
+void stash_pkt(const knot_pkt_t *pkt, const struct kr_query *qry,
+		const struct kr_request *req, bool needs_pkt);
+
+/** Try answering from packet cache, given an entry_h.
+ *
+ * This assumes the TTL is OK and entry_h_consistent, but it may still return error.
+ * On success it handles all the rest, incl. qry->flags.
+ */
+int answer_from_pkt(kr_layer_t *ctx, knot_pkt_t *pkt, uint16_t type,
+		const struct entry_h *eh, const void *eh_bound, uint32_t new_ttl);
+
+
+/** Record is expiring if it has less than 1% TTL (or less than 5s) */
+static inline bool is_expiring(uint32_t orig_ttl, uint32_t new_ttl)
+{
+	int64_t nttl = new_ttl; /* avoid potential over/under-flow */
+	return 100 * (nttl - 5) < orig_ttl;
+}
+
+/** Returns signed result so you can inspect how much stale the RR is.
+ *
+ * @param owner name for stale-serving decisions.  You may pass NULL to disable stale.
+ * @note: NSEC* uses zone name ATM; for NSEC3 the owner may not even be knowable.
+ * @param type for stale-serving.
+ */
+int32_t get_new_ttl(const struct entry_h *entry, const struct kr_query *qry,
+                    const knot_dname_t *owner, uint16_t type, uint32_t now);
+
+
+/* RRset (de)materialization; implementation in ./entry_rr.c */
+
+/** Size of the RR count field */
+#define KR_CACHE_RR_COUNT_SIZE sizeof(uint16_t)
+
+/** Compute size of serialized rdataset.  NULL is accepted as empty set. */
+static inline int rdataset_dematerialize_size(const knot_rdataset_t *rds)
+{
+	return KR_CACHE_RR_COUNT_SIZE + (rds == NULL ? 0 : rds->size);
+}
+
+/** Analyze the length of a dematerialized rdataset.
+ * Note that in the data it's KR_CACHE_RR_COUNT_SIZE and then this returned size. */
+static inline int rdataset_dematerialized_size(const uint8_t *data, uint16_t *rdataset_count)
+{
+	uint16_t count;
+	assert(sizeof(count) == KR_CACHE_RR_COUNT_SIZE);
+	memcpy(&count, data, sizeof(count));
+	const uint8_t *rdata = data + sizeof(count);
+	if (rdataset_count)
+		*rdataset_count = count;
+	for (int i = 0; i < count; ++i)
+		rdata += knot_rdata_size(((knot_rdata_t *)rdata)->len);
+	return rdata - (data + sizeof(count));
+}
+
+/** Serialize an rdataset. */
+int rdataset_dematerialize(const knot_rdataset_t *rds, uint8_t * restrict data);
+
+
+/** Partially constructed answer when gathering RRsets from cache. */
+struct answer {
+	int rcode;		/**< PKT_NODATA, etc. */
+	struct nsec_p nsec_p;	/**< Don't mix different NSEC* parameters in one answer. */
+	knot_mm_t *mm;		/**< Allocator for rrsets */
+	struct answer_rrset {
+		ranked_rr_array_entry_t set;	/**< set+rank for the main data */
+		knot_rdataset_t sig_rds;	/**< RRSIG data, if any */
+	} rrsets[1+1+3]; /**< see AR_ANSWER and friends; only required records are filled */
+};
+enum {
+	AR_ANSWER = 0, /**< Positive answer record.  It might be wildcard-expanded. */
+	AR_SOA,  /**< SOA record. */
+	AR_NSEC, /**< NSEC* covering or matching the SNAME (next closer name in NSEC3 case). */
+	AR_WILD, /**< NSEC* covering or matching the source of synthesis. */
+	AR_CPE,  /**< NSEC3 matching the closest provable encloser. */
+};
+
+/** Materialize RRset + RRSIGs into ans->rrsets[id].
+ * LATER(optim.): it's slightly wasteful that we allocate knot_rrset_t for the packet
+ *
+ * \return error code.  They are all bad conditions and "guarded" by assert.
+ */
+int entry2answer(struct answer *ans, int id,
+		const struct entry_h *eh, const uint8_t *eh_bound,
+		const knot_dname_t *owner, uint16_t type, uint32_t new_ttl);
+
+
+/* Preparing knot_pkt_t for cache answer from RRs; implementation in ./knot_pkt.c */
+
+/** Prepare answer packet to be filled by RRs (without RR data in wire). */
+int pkt_renew(knot_pkt_t *pkt, const knot_dname_t *name, uint16_t type);
+
+/** Append RRset + its RRSIGs into the current section (*shallow* copy), with given rank.
+ * \note it works with empty set as well (skipped)
+ * \note pkt->wire is not updated in any way
+ * \note KNOT_CLASS_IN is assumed
+ */
+int pkt_append(knot_pkt_t *pkt, const struct answer_rrset *rrset, uint8_t rank);
+
+
+
+/* NSEC (1) stuff.  Implementation in ./nsec1.c */
+
+/** Construct a string key for for NSEC (1) predecessor-search.
+ * \param add_wildcard Act as if the name was extended by "*."
+ * \note k->zlf_len is assumed to have been correctly set */
+knot_db_val_t key_NSEC1(struct key *k, const knot_dname_t *name, bool add_wildcard);
+
+/** Closest encloser check for NSEC (1).
+ * To understand the interface, see the call point.
+ * \param k	space to store key + input: zname and zlf_len
+ * \return 0: success;  >0: try other (NSEC3);  <0: exit cache immediately. */
+int nsec1_encloser(struct key *k, struct answer *ans,
+		   const int sname_labels, int *clencl_labels,
+		   knot_db_val_t *cover_low_kwz, knot_db_val_t *cover_hi_kwz,
+		   const struct kr_query *qry, struct kr_cache *cache);
+
+/** Source of synthesis (SS) check for NSEC (1).
+ * To understand the interface, see the call point.
+ * \return 0: continue; <0: exit cache immediately;
+ * 	AR_SOA: skip to adding SOA (SS was covered or matched for NODATA). */
+int nsec1_src_synth(struct key *k, struct answer *ans, const knot_dname_t *clencl_name,
+		    knot_db_val_t cover_low_kwz, knot_db_val_t cover_hi_kwz,
+		    const struct kr_query *qry, struct kr_cache *cache);
+
+
+/* NSEC3 stuff.  Implementation in ./nsec3.c */
+
+/** Construct a string key for for NSEC3 predecessor-search, from an NSEC3 name.
+ * \note k->zlf_len is assumed to have been correctly set */
+knot_db_val_t key_NSEC3(struct key *k, const knot_dname_t *nsec3_name,
+			const nsec_p_hash_t nsec_p_hash);
+
+/** TODO.  See nsec1_encloser(...) */
+int nsec3_encloser(struct key *k, struct answer *ans,
+		   const int sname_labels, int *clencl_labels,
+		   const struct kr_query *qry, struct kr_cache *cache);
+
+/** TODO.  See nsec1_src_synth(...) */
+int nsec3_src_synth(struct key *k, struct answer *ans, const knot_dname_t *clencl_name,
+		    const struct kr_query *qry, struct kr_cache *cache);
+
+
+
+#define VERBOSE_MSG(qry, ...) QRVERBOSE((qry), "cach",  ## __VA_ARGS__)
+
+/** Shorthand for operations on cache backend */
+#define cache_op(cache, op, ...) (cache)->api->op((cache)->db, &(cache)->stats, ## __VA_ARGS__)
+
+
+static inline uint16_t get_uint16(const void *address)
+{
+	uint16_t tmp;
+	memcpy(&tmp, address, sizeof(tmp));
+	return tmp;
+}
+
+/** Useful pattern, especially as void-pointer arithmetic isn't standard-compliant. */
+static inline uint8_t * knot_db_val_bound(knot_db_val_t val)
+{
+	return (uint8_t *)val.data + val.len;
+}
+
diff --git a/lib/cache/knot_pkt.c b/lib/cache/knot_pkt.c
new file mode 100644
index 0000000..d913c5d
--- /dev/null
+++ b/lib/cache/knot_pkt.c
@@ -0,0 +1,93 @@
+/*  Copyright (C) 2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+/** @file
+ * Implementation of preparing knot_pkt_t for filling with RRs.
+ * Prototypes in ./impl.h
+ */
+
+#include "lib/cache/impl.h"
+
+int pkt_renew(knot_pkt_t *pkt, const knot_dname_t *name, uint16_t type)
+{
+	/* Update packet question if needed. */
+	if (!knot_dname_is_equal(knot_pkt_qname(pkt), name)
+	    || knot_pkt_qtype(pkt) != type || knot_pkt_qclass(pkt) != KNOT_CLASS_IN) {
+		int ret = kr_pkt_recycle(pkt);
+		if (ret) return kr_error(ret);
+		ret = knot_pkt_put_question(pkt, name, KNOT_CLASS_IN, type);
+		if (ret) return kr_error(ret);
+	}
+
+	pkt->parsed = pkt->size = PKT_SIZE_NOWIRE;
+	knot_wire_set_qr(pkt->wire);
+	knot_wire_set_aa(pkt->wire);
+	return kr_ok();
+}
+
+/** Reserve space for additional `count` RRsets.
+ * \note pkt->rr_info gets correct length but is always zeroed
+ */
+static int pkt_alloc_space(knot_pkt_t *pkt, int count)
+{
+	size_t allocd_orig = pkt->rrset_allocd;
+	if (pkt->rrset_count + count <= allocd_orig) {
+		return kr_ok();
+	}
+	/* A simple growth strategy, amortized O(count). */
+	pkt->rrset_allocd = MAX(
+			pkt->rrset_count + count,
+			pkt->rrset_count + allocd_orig);
+
+	pkt->rr = mm_realloc(&pkt->mm, pkt->rr,
+				sizeof(pkt->rr[0]) * pkt->rrset_allocd,
+				sizeof(pkt->rr[0]) * allocd_orig);
+	if (!pkt->rr) {
+		return kr_error(ENOMEM);
+	}
+	/* Allocate pkt->rr_info to be certain, but just leave it zeroed. */
+	mm_free(&pkt->mm, pkt->rr_info);
+	pkt->rr_info = mm_calloc(&pkt->mm, pkt->rrset_allocd, sizeof(pkt->rr_info[0]));
+	if (!pkt->rr_info) {
+		return kr_error(ENOMEM);
+	}
+	return kr_ok();
+}
+
+int pkt_append(knot_pkt_t *pkt, const struct answer_rrset *rrset, uint8_t rank)
+{
+	/* allocate space, to be sure */
+	int rrset_cnt = (rrset->set.rr->rrs.count > 0) + (rrset->sig_rds.count > 0);
+	int ret = pkt_alloc_space(pkt, rrset_cnt);
+	if (ret) return kr_error(ret);
+	/* write both sets */
+	const knot_rdataset_t *rdss[2] = { &rrset->set.rr->rrs, &rrset->sig_rds };
+	for (int i = 0; i < rrset_cnt; ++i) {
+		assert(rdss[i]->count);
+		/* allocate rank */
+		uint8_t *rr_rank = mm_alloc(&pkt->mm, sizeof(*rr_rank));
+		if (!rr_rank) return kr_error(ENOMEM);
+		*rr_rank = (i == 0) ? rank : (KR_RANK_OMIT | KR_RANK_AUTH);
+			/* rank for RRSIGs isn't really useful: ^^ */
+		if (i == 0) {
+			pkt->rr[pkt->rrset_count] = *rrset->set.rr;
+			pkt->rr[pkt->rrset_count].additional = rr_rank;
+		} else {
+		/* append the RR array */
+			pkt->rr[pkt->rrset_count] = (knot_rrset_t){
+				.owner = knot_dname_copy(rrset->set.rr->owner, &pkt->mm),
+					/* ^^ well, another copy isn't really needed */
+				.ttl = rrset->set.rr->ttl,
+				.type = KNOT_RRTYPE_RRSIG,
+				.rclass = KNOT_CLASS_IN,
+				.rrs = *rdss[i],
+				.additional = rr_rank,
+			};
+		}
+		++pkt->rrset_count;
+		++(pkt->sections[pkt->current].count);
+	}
+	return kr_ok();
+}
+
diff --git a/lib/cache/nsec1.c b/lib/cache/nsec1.c
new file mode 100644
index 0000000..3985ca3
--- /dev/null
+++ b/lib/cache/nsec1.c
@@ -0,0 +1,499 @@
+/*  Copyright (C) 2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+/** @file
+ * Implementation of NSEC (1) handling.  Prototypes in ./impl.h
+ */
+
+#include "lib/cache/impl.h"
+#include "lib/dnssec/nsec.h"
+#include "lib/layer/iterate.h"
+
+
+/** Reconstruct a name into a buffer (assuming length at least KNOT_DNAME_MAXLEN).
+ * \return kr_ok() or error code (<0). */
+static int dname_wire_reconstruct(knot_dname_t *buf, const struct key *k,
+		 knot_db_val_t kwz)
+{
+	/* Reconstruct from key: first the ending, then zone name. */
+	int ret = knot_dname_lf2wire(buf, kwz.len, kwz.data);
+	if (ret < 0) {
+		VERBOSE_MSG(NULL, "=> NSEC: LF2wire ret = %d\n", ret);
+		assert(false);
+		return ret;
+	}
+		/* The last written byte is the zero label for root -> overwrite. */
+	knot_dname_t *zone_start = buf + ret - 1;
+	assert(*zone_start == '\0');
+	ret = knot_dname_to_wire(zone_start, k->zname, KNOT_DNAME_MAXLEN - kwz.len);
+	if (ret != k->zlf_len + 1) {
+		assert(false);
+		return ret < 0 ? ret : kr_error(EILSEQ);
+	}
+	return kr_ok();
+}
+
+
+knot_db_val_t key_NSEC1(struct key *k, const knot_dname_t *name, bool add_wildcard)
+{
+	/* we basically need dname_lf with two bytes added
+	 * on a correct place within the name (the cut) */
+	int ret;
+	const bool ok = k && name
+		&& !(ret = kr_dname_lf(k->buf, name, add_wildcard));
+	if (!ok) {
+		assert(false);
+		return (knot_db_val_t){ NULL, 0 };
+	}
+
+	uint8_t *begin = k->buf + 1 + k->zlf_len; /* one byte after zone's zero */
+	uint8_t *end = k->buf + 1 + k->buf[0]; /* we don't use the final zero in key,
+						* but move it anyway */
+	if (end < begin) {
+		assert(false);
+		return (knot_db_val_t){ NULL, 0 };
+	}
+	int key_len;
+	if (end > begin) {
+		memmove(begin + 2, begin, end - begin);
+		key_len = k->buf[0] + 1;
+	} else {
+		key_len = k->buf[0] + 2;
+	}
+	/* CACHE_KEY_DEF: key == zone's dname_lf + '\0' + '1' + dname_lf
+	 * of the name within the zone without the final 0.  Iff the latter is empty,
+	 * there's no zero to cut and thus the key_len difference.
+	 */
+	begin[0] = 0;
+	begin[1] = '1'; /* tag for NSEC1 */
+	k->type = KNOT_RRTYPE_NSEC;
+
+	/*
+	VERBOSE_MSG(NULL, "<> key_NSEC1; name: ");
+	kr_dname_print(name, add_wildcard ? "*." : "" , " ");
+	kr_log_verbose("(zone name LF length: %d; total key length: %d)\n",
+			k->zlf_len, key_len);
+	*/
+
+	return (knot_db_val_t){ k->buf + 1, key_len };
+}
+
+
+/** Assuming that k1 < k4, find where k2 is.  (Considers DNS wrap-around.)
+ *
+ * \return Intuition: position of k2 among kX.
+ *	0: k2 < k1;  1: k1 == k2;  2: k1 is a prefix of k2 < k4;
+ *	3: k1 < k2 < k4 (and not 2);  4: k2 == k4;  5: k2 > k4
+ * \note k1.data may be NULL, meaning assumption that k1 < k2 and not a prefix
+ *       (i.e. return code will be > 2)
+ */
+static int kwz_between(knot_db_val_t k1, knot_db_val_t k2, knot_db_val_t k4)
+{
+	assert(k2.data && k4.data);
+	/* CACHE_KEY_DEF; we need to beware of one key being a prefix of another */
+	int ret_maybe; /**< result, assuming we confirm k2 < k4 */
+	if (k1.data) {
+		const int cmp12 = memcmp(k1.data, k2.data, MIN(k1.len, k2.len));
+		if (cmp12 == 0 && k1.len == k2.len) /* iff k1 == k2 */
+			return 1;
+		if (cmp12 > 0 || (cmp12 == 0 && k1.len > k2.len)) /* iff k1 > k2 */
+			return 0;
+		ret_maybe = cmp12 == 0 ? 2 : 3;
+	} else {
+		ret_maybe = 3;
+	}
+	if (k4.len == 0) { /* wrap-around */
+		return k2.len > 0 ? ret_maybe : 4;
+	} else {
+		const int cmp24 = memcmp(k2.data, k4.data, MIN(k2.len, k4.len));
+		if (cmp24 == 0 && k2.len == k4.len) /* iff k2 == k4 */
+			return 4;
+		if (cmp24 > 0 || (cmp24 == 0 && k2.len > k4.len)) /* iff k2 > k4 */
+			return 5;
+		return ret_maybe;
+	}
+}
+
+
+/** NSEC1 range search.
+ *
+ * \param key Pass output of key_NSEC1(k, ...)
+ * \param value[out] The raw data of the NSEC cache record (optional; consistency checked).
+ * \param exact_match[out] Whether the key was matched exactly or just covered (optional).
+ * \param kwz_low[out] Output the low end of covering NSEC, pointing within DB (optional).
+ * \param kwz_high[in,out] Storage for the high end of covering NSEC (optional).
+ * 		It's only set if !exact_match.
+ * \param new_ttl[out] New TTL of the NSEC (optional).
+ * \return Error message or NULL.
+ * \note The function itself does *no* bitmap checks, e.g. RFC 6840 sec. 4.
+ */
+static const char * find_leq_NSEC1(struct kr_cache *cache, const struct kr_query *qry,
+			const knot_db_val_t key, const struct key *k, knot_db_val_t *value,
+			bool *exact_match, knot_db_val_t *kwz_low, knot_db_val_t *kwz_high,
+			uint32_t *new_ttl)
+{
+	/* Do the cache operation. */
+	const size_t nwz_off = key_nwz_off(k);
+	if (!key.data || key.len < nwz_off) {
+		assert(false);
+		return "range search ERROR";
+	}
+	knot_db_val_t key_nsec = key;
+	knot_db_val_t val = { NULL, 0 };
+	int ret = cache_op(cache, read_leq, &key_nsec, &val);
+	if (ret < 0) {
+		if (ret == kr_error(ENOENT)) {
+			return "range search miss";
+		} else {
+			assert(false);
+			return "range search ERROR";
+		}
+	}
+	if (value) {
+		*value = val;
+	}
+	/* Check consistency, TTL, rank. */
+	const bool is_exact = (ret == 0);
+	if (exact_match) {
+		*exact_match = is_exact;
+	}
+	const struct entry_h *eh = entry_h_consistent_NSEC(val);
+	if (!eh) {
+		/* This might be just finding something else than NSEC1 entry,
+		 * in case we searched before the very first one in the zone. */
+		return "range search found inconsistent entry";
+	}
+	/* Passing just zone name instead of owner, as we don't
+	 * have it reconstructed at this point. */
+	int32_t new_ttl_ = get_new_ttl(eh, qry, k->zname, KNOT_RRTYPE_NSEC,
+					qry->timestamp.tv_sec);
+	if (new_ttl_ < 0 || !kr_rank_test(eh->rank, KR_RANK_SECURE)) {
+		return "range search found stale or insecure entry";
+		/* TODO: remove the stale record *and* retry,
+		 * in case we haven't run off.  Perhaps start by in_zone check. */
+	}
+	if (new_ttl) {
+		*new_ttl = new_ttl_;
+	}
+	if (kwz_low) {
+		*kwz_low = (knot_db_val_t){
+			.data = (uint8_t *)key_nsec.data + nwz_off,
+			.len = key_nsec.len - nwz_off,
+		};	/* CACHE_KEY_DEF */
+	}
+	if (is_exact) {
+		/* Nothing else to do. */
+		return NULL;
+	}
+	/* The NSEC starts strictly before our target name;
+	 * now check that it still belongs into that zone. */
+	const bool nsec_in_zone = key_nsec.len >= nwz_off
+		/* CACHE_KEY_DEF */
+		&& memcmp(key.data, key_nsec.data, nwz_off) == 0;
+	if (!nsec_in_zone) {
+		return "range search miss (!nsec_in_zone)";
+	}
+	/* We know it starts before sname, so let's check the other end.
+	 * 1. construct the key for the next name - kwz_hi. */
+	/* it's *full* name ATM */
+	const knot_rdata_t *next = (const knot_rdata_t *)
+				(eh->data + KR_CACHE_RR_COUNT_SIZE);
+	if (KR_CACHE_RR_COUNT_SIZE != 2 || get_uint16(eh->data) == 0) {
+		assert(false);
+		return "ERROR";
+		/* TODO: more checks? */
+	}
+	/*
+	WITH_VERBOSE {
+		VERBOSE_MSG(qry, "=> NSEC: next name: ");
+		kr_dname_print(next, "", "\n");
+	}
+	*/
+	knot_dname_t ch_buf[KNOT_DNAME_MAXLEN];
+	knot_dname_t *chs = kwz_high ? kwz_high->data : ch_buf;
+	if (!chs) {
+		assert(false);
+		return "EINVAL";
+	}
+	{
+		/* Lower-case chs; see also RFC 6840 5.1.
+		 * LATER(optim.): we do lots of copying etc. */
+		knot_dname_t lower_buf[KNOT_DNAME_MAXLEN];
+		ret = knot_dname_to_wire(lower_buf, next->data,
+					 MIN(next->len, KNOT_DNAME_MAXLEN));
+		if (ret < 0) { /* _ESPACE */
+			return "range search found record with incorrect contents";
+		}
+		knot_dname_to_lower(lower_buf);
+		ret = kr_dname_lf(chs, lower_buf, false);
+	}
+	if (ret) {
+		assert(false);
+		return "ERROR";
+	}
+	knot_db_val_t kwz_hi = { /* skip the zone name */
+		.data = chs + 1 + k->zlf_len,
+		.len = chs[0] - k->zlf_len,
+	};
+	assert((ssize_t)(kwz_hi.len) >= 0);
+	/* 2. do the actual range check. */
+	const knot_db_val_t kwz_sname = {
+		.data = (void *)/*const-cast*/(k->buf + 1 + nwz_off),
+		.len = k->buf[0] - k->zlf_len,
+	};
+	assert((ssize_t)(kwz_sname.len) >= 0);
+	bool covers = /* we know for sure that the low end is before kwz_sname */
+		3 == kwz_between((knot_db_val_t){ NULL, 0 }, kwz_sname, kwz_hi);
+	if (!covers) {
+		return "range search miss (!covers)";
+	}
+	if (kwz_high) {
+		*kwz_high = kwz_hi;
+	}
+	return NULL;
+}
+
+
+int nsec1_encloser(struct key *k, struct answer *ans,
+		   const int sname_labels, int *clencl_labels,
+		   knot_db_val_t *cover_low_kwz, knot_db_val_t *cover_hi_kwz,
+		   const struct kr_query *qry, struct kr_cache *cache)
+{
+	static const int ESKIP = ABS(ENOENT);
+	/* Basic sanity check. */
+	const bool ok = k && ans && clencl_labels && cover_low_kwz && cover_hi_kwz
+			&& qry && cache;
+	if (!ok) {
+		assert(!EINVAL);
+		return kr_error(EINVAL);
+	}
+	
+	/* Find a previous-or-equal name+NSEC in cache covering the QNAME,
+	 * checking TTL etc. */
+	knot_db_val_t key = key_NSEC1(k, qry->sname, false);
+	knot_db_val_t val = { NULL, 0 };
+	bool exact_match;
+	uint32_t new_ttl;
+	const char *err = find_leq_NSEC1(cache, qry, key, k, &val,
+			&exact_match, cover_low_kwz, cover_hi_kwz, &new_ttl);
+	if (err) {
+		VERBOSE_MSG(qry, "=> NSEC sname: %s\n", err);
+		return ESKIP;
+	}
+
+	/* Get owner name of the record. */
+	const knot_dname_t *owner;
+	knot_dname_t owner_buf[KNOT_DNAME_MAXLEN];
+	if (exact_match) {
+		owner = qry->sname;
+	} else {
+		int ret = dname_wire_reconstruct(owner_buf, k, *cover_low_kwz);
+		if (unlikely(ret)) return ESKIP;
+		owner = owner_buf;
+	}
+	/* Basic checks OK -> materialize data. */
+	{
+		const struct entry_h *nsec_eh = val.data;
+		int ret = entry2answer(ans, AR_NSEC, nsec_eh, knot_db_val_bound(val),
+					owner, KNOT_RRTYPE_NSEC, new_ttl);
+		if (ret) return kr_error(ret);
+	}
+
+	/* Final checks, split for matching vs. covering our sname. */
+	const knot_rrset_t *nsec_rr = ans->rrsets[AR_NSEC].set.rr;
+	const uint8_t *bm = knot_nsec_bitmap(nsec_rr->rrs.rdata);
+	uint16_t bm_size = knot_nsec_bitmap_len(nsec_rr->rrs.rdata);
+	assert(bm);
+
+	if (exact_match) {
+		if (kr_nsec_bitmap_nodata_check(bm, bm_size, qry->stype, nsec_rr->owner) != 0) {
+			VERBOSE_MSG(qry,
+				"=> NSEC sname: match but failed type check\n");
+			return ESKIP;
+		}
+		/* NODATA proven; just need to add SOA+RRSIG later */
+		VERBOSE_MSG(qry, "=> NSEC sname: match proved NODATA, new TTL %d\n",
+				new_ttl);
+		ans->rcode = PKT_NODATA;
+		return kr_ok();
+	} /* else */
+
+	/* Inexact match.  First check if sname is delegated by that NSEC. */
+	const int nsec_matched = knot_dname_matched_labels(nsec_rr->owner, qry->sname);
+	const bool is_sub = nsec_matched == knot_dname_labels(nsec_rr->owner, NULL);
+	if (is_sub && kr_nsec_children_in_zone_check(bm, bm_size) != 0) {
+		VERBOSE_MSG(qry, "=> NSEC sname: covered but delegated (or error)\n");
+		return ESKIP;
+	}
+	/* NXDOMAIN proven *except* for wildcards. */
+	WITH_VERBOSE(qry) {
+		auto_free char *owner_str = kr_dname_text(nsec_rr->owner),
+			  *next_str = kr_dname_text(knot_nsec_next(nsec_rr->rrs.rdata));
+		VERBOSE_MSG(qry, "=> NSEC sname: covered by: %s -> %s, new TTL %d\n",
+				owner_str, next_str, new_ttl);
+	}
+
+	/* Find label count of the closest encloser.
+	 * Both endpoints in an NSEC do exist (though possibly in a child zone)
+	 * and any prefixes of those names as well (empty non-terminals),
+	 * but nothing else exists inside this "triangle".
+	 *
+	 * Note that we have to lower-case the next name for comparison,
+	 * even though we have canonicalized NSEC already; see RFC 6840 5.1.
+	 * LATER(optim.): it might be faster to use the LFs we already have.
+	 */
+	knot_dname_t next[KNOT_DNAME_MAXLEN];
+	int ret = knot_dname_to_wire(next, knot_nsec_next(nsec_rr->rrs.rdata), sizeof(next));
+	if (ret < 0) {
+		assert(!ret);
+		return kr_error(ret);
+	}
+	knot_dname_to_lower(next);
+	*clencl_labels = MAX(
+		nsec_matched,
+		knot_dname_matched_labels(qry->sname, next)
+		);
+
+	/* Empty non-terminals don't need to have
+	 * a matching NSEC record. */
+	if (sname_labels == *clencl_labels) {
+		ans->rcode = PKT_NODATA;
+		VERBOSE_MSG(qry,
+			"=> NSEC sname: empty non-terminal by the same RR\n");
+	} else {
+		ans->rcode = PKT_NXDOMAIN;
+	}
+	return kr_ok();
+}
+
+/** Verify non-existence after kwz_between() call. */
+static bool nonexistence_ok(int cmp, const knot_rrset_t *rrs)
+{
+	if (cmp == 3) {
+		return true;
+	}
+	if (cmp != 2) {
+		return false;
+	}
+	const uint8_t *bm = knot_nsec_bitmap(rrs->rrs.rdata);
+	uint16_t bm_size = knot_nsec_bitmap_len(rrs->rrs.rdata);
+	return kr_nsec_children_in_zone_check(bm, bm_size) != 0;
+}
+
+int nsec1_src_synth(struct key *k, struct answer *ans, const knot_dname_t *clencl_name,
+		    knot_db_val_t cover_low_kwz, knot_db_val_t cover_hi_kwz,
+		    const struct kr_query *qry, struct kr_cache *cache)
+{
+	/* Construct key for the source of synthesis. */
+	knot_db_val_t key = key_NSEC1(k, clencl_name, true);
+	const size_t nwz_off = key_nwz_off(k);
+	if (!key.data || key.len < nwz_off) {
+		assert(false);
+		return kr_error(1);
+	}
+	/* Check if our sname-covering NSEC also covers/matches SS. */
+	knot_db_val_t kwz = {
+		.data = (uint8_t *)key.data + nwz_off,
+		.len = key.len - nwz_off,
+	};
+	assert((ssize_t)(kwz.len) >= 0);
+	const int cmp = kwz_between(cover_low_kwz, kwz, cover_hi_kwz);
+	if (nonexistence_ok(cmp, ans->rrsets[AR_NSEC].set.rr)) {
+		VERBOSE_MSG(qry, "=> NSEC wildcard: covered by the same RR\n");
+		return AR_SOA;
+	}
+	const knot_rrset_t *nsec_rr = NULL; /**< the wildcard proof NSEC */
+	bool exact_match; /**< whether it matches the source of synthesis */
+	if (cmp == 1) {
+		exact_match = true;
+		nsec_rr = ans->rrsets[AR_NSEC].set.rr;
+	} else {
+		/* Try to find the NSEC for SS. */
+		knot_db_val_t val = { NULL, 0 };
+		knot_db_val_t wild_low_kwz = { NULL, 0 };
+		uint32_t new_ttl;
+		const char *err = find_leq_NSEC1(cache, qry, key, k, &val,
+				&exact_match, &wild_low_kwz, NULL, &new_ttl);
+		if (err) {
+			VERBOSE_MSG(qry, "=> NSEC wildcard: %s\n", err);
+			return kr_ok();
+		}
+		/* Materialize the record into answer (speculatively). */
+		knot_dname_t owner[KNOT_DNAME_MAXLEN];
+		int ret = dname_wire_reconstruct(owner, k, wild_low_kwz);
+		if (ret) return kr_error(ret);
+		const struct entry_h *nsec_eh = val.data;
+		ret = entry2answer(ans, AR_WILD, nsec_eh, knot_db_val_bound(val),
+				   owner, KNOT_RRTYPE_NSEC, new_ttl);
+		if (ret) return kr_error(ret);
+		nsec_rr = ans->rrsets[AR_WILD].set.rr;
+	}
+
+	assert(nsec_rr);
+	const uint32_t new_ttl_log =
+		kr_verbose_status ? nsec_rr->ttl : -1;
+	const uint8_t *bm = knot_nsec_bitmap(nsec_rr->rrs.rdata);
+	uint16_t bm_size = knot_nsec_bitmap_len(nsec_rr->rrs.rdata);
+	int ret;
+	struct answer_rrset * const arw = &ans->rrsets[AR_WILD];
+	if (!bm) {
+		assert(false);
+		ret = kr_error(1);
+		goto clean_wild;
+	}
+	if (!exact_match) {
+		/* Finish verification that the source of synthesis doesn't exist. */
+		const int nsec_matched =
+			knot_dname_matched_labels(nsec_rr->owner, clencl_name);
+			/* we don't need to use the full source of synthesis ^ */
+		const bool is_sub =
+			nsec_matched == knot_dname_labels(nsec_rr->owner, NULL);
+		if (is_sub && kr_nsec_children_in_zone_check(bm, bm_size) != 0) {
+			VERBOSE_MSG(qry,
+				"=> NSEC wildcard: covered but delegated (or error)\n");
+			ret = kr_ok();
+			goto clean_wild;
+		}
+		/* We have a record proving wildcard non-existence. */
+		WITH_VERBOSE(qry) {
+			auto_free char *owner_str = kr_dname_text(nsec_rr->owner),
+				*next_str = kr_dname_text(knot_nsec_next(nsec_rr->rrs.rdata));
+			VERBOSE_MSG(qry, "=> NSEC wildcard: covered by: %s -> %s, new TTL %d\n",
+					owner_str, next_str, new_ttl_log);
+		}
+		return AR_SOA;
+	}
+
+	/* The wildcard exists.  Find if it's NODATA - check type bitmap. */
+	if (kr_nsec_bitmap_nodata_check(bm, bm_size, qry->stype, nsec_rr->owner) == 0) {
+		/* NODATA proven; just need to add SOA+RRSIG later */
+		WITH_VERBOSE(qry) {
+			const char *msg_start = "=> NSEC wildcard: match proved NODATA";
+			if (arw->set.rr) {
+				auto_free char *owner_str = kr_dname_text(nsec_rr->owner);
+				VERBOSE_MSG(qry, "%s: %s, new TTL %d\n",
+						msg_start, owner_str, new_ttl_log);
+			} else {
+				/* don't repeat the RR if it's the same */
+				VERBOSE_MSG(qry, "%s, by the same RR\n", msg_start);
+			}
+		}
+		ans->rcode = PKT_NODATA;
+		return AR_SOA;
+
+	} /* else */
+	/* The data probably exists -> don't add this NSEC
+	 * and (later) try to find the real wildcard data */
+	VERBOSE_MSG(qry, "=> NSEC wildcard: should exist (or error)\n");
+	ans->rcode = PKT_NOERROR;
+	ret = kr_ok();
+clean_wild:
+	if (arw->set.rr) { /* we may have matched AR_NSEC */
+		knot_rrset_free(arw->set.rr, ans->mm);
+		arw->set.rr = NULL;
+		knot_rdataset_clear(&arw->sig_rds, ans->mm);
+	}
+	return ret;
+}
+
diff --git a/lib/cache/nsec3.c b/lib/cache/nsec3.c
new file mode 100644
index 0000000..bebe01c
--- /dev/null
+++ b/lib/cache/nsec3.c
@@ -0,0 +1,495 @@
+/*  Copyright (C) 2018 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+/** @file
+ * Implementation of NSEC3 handling.  Prototypes in ./impl.h
+ */
+
+#include "lib/cache/impl.h"
+
+#include "contrib/base32hex.h"
+#include "lib/dnssec/nsec.h"
+#include "lib/dnssec/nsec3.h"
+#include "lib/layer/iterate.h"
+
+#include <libknot/rrtype/nsec3.h>
+
+static const knot_db_val_t VAL_EMPTY = { NULL, 0 };
+
+/** Common part: write all but the NSEC3 hash. */
+static knot_db_val_t key_NSEC3_common(struct key *k, const knot_dname_t *zname,
+					const nsec_p_hash_t nsec_p_hash)
+{
+	int ret;
+	const bool ok = k && zname
+		&& !(ret = kr_dname_lf(k->buf, zname, false));
+	if (!ok) {
+		assert(false);
+		return VAL_EMPTY;
+	}
+
+	/* CACHE_KEY_DEF: key == zone's dname_lf + '\0' + '3' + nsec_p hash (4B)
+	 * 			+ NSEC3 hash (20B == NSEC3_HASH_LEN binary!)
+	 * LATER(optim.) nsec_p hash: perhaps 2B would give a sufficient probability
+	 * of avoiding collisions.
+	 */
+	uint8_t *begin = k->buf + 1 + k->zlf_len; /* one byte after zone's zero */
+	begin[0] = 0;
+	begin[1] = '3'; /* tag for NSEC3 */
+	k->type = KNOT_RRTYPE_NSEC3;
+	memcpy(begin + 2, &nsec_p_hash, sizeof(nsec_p_hash));
+	return (knot_db_val_t){
+		.data = k->buf + 1,
+		.len = begin + 2 + sizeof(nsec_p_hash) - (k->buf + 1),
+	};
+}
+
+knot_db_val_t key_NSEC3(struct key *k, const knot_dname_t *nsec3_name,
+			const nsec_p_hash_t nsec_p_hash)
+{
+	knot_db_val_t val = key_NSEC3_common(k, nsec3_name /*only zname required*/,
+						nsec_p_hash);
+	if (!val.data) return val;
+	int len = base32hex_decode(nsec3_name + 1, nsec3_name[0],
+			knot_db_val_bound(val), KR_CACHE_KEY_MAXLEN - val.len);
+	if (len != NSEC3_HASH_LEN) {
+		return VAL_EMPTY;
+	}
+	val.len += len;
+	return val;
+}
+
+/** Construct a string key for for NSEC3 predecessor-search, from an non-NSEC3 name.
+ * \note k->zlf_len and k->zname are assumed to have been correctly set */
+static knot_db_val_t key_NSEC3_name(struct key *k, const knot_dname_t *name,
+		const bool add_wildcard, const struct nsec_p *nsec_p)
+{
+	bool ok = k && name && nsec_p && nsec_p->raw;
+	if (!ok) return VAL_EMPTY;
+	knot_db_val_t val = key_NSEC3_common(k, k->zname, nsec_p->hash);
+	if (!val.data) return val;
+
+	/* Make `name` point to correctly wildcarded owner name. */
+	uint8_t buf[KNOT_DNAME_MAXLEN];
+	int name_len;
+	if (add_wildcard) {
+		buf[0] = '\1';
+		buf[1] = '*';
+		name_len = knot_dname_to_wire(buf + 2, name, sizeof(buf) - 2);
+		if (name_len < 0) return VAL_EMPTY; /* wants wildcard but doesn't fit */
+		name = buf;
+		name_len += 2;
+	} else {
+		name_len = knot_dname_size(name);
+	}
+	/* Append the NSEC3 hash. */
+	const dnssec_binary_t dname = {
+		.size = name_len,
+		.data = (uint8_t *)/*const-cast*/name,
+	};
+
+	if (nsec_p->libknot.iterations > KR_NSEC3_MAX_ITERATIONS) {
+		/* This is mainly defensive; it shouldn't happen thanks to downgrades. */
+		assert(false);
+		return VAL_EMPTY;
+	}
+	#if 0 // LATER(optim.): this requires a patched libdnssec - tries to realloc()
+	dnssec_binary_t hash = {
+		.size = KR_CACHE_KEY_MAXLEN - val.len,
+		.data = val.data + val.len,
+	};
+	int ret = dnssec_nsec3_hash(&dname, &nsec_p->libknot, &hash);
+	if (ret != DNSSEC_EOK) return VAL_EMPTY;
+	assert(hash.size == NSEC3_HASH_LEN);
+
+	#else
+	dnssec_binary_t hash = { .size = 0, .data = NULL };
+	int ret = dnssec_nsec3_hash(&dname, &nsec_p->libknot, &hash);
+	if (ret != DNSSEC_EOK) return VAL_EMPTY;
+	if (hash.size != NSEC3_HASH_LEN || !hash.data) {
+		assert(false);
+		return VAL_EMPTY;
+	}
+	memcpy(knot_db_val_bound(val), hash.data, NSEC3_HASH_LEN);
+	free(hash.data);
+	#endif
+
+	val.len += hash.size;
+	return val;
+}
+
+/** Return h1 < h2, semantically on NSEC3 hashes. */
+static inline bool nsec3_hash_ordered(const uint8_t *h1, const uint8_t *h2)
+{
+	return memcmp(h1, h2, NSEC3_HASH_LEN) < 0;
+}
+
+/** NSEC3 range search.
+ *
+ * \param key Pass output of key_NSEC3(k, ...)
+ * \param nsec_p Restrict to this NSEC3 parameter-set.
+ * \param value[out] The raw data of the NSEC3 cache record (optional; consistency checked).
+ * \param exact_match[out] Whether the key was matched exactly or just covered (optional).
+ * \param hash_low[out] Output the low end hash of covering NSEC3, pointing within DB (optional).
+ * \param new_ttl[out] New TTL of the NSEC3 (optional).
+ * \return Error message or NULL.
+ * \note The function itself does *no* bitmap checks, e.g. RFC 6840 sec. 4.
+ */
+static const char * find_leq_NSEC3(struct kr_cache *cache, const struct kr_query *qry,
+		const knot_db_val_t key, const struct key *k, const struct nsec_p *nsec_p,
+		knot_db_val_t *value, bool *exact_match, const uint8_t **hash_low,
+		uint32_t *new_ttl)
+{
+	/* Do the cache operation. */
+	const size_t hash_off = key_nsec3_hash_off(k);
+	if (!key.data || key.len < hash_off) {
+		assert(false);
+		return "range search ERROR";
+	}
+	knot_db_val_t key_found = key;
+	knot_db_val_t val = { NULL, 0 };
+	int ret = cache_op(cache, read_leq, &key_found, &val);
+		/* ^^ LATER(optim.): incrementing key and doing less-than search
+		 * would probably be slightly more efficient with LMDB,
+		 * but the code complexity would grow considerably. */
+	if (ret < 0) {
+		if (ret == kr_error(ENOENT)) {
+			return "range search miss";
+		} else {
+			assert(false);
+			return "range search ERROR";
+		}
+	}
+	if (value) {
+		*value = val;
+	}
+	/* Check consistency, TTL, rank. */
+	const bool is_exact = (ret == 0);
+	if (exact_match) {
+		*exact_match = is_exact;
+	}
+	const struct entry_h *eh = entry_h_consistent_NSEC(val);
+	if (!eh) {
+		/* This might be just finding something else than NSEC3 entry,
+		 * in case we searched before the very first one in the zone. */
+		return "range search found inconsistent entry";
+	}
+	/* Passing just zone name instead of owner. */
+	int32_t new_ttl_ = get_new_ttl(eh, qry, k->zname, KNOT_RRTYPE_NSEC3,
+					qry->timestamp.tv_sec);
+	if (new_ttl_ < 0 || !kr_rank_test(eh->rank, KR_RANK_SECURE)) {
+		return "range search found stale or insecure entry";
+		/* TODO: remove the stale record *and* retry,
+		 * in case we haven't run off.  Perhaps start by in_zone check. */
+	}
+	if (new_ttl) {
+		*new_ttl = new_ttl_;
+	}
+	if (hash_low) {
+		*hash_low = (uint8_t *)key_found.data + hash_off;
+	}
+	if (is_exact) {
+		/* Nothing else to do. */
+		return NULL;
+	}
+	/* The NSEC3 starts strictly before our target name;
+	 * now check that it still belongs into that zone and chain. */
+	const uint8_t *nsec_p_raw = eh->data + KR_CACHE_RR_COUNT_SIZE
+					+ 2 /* RDLENGTH from rfc1034 */;
+	const int nsec_p_len = nsec_p_rdlen(nsec_p_raw);
+	const bool same_chain = key_found.len == hash_off + NSEC3_HASH_LEN
+		/* CACHE_KEY_DEF */
+		&& memcmp(key.data, key_found.data, hash_off) == 0
+		/* exact comparison of NSEC3 parameters */
+		&& nsec_p_len == nsec_p_rdlen(nsec_p->raw)
+		&& memcmp(nsec_p_raw, nsec_p->raw, nsec_p_len) == 0;
+	if (!same_chain) {
+		return "range search miss (!same_chain)";
+	}
+	/* We know it starts before sname, so let's check the other end.
+	 * A. find the next hash and check its length. */
+	if (KR_CACHE_RR_COUNT_SIZE != 2 || get_uint16(eh->data) == 0) {
+		assert(false);
+		return "ERROR";
+		/* TODO: more checks?  Also, `next` computation is kinda messy. */
+	}
+	const uint8_t *hash_next = nsec_p_raw + nsec_p_len
+				 + sizeof(uint8_t) /* hash length from rfc5155 */;
+	if (hash_next[-1] != NSEC3_HASH_LEN) {
+		return "unexpected next hash length";
+	}
+	/* B. do the actual range check. */
+	const uint8_t * const hash_searched = (uint8_t *)key.data + hash_off;
+	bool covers = /* we know for sure that the low end is before the searched name */
+		nsec3_hash_ordered(hash_searched, hash_next)
+		/* and the wrap-around case */
+		|| nsec3_hash_ordered(hash_next, (const uint8_t *)key_found.data + hash_off);
+	if (!covers) {
+		return "range search miss (!covers)";
+	}
+	return NULL;
+}
+
+/** Extract textual representation of NSEC3 hash from a cache key.
+ * \param text must have length at least NSEC3_HASH_TXT_LEN+1 (will get 0-terminated). */
+static void key_NSEC3_hash2text(const knot_db_val_t key, char *text)
+{
+	assert(key.data && key.len > NSEC3_HASH_LEN);
+	const uint8_t *hash_raw = knot_db_val_bound(key) - NSEC3_HASH_LEN;
+			/* CACHE_KEY_DEF ^^ */
+	int len = base32hex_encode(hash_raw, NSEC3_HASH_LEN, (uint8_t *)text,
+				   NSEC3_HASH_TXT_LEN);
+	assert(len == NSEC3_HASH_TXT_LEN); (void)len;
+	text[NSEC3_HASH_TXT_LEN] = '\0';
+}
+
+/** Reconstruct a name into a buffer (assuming length at least KNOT_DNAME_MAXLEN).
+ * \return kr_ok() or error code (<0). */
+static int dname_wire_reconstruct(knot_dname_t *buf, const knot_dname_t *zname,
+				  const uint8_t *hash_raw)
+{
+	int len = base32hex_encode(hash_raw, NSEC3_HASH_LEN, buf + 1, NSEC3_HASH_TXT_LEN);
+	if (len != NSEC3_HASH_TXT_LEN) {
+		assert(false);
+		return kr_error(EINVAL);
+	}
+	buf[0] = len;
+	int ret = knot_dname_to_wire(buf + 1 + len, zname, KNOT_DNAME_MAXLEN - 1 - len);
+	return ret < 0 ? kr_error(ret) : kr_ok();
+}
+
+static void nsec3_hash2text(const knot_dname_t *owner, char *text)
+{
+	assert(owner[0] == NSEC3_HASH_TXT_LEN);
+	memcpy(text, owner + 1, MIN(owner[0], NSEC3_HASH_TXT_LEN));
+	text[NSEC3_HASH_TXT_LEN] = '\0';
+}
+
+int nsec3_encloser(struct key *k, struct answer *ans,
+		   const int sname_labels, int *clencl_labels,
+		   const struct kr_query *qry, struct kr_cache *cache)
+{
+	static const int ESKIP = ABS(ENOENT);
+	/* Basic sanity check. */
+	const bool ok = k && k->zname && ans && clencl_labels
+			&& qry && cache;
+	if (!ok) {
+		assert(!EINVAL);
+		return kr_error(EINVAL);
+	}
+
+	/*** Find the closest encloser - cycle: name starting at sname,
+	 * proceeding while longer than zname, shortening by one label on step.
+	 * We need a pair where a name doesn't exist *and* its parent does. */
+		/* LATER(optim.): perhaps iterate in the other order - that
+		 * should help significantly against deep queries where we have
+		 * a shallow proof in the cache.  We can also optimize by using
+		 * only exact search unless we had a match in the previous iteration. */
+	const int zname_labels = knot_dname_labels(k->zname, NULL);
+	int last_nxproven_labels = -1;
+	const knot_dname_t *name = qry->sname;
+	for (int name_labels = sname_labels; name_labels >= zname_labels;
+					--name_labels, name += 1 + name[0]) {
+		/* Find a previous-or-equal NSEC3 in cache covering the name,
+		 * checking TTL etc. */
+		const knot_db_val_t key = key_NSEC3_name(k, name, false, &ans->nsec_p);
+		if (!key.data) continue;
+		WITH_VERBOSE(qry) {
+			char hash_txt[NSEC3_HASH_TXT_LEN + 1];
+			key_NSEC3_hash2text(key, hash_txt);
+			VERBOSE_MSG(qry, "=> NSEC3 depth %d: hash %s\n",
+					name_labels - zname_labels, hash_txt);
+		}
+		knot_db_val_t val = { NULL, 0 };
+		bool exact_match;
+		uint32_t new_ttl;
+		const uint8_t *hash_low;
+		const char *err = find_leq_NSEC3(cache, qry, key, k, &ans->nsec_p, &val,
+						 &exact_match, &hash_low, &new_ttl);
+		if (err) {
+			WITH_VERBOSE(qry) {
+				auto_free char *name_str = kr_dname_text(name);
+				VERBOSE_MSG(qry, "=> NSEC3 encloser error for %s: %s\n",
+						name_str, err);
+			}
+			continue;
+		}
+		if (exact_match && name_labels != sname_labels
+				&& name_labels + 1 != last_nxproven_labels) {
+			/* This name exists (checked rank and TTL), and it's
+			 * neither of the two interesting cases, so we do not
+			 * keep searching for non-existence above this name. */
+			VERBOSE_MSG(qry,
+				"=> NSEC3 encloser: only found existence of an ancestor\n");
+			return ESKIP;
+		}
+		/* Optimization: avoid the rest of the last iteration if pointless. */
+		if (!exact_match && name_labels == zname_labels
+		    && last_nxproven_labels != name_labels + 1) {
+			break;
+		}
+
+		/* Basic checks OK -> materialize data, cleaning any previous
+		 * records on that answer index (unsuccessful attempts). */
+		knot_dname_t owner[KNOT_DNAME_MAXLEN];
+		{
+			int ret = dname_wire_reconstruct(owner, k->zname, hash_low);
+			if (unlikely(ret)) continue;
+		}
+		const int ans_id = (exact_match && name_labels + 1 == last_nxproven_labels)
+				 ? AR_CPE : AR_NSEC;
+		{
+			const struct entry_h *nsec_eh = val.data;
+			memset(&ans->rrsets[ans_id], 0, sizeof(ans->rrsets[ans_id]));
+			int ret = entry2answer(ans, ans_id, nsec_eh, knot_db_val_bound(val),
+						owner, KNOT_RRTYPE_NSEC3, new_ttl);
+			if (ret) return kr_error(ret);
+		}
+
+		if (!exact_match) {
+			/* Non-existence proven, but we don't know if `name`
+			 * is the next closer name.
+			 * Note: we don't need to check for the sname being
+			 * delegated away by this record, as with NSEC3 only
+			 * *exact* match on an ancestor could do that. */
+			last_nxproven_labels = name_labels;
+			WITH_VERBOSE(qry) {
+				char hash_low_txt[NSEC3_HASH_TXT_LEN + 1];
+				nsec3_hash2text(owner, hash_low_txt);
+				VERBOSE_MSG(qry,
+					"=> NSEC3 depth %d: covered by %s -> TODO, new TTL %d\n",
+					name_labels - zname_labels, hash_low_txt, new_ttl);
+			}
+			continue;
+		}
+
+		/* Exactly matched NSEC3: two cases, one after another. */
+		const knot_rrset_t *nsec_rr = ans->rrsets[ans_id].set.rr;
+		const uint8_t *bm = knot_nsec3_bitmap(nsec_rr->rrs.rdata);
+		uint16_t bm_size = knot_nsec3_bitmap_len(nsec_rr->rrs.rdata);
+		assert(bm);
+		if (name_labels == sname_labels) {
+			if (kr_nsec_bitmap_nodata_check(bm, bm_size, qry->stype,
+							nsec_rr->owner) != 0) {
+				VERBOSE_MSG(qry,
+					"=> NSEC3 sname: match but failed type check\n");
+				return ESKIP;
+			}
+			/* NODATA proven; just need to add SOA+RRSIG later */
+			VERBOSE_MSG(qry,
+				"=> NSEC3 sname: match proved NODATA, new TTL %d\n",
+				new_ttl);
+			ans->rcode = PKT_NODATA;
+			return kr_ok();
+
+		} /* else */
+
+		assert(name_labels + 1 == last_nxproven_labels);
+		if (kr_nsec_children_in_zone_check(bm, bm_size) != 0) {
+			VERBOSE_MSG(qry,
+				"=> NSEC3 encloser: found but delegated (or error)\n");
+			return ESKIP;
+		}
+		/* NXDOMAIN proven *except* for wildcards. */
+		WITH_VERBOSE(qry) {
+			auto_free char *name_str = kr_dname_text(name);
+			VERBOSE_MSG(qry,
+				"=> NSEC3 encloser: confirmed as %s, new TTL %d\n",
+				name_str, new_ttl);
+		}
+		*clencl_labels = name_labels;
+		ans->rcode = PKT_NXDOMAIN;
+		/* Avoid repeated NSEC3 - remove either if the hashes match.
+		 * This is very unlikely in larger zones: 1/size (per attempt).
+		 * Well, deduplication would happen anyway when the answer
+		 * from cache is read by kresd (internally). */
+		if (unlikely(0 == memcmp(ans->rrsets[AR_NSEC].set.rr->owner + 1,
+					 ans->rrsets[AR_CPE ].set.rr->owner + 1,
+					 NSEC3_HASH_LEN))) {
+			memset(&ans->rrsets[AR_CPE], 0, sizeof(ans->rrsets[AR_CPE]));
+			/* LATER(optim.): perhaps check this earlier and avoid some work? */
+		}
+		return kr_ok();
+	}
+
+	/* We've ran out of options. */
+	if (last_nxproven_labels > 0) {
+		/* We didn't manage to prove existence of the closest encloser,
+		 * meaning the only chance left is a *positive* wildcard record. */
+		*clencl_labels = last_nxproven_labels - 1;
+		ans->rcode = PKT_NXDOMAIN;
+		/* FIXME: review */
+	}
+	return ESKIP;
+}
+
+int nsec3_src_synth(struct key *k, struct answer *ans, const knot_dname_t *clencl_name,
+		    const struct kr_query *qry, struct kr_cache *cache)
+{
+	/* Find a previous-or-equal NSEC3 in cache covering or matching
+	 * the source of synthesis, checking TTL etc. */
+	const knot_db_val_t key = key_NSEC3_name(k, clencl_name, true, &ans->nsec_p);
+	if (!key.data) return kr_error(1);
+	WITH_VERBOSE(qry) {
+		char hash_txt[NSEC3_HASH_TXT_LEN + 1];
+		key_NSEC3_hash2text(key, hash_txt);
+		VERBOSE_MSG(qry, "=> NSEC3 wildcard: hash %s\n", hash_txt);
+	}
+	knot_db_val_t val = { NULL, 0 };
+	bool exact_match;
+	uint32_t new_ttl;
+	const uint8_t *hash_low;
+	const char *err = find_leq_NSEC3(cache, qry, key, k, &ans->nsec_p, &val,
+					 &exact_match, &hash_low, &new_ttl);
+	if (err) {
+		VERBOSE_MSG(qry, "=> NSEC3 wildcard: %s\n", err);
+		return kr_ok();
+	}
+
+	/* LATER(optim.): avoid duplicities in answer. */
+
+	/* Basic checks OK -> materialize the data (speculatively). */
+	knot_dname_t owner[KNOT_DNAME_MAXLEN];
+	{
+		int ret = dname_wire_reconstruct(owner, k->zname, hash_low);
+		if (unlikely(ret)) return kr_ok();
+		const struct entry_h *nsec_eh = val.data;
+		ret = entry2answer(ans, AR_WILD, nsec_eh, knot_db_val_bound(val),
+				   owner, KNOT_RRTYPE_NSEC3, new_ttl);
+		if (ret) return kr_error(ret);
+	}
+	const knot_rrset_t *nsec_rr = ans->rrsets[AR_WILD].set.rr;
+
+	if (!exact_match) {
+		/* The record proves wildcard non-existence. */
+		WITH_VERBOSE(qry) {
+			char hash_low_txt[NSEC3_HASH_TXT_LEN + 1];
+			nsec3_hash2text(owner, hash_low_txt);
+			VERBOSE_MSG(qry,
+				"=> NSEC3 wildcard: covered by %s -> TODO, new TTL %d\n",
+				hash_low_txt, new_ttl);
+		}
+		return AR_SOA;
+	}
+
+	/* The wildcard exists.  Find if it's NODATA - check type bitmap. */
+	const uint8_t *bm = knot_nsec3_bitmap(nsec_rr->rrs.rdata);
+	uint16_t bm_size = knot_nsec3_bitmap_len(nsec_rr->rrs.rdata);
+	assert(bm);
+	if (kr_nsec_bitmap_nodata_check(bm, bm_size, qry->stype, nsec_rr->owner) == 0) {
+		/* NODATA proven; just need to add SOA+RRSIG later */
+		VERBOSE_MSG(qry, "=> NSEC3 wildcard: match proved NODATA, new TTL %d\n",
+				 new_ttl);
+		ans->rcode = PKT_NODATA;
+		return AR_SOA;
+
+	} /* else */
+	/* The data probably exists -> don't add this NSEC3
+	 * and (later) try to find the real wildcard data */
+	VERBOSE_MSG(qry, "=> NSEC3 wildcard: should exist (or error)\n");
+	ans->rcode = PKT_NOERROR;
+	memset(&ans->rrsets[AR_WILD], 0, sizeof(ans->rrsets[AR_WILD]));
+	return kr_ok();
+}
+
diff --git a/lib/cache/overflow.test.integr/deckard.yaml b/lib/cache/overflow.test.integr/deckard.yaml
new file mode 100644
index 0000000..61032fb
--- /dev/null
+++ b/lib/cache/overflow.test.integr/deckard.yaml
@@ -0,0 +1,22 @@
+# SPDX-License-Identifier: GPL-3.0-or-later
+programs:
+- name: kresd1
+  binary: kresd
+  additional:
+    - -n
+  templates:
+    - lib/cache/overflow.test.integr/kresd_config.j2
+    - tests/config/test_dns_generators.lua
+  configs:
+    - config
+    - dns_gen.lua
+- name: kresd2
+  binary: kresd
+  additional:
+    - -n
+  templates:
+    - lib/cache/overflow.test.integr/kresd_config.j2
+    - tests/config/test_dns_generators.lua
+  configs:
+    - config
+    - dns_gen.lua
diff --git a/lib/cache/overflow.test.integr/kresd_config.j2 b/lib/cache/overflow.test.integr/kresd_config.j2
new file mode 100644
index 0000000..87dbd69
--- /dev/null
+++ b/lib/cache/overflow.test.integr/kresd_config.j2
@@ -0,0 +1,91 @@
+-- SPDX-License-Identifier: GPL-3.0-or-later
+
+trust_anchors.remove('.')
+{% for TAF in TRUST_ANCHOR_FILES %}
+trust_anchors.add_file('{{TAF}}')
+{% endfor %}
+
+modules.load("hints")
+hints.root({['{{ROOT_NAME}}'] = '{{ROOT_ADDR}}'})
+
+{% raw %}
+-- Disable RFC5011 TA update
+if ta_update then
+        modules.unload('ta_update')
+end
+
+-- Disable RFC8145 signaling, scenario doesn't provide expected answers
+if ta_signal_query then
+        modules.unload('ta_signal_query')
+end
+
+-- Disable RFC8109 priming, scenario doesn't provide expected answers
+if priming then
+        modules.unload('priming')
+end
+
+-- Disable this module because it make one priming query
+if detect_time_skew then
+        modules.unload('detect_time_skew')
+end
+
+verbose(true)
+policy.add(policy.all(policy.DEBUG_ALWAYS))
+
+cache.open(1*MB)
+
+{% endraw %}
+
+{% if DO_IP6 == "true" %}
+net.ipv6 = true
+{% else %}
+net.ipv6 = false
+{% endif %}
+
+{% if DO_IP4 == "true" %}
+net.ipv4 = true
+{% else %}
+net.ipv4 = false
+{% endif %}
+
+-- both instances listen on both addresses
+-- so queries get distributed between them randomly
+net.listen('{{programs[0]["address"]}}')
+net.listen('{{programs[1]["address"]}}')
+
+{% raw %}
+-- Self-checks on globals
+assert(help() ~= nil)
+assert(worker.id ~= nil)
+-- Self-checks on facilities
+assert(cache.stats() ~= nil)
+assert(cache.backends() ~= nil)
+assert(worker.stats() ~= nil)
+assert(net.interfaces() ~= nil)
+-- Self-checks on loaded stuff
+{% endraw %}
+
+assert(net.list()[1].transport.ip == '{{programs[0]["address"]}}')
+
+{% raw %}
+assert(#modules.list() > 0)
+-- Self-check timers
+ev = event.recurrent(1 * sec, function (ev) return 1 end)
+event.cancel(ev)
+ev = event.after(0, function (ev) return 1 end)
+
+local ffi = require('ffi')
+local kr_cach = kres.context().cache
+
+-- canary for cache overflow
+local kr_rrset = kres.rrset(
+	todname('www.example.com'),
+	kres.type.A,
+	kres.class.IN,
+	604800)
+assert(kr_rrset:add_rdata('\192\000\002\001', 4))
+assert(kr_cach:insert(kr_rrset, nil, ffi.C.KR_RANK_SECURE))
+
+local generators = dofile('./dns_gen.lua')
+event.after(0, generators.gen_batch)
+{% endraw %}
diff --git a/lib/cache/overflow.test.integr/world_cz_vutbr_www.rpl b/lib/cache/overflow.test.integr/world_cz_vutbr_www.rpl
new file mode 100644
index 0000000..eddfbd0
--- /dev/null
+++ b/lib/cache/overflow.test.integr/world_cz_vutbr_www.rpl
@@ -0,0 +1,298 @@
+do-ip4: no
+
+; test with real world Internet data
+; attempt to resolve www.vutbr.cz. A leads to CNAME piranha.ro.vutbr.cz.
+; sub-trees vutbr.cz and ro.vutbr.cz. are in separate zones
+; hosted on the same servers with different DNSKEYs
+
+val-override-date: 20170124180319
+trust-anchor: ".	172800	IN	DS	19036 8 2 49aac11d7b6f6446702e54a1607371607a1a41855200fd2ce1cdde32f24e8fb5"
+stub-addr: 2001:dc3::35
+CONFIG_END
+
+SCENARIO_BEGIN www.vutbr.cz. CNAME kresd issue #130
+
+; DNS root ; M.ROOT-SERVERS.NET.
+RANGE_BEGIN 0 100
+	ADDRESS 2001:dc3::35
+
+ENTRY_BEGIN
+MATCH opcode qtype qname
+ADJUST copy_id
+REPLY QR AA DO NOERROR
+SECTION QUESTION
+.		IN	DNSKEY
+SECTION ANSWER
+.	16567	IN	DNSKEY	257 3 8 AwEAAagAIKlVZrpC6Ia7gEzahOR+9W29euxhJhVVLOyQbSEW0O8gcCjF FVQUTf6v58fLjwBd0YI0EzrAcQqBGCzh/RStIoO8g0NfnfL2MTJRkxoX bfDaUeVPQuYEhg37NZWAJQ9VnMVDxP/VHL496M/QZxkjf5/Efucp2gaD X6RS6CXpoY68LsvPVjR0ZSwzz1apAzvN9dlzEheX7ICJBBtuA6G3LQpz W5hOA2hzCTMjJPJ8LbqF6dsV6DoBQzgul0sGIcGOYl7OyQdXfZ57relS Qageu+ipAdTTJ25AsRTAoub8ONGcLmqrAmRLKBP1dfwhYB4N7knNnulq QxA+Uk1ihz0=
+.	16567	IN	DNSKEY	256 3 8 AwEAAYvgWbYkpeGgdPKaKTJU3Us4YSTRgy7+dzvfArIhi2tKoZ/WR1Df w883SOU6Uw7tpVRkLarN0oIMK/xbOBD1DcXnyfElBwKsz4sVVWmfyr/x +igD/UjrcJ5zEBUrUmVtHyjar7ccaVc1/3ntkhZjI1hcungAlOhPhHlk MeX+5Azx6GdX//An5OgrdyH3o/JmOPMDX1mt806JI/hf0EwAp1pBwo5e 8SrSuR1tD3sgNjr6IzCdrKSgqi92z49zcdis3EaY199WFW60DCS7ydu+ +T5Xa+GyOw1quagwf/JUC/mEpeBQYWrnpkBbpDB3sy4+P2i8iCvavehb RyVm9U0MlIc=
+.	16567	IN	RRSIG	DNSKEY 8 0 172800 20170201000000 20170111000000 19036 . Sh+EpofvZgk3J9szMD2B94FxFgyIUKz3hkbCjgWSTqPQyhqNgqVU8QlS EtOo8YLmS4AX98eit5Gmmb2ObpkGoXBmAzu5w/Qt5WsGsWzLQhYrsy9s lDmFQ2JKUoCyfdwqhlJ8VxjzdFdMUiVl+/GPnv4yjxjM8Ke3VAtBkn6n BO7JkcxxOfcgZdZ4MuvSr40K/SenZE+JlLLL1LF4TMCGqaZTTdOx6kFF KSSgy2AS884htWcK0tnwRc630g6nAI2wdvjlRLBeisbfXanI4v8iiPyT FnMmnV7wJGWJ4gtRJ0UH3u5RWXUPZ+s1tKytk3slXbLyQ9xkEDveuD+h b659gQ==
+ENTRY_END
+
+ENTRY_BEGIN
+MATCH opcode subdomain
+ADJUST copy_id copy_query
+REPLY QR DO NOERROR
+SECTION QUESTION
+cz.		IN	NS
+SECTION AUTHORITY
+cz.	172800	IN	NS	d.ns.nic.cz.
+cz.	172800	IN	NS	a.ns.nic.cz.
+cz.	172800	IN	NS	c.ns.nic.cz.
+cz.	172800	IN	NS	b.ns.nic.cz.
+cz.	86400	IN	DS	54576 10 2 397E50C85EDE9CDE33F363A9E66FD1B216D788F8DD438A57A423A386 869C8F06
+cz.	86400	IN	RRSIG	DS 8 1 86400 20170202170000 20170120160000 61045 . ig2BBmA1kOuTqhVogqLciH40Ina7BCrG/fcaNARSWoaFHGOcC/7KsBZO uMttn/hKDJkH3RPsed2Oswl9bXZ+zrhjeXluUqC0zmsUJDBkS+AkiFJL HCpMSIZaXu/w1ZMADGfyQXl7XWCRbl+eyXi2eTG0SdLtRHNhm3CGJP3C xjzVuOTr9oPEyL0U81jhhlJPCFe8xDD441wLLzpEuVX8VP9N2S1QnIjO BhCEE9OTkPgpS7fMPEl0Yq2gfpRl+DCw1Dd0VB3Hh5M3hmrXuFqNYZQK b0JqDFGYhzvcpUs3EiB9IG7rJt51n6pxCTek1M2w+s6mLYzawVfq+b1Q uQD98A==
+SECTION ADDITIONAL
+a.ns.nic.cz.	172800	IN	A	194.0.12.1
+b.ns.nic.cz.	172800	IN	A	194.0.13.1
+c.ns.nic.cz.	172800	IN	A	194.0.14.1
+d.ns.nic.cz.	172800	IN	A	193.29.206.1
+a.ns.nic.cz.	172800	IN	AAAA	2001:678:f::1
+b.ns.nic.cz.	172800	IN	AAAA	2001:678:10::1
+c.ns.nic.cz.	172800	IN	AAAA	2001:678:11::1
+d.ns.nic.cz.	172800	IN	AAAA	2001:678:1::1
+ENTRY_END
+; end of M.ROOT-SERVERS.NET.
+RANGE_END
+
+
+; domains: cz. ; ?.ns.nic.cz.
+RANGE_BEGIN 0 100
+	ADDRESS 194.0.12.1
+	ADDRESS 194.0.13.1
+	ADDRESS 194.0.14.1
+	ADDRESS 193.29.206.1
+	ADDRESS 2001:678:f::1
+	ADDRESS 2001:678:10::1
+	ADDRESS 2001:678:11::1
+	ADDRESS 2001:678:1::1
+
+
+ENTRY_BEGIN
+MATCH opcode qtype qname
+ADJUST copy_id
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+cz.		IN	DNSKEY
+SECTION ANSWER
+cz.	18000	IN	DNSKEY	256 3 10 AwEAAc9e2YFnG56xtTXu42GLGAkwsrFOBBwOZphNat7HQdBmfi0CbmDf oywCUsaSkObNmm+Zu9MYLNJDHsD+vxsZbtHClpYaSEhMEmHrbnj0BMPV A6hwY6YDGFhKudJ62RmB/rmhQ3iwmICsEdRn2w5fu1rHZv8UJOUMkeWd 6GA48mW3
+cz.	18000	IN	DNSKEY	256 3 10 AwEAAdWL2Br92Vx0dLEOOB8y02ss8LtKIyGlLJ2ymJ02WqR3AAEEZN0f NPKF77kdKsjlG8DlzmSIOR12aa9EhpXqyHOwWI0kHOMJVnn6ZKFIAl71 JP/dYIcshYUxKZZMe+zEAUrVtzlLVDtM6cDOPDuBNa1ujYec3eJl9Ipq eUEG6gAH
+cz.	18000	IN	DNSKEY	257 3 10 AwEAAay0hi4HN2r/BqMQTpIPIVDyjmyF+9ZWvr5Lewx+q+947o/GrRv4 FGFfkZxf9CFfYVUf0jG5Yq4i06pGVNwJl81HS9Ux2oeHRXUvgtLnl5He RVLL+zgI5byx9HSNr4bPO8ZEn5OjoayhkNyGSFr4VWrzQk/K02vLP4d1 cCEzUQy30eyZto2/tG5ZwCU/iRkS1PJOcOW98hiFIfFDZv1XjbEpqEYh T2PATs6rt+BKwSHKGISmg1PNdg+y0rItemYMWr1f9BGAdtTWoPCPCYPj OZMPoIyA4tMscD+ww54Jf/QNoHccY4hO1yHiuAXG7SUn8jo0IKQ9W7JJ xES0aqFCX/0=
+cz.	18000	IN	RRSIG	DNSKEY 10 1 18000 20170127000000 20170120000000 54576 cz. Fdl//hMdLoZq8//gLt/+3a7LfWqB5/psW9YR3AWNPQGfvrEAcKRBcah+ ikbSCmpAZ6j834xZP1zPd5xMoN33PGXf23iqcgjHvUn50Uq48KRBVYwU H885xNJBl/Po0N8STeG0WNZz2mbUbBbPCGN7CI5yl08usvqOvf2fV8+D 0m//+Fa1cWaqMXpHc6OnhWZ+BN4VdcxxwNbGhH2TZxyiGEMMscEGoIxn yL1pVY8T93LOMwQmuFJ71f8Scij3vYouW/mNuEma/UUZM1bEn8vR1UrP /6JTGPGTG+snHvCxiVtAxCNnqoIJDD+xuonpZLeKN5XU7UDMZPDTtSgX vtzjww==
+cz.	18000	IN	RRSIG	DNSKEY 10 1 18000 20170205002523 20170123080953 58211 cz. MZ6KTtQisTde4iOBH6oasl7bVrRM5ly7Yxdv2l+2gk1YYk4zX6L3m6oB P26SKi+fj8pM77775bRK7uCI9FlyqXa3MJclLU/GmnRANm6T4sSdz0zs F3FK4UfUmHnzdnWXWTnueDfIZr44yF1y1+4I3E96/9/nEYGO+xsifvIj iks=
+ENTRY_END
+
+ENTRY_BEGIN
+MATCH opcode subdomain
+ADJUST copy_id copy_query
+REPLY QR DO NOERROR
+SECTION QUESTION
+vutbr.cz.			IN	NS
+SECTION AUTHORITY
+vutbr.cz.		18000	IN	NS	pipit.cis.vutbr.cz.
+vutbr.cz.		18000	IN	NS	rhino.cis.vutbr.cz.
+vutbr.cz.		18000	IN	DS	5512 5 2 78510F9433A4D536A5B9099193E9D58EE5B5CF71F14D983B4DA2EB16 29CFA1E9
+vutbr.cz.		18000	IN	RRSIG	DS 10 2 18000 20170204213601 20170123080953 58211 cz. lXNBswz/r/1NY7VQq+BlisC+1yqFmUBIaF30L8XDAbiHLcj/AIj0dEy6 PlBlkEeDAi4W9DvR0jo9LjHvFFJLs54cuEEd3pHTdlw8x0dLd1X7Zkh7 cezfAt2EEqdux/ce/sc86lUKOpLnDtry2piWwVf2EqFg9NlW4cHTm78U gsY=
+SECTION ADDITIONAL
+pipit.cis.vutbr.cz.	18000	IN	A	77.93.219.110
+rhino.cis.vutbr.cz.	18000	IN	A	147.229.3.10
+pipit.cis.vutbr.cz.	18000	IN	AAAA	2a01:430:120::4d5d:db6e
+rhino.cis.vutbr.cz.	18000	IN	AAAA	2001:67c:1220:e000::93e5:30a
+ENTRY_END
+
+; end of domain cz.: servers ?.ns.nic.cz.
+RANGE_END
+
+
+; domains: vutbr.cz. + ro.vutbr.cz.
+; servers: pipit.cis.vutbr.cz. + rhino.cis.vutbr.cz. + shark.ro.vutbr.cz.
+; shark.ro.vutbr.cz. in fact serves both domains but is listed only in ro.vutbr.cz NS
+RANGE_BEGIN 0 100
+	ADDRESS 77.93.219.110
+	ADDRESS 147.229.3.10
+	ADDRESS 147.229.2.59
+	ADDRESS 2a01:430:120::4d5d:db6e
+	ADDRESS 2001:67c:1220:e000::93e5:30a
+
+ENTRY_BEGIN
+MATCH opcode qtype qname
+ADJUST copy_id
+REPLY QR AA DO
+SECTION QUESTION
+vutbr.cz.		IN	NS
+SECTION ANSWER
+vutbr.cz.		28800	IN	NS	rhino.cis.vutbr.cz.
+vutbr.cz.		28800	IN	NS	pipit.cis.vutbr.cz.
+vutbr.cz.		28800	IN	RRSIG	NS 5 2 28800 20170216060902 20170117060902 39756 vutbr.cz. y6Jj5vfvdlLeecB/++/qyhjCzfnFJyY1sX1Ja+wV0ulq3laeCVV7ICXh PKG+CjHUu/nDOrzT9QJP4qxYDCANneI0yxI82XKhhoTN5O/TxyWH/DyT k8JarRoMooHv2RwKd8jtLIxvj1SaJ+AvlP0pOPraaVgbHtn1SJ4ubxQD cFc=
+SECTION ADDITIONAL
+pipit.cis.vutbr.cz.	86400	IN	A	77.93.219.110
+pipit.cis.vutbr.cz.	86400	IN	AAAA	2a01:430:120::4d5d:db6e
+rhino.cis.vutbr.cz.	86400	IN	A	147.229.3.10
+rhino.cis.vutbr.cz.	86400	IN	AAAA	2001:67c:1220:e000::93e5:30a
+pipit.cis.vutbr.cz.	86400	IN	RRSIG	A 5 4 86400 20170204080646 20170105080646 28257 cis.vutbr.cz. Cz9etHnEOQTzu+6rYJEqx/SQ1tQgPOCyf8HSj4KOsx89jtgiHNC6pep6 ZE0SphMGAs3jC/uGIhlaFNZ3i38OQIMuqwacbz+XZyW5bByvV3QZrhqh dFxMDfmPuNiCAT3crFpUkvVW1OE3YfGHzZGXX7JP5wb1b8A3X6Qih7fV +nQ=
+pipit.cis.vutbr.cz.	86400	IN	RRSIG	AAAA 5 4 86400 20170204080646 20170105080646 28257 cis.vutbr.cz. piafjh6my2fooZRrzwCu9RQ95gYaMQkhIkDaGX/fT6wXzSdmgFZkS1Nl EMIKdDCQaPrLGMG3p32ptMkAm4esPekeyNtLSMBtXwZyUkgEGn6h1QM2 Yr3TOo8cixfk5nmRRdlYadf5krLb8yI9exiqeymgEQLa1YNRz/bWArlX bn8=
+rhino.cis.vutbr.cz.	86400	IN	RRSIG	A 5 4 86400 20170204080646 20170105080646 28257 cis.vutbr.cz. X/tDf8e3JEV0LxiItfpQnBzeaRIq693VG8d30iCH4/1I0uqyCfxboWmm /CBpn9A8MCJu9NEEv+4+povNlfUfqi2yjsqJEVj8ztHxD4g9cc284Cv6 ySjxrSZ9axVqoaopEXujiTwwWJUFcgF6pxqyXVksW7sgKJrboM4VSlQD +Sw=
+rhino.cis.vutbr.cz.	86400	IN	RRSIG	AAAA 5 4 86400 20170204080646 20170105080646 28257 cis.vutbr.cz. T3Yf5PAkSeJtoOH90ea9zZBG9FC3iFhiCSerDn6d9up8GRfzxDsavYJC zQu+3vnOySySn+3TMzQSSFcWdJC2iO7ulaDGr177Gof9QJbKSVSMW7jt YDE2f4/R4Go3NZVwjk/HfpCInoR6pHNA1s/9hMnWtiVopmBdfzyd3/sW YOU=
+ENTRY_END
+
+ENTRY_BEGIN
+MATCH opcode qtype qname
+ADJUST copy_id
+REPLY QR AA DO
+SECTION QUESTION
+vutbr.cz.		IN	DNSKEY
+SECTION ANSWER
+vutbr.cz.	28800	IN	DNSKEY	256 3 5 AwEAAfwRRuGjpt9v4fzuIWFA9MtGfxDrIKhoFA7DNq6B+iCOoQb6t0HZ I9lGDUSR5DRswDGP569NJ/uVD4tJxGnaK2SBQVxIu+bEP1Ouzk+O43iO 8odw50NBWetljjNDP32B3zHpgJRpxyEqzDQaQ6B4Zer6sDZm9wo5SVJe r9LjJV9p
+vutbr.cz.	28800	IN	DNSKEY	257 3 5 AwEAAfhR+s/4SLZZNA+kD2u1UgYBUu+X3Avi60QCaE1o2STterM405s8 mWMWJOlZGtjjIky3TEMxQ0+ZtMbEeJu2wNDLdV/XglX+pJAjyy728WJH 4u2/gJR8ZWsEIc0Jwb4FjwmBiF2Koz0SGVvrzEZ9T1H7dHq2X6f8KzYB otJyrAIWr9tZi/9tHrngZJ5wXELmMPWCfEFapdQMoKWoNvzrMYFli17R Mz7gJzCmNxMRV8/WkjsNPgYsTKpsAT8qEsXiTN9987AIKPHvc5j+/njq +fTXdOqGVpIgSiso+qJMddEMBcu/MBBYVFOwRQe1ez2tMwIX7y5mwDvK 0wsmyRvHugfFuxSnfiJvQr05kSnj0wxD9s9LNhrF4PocrcYqnBN/lBx9 D6633jJ3zT3T5Foe/Vj9A/X7F2oN6FOkdwO+YSEUot980pJQut6DR22U P4bLakyDMiTdOQ31c/dRIoTsccxw+838pXFyEPgiqOHRSeN/w9km6BID cl+32Xq97kXSMQH6AxOUsx9/Mxdj7ISwbS4utaAWoP460+TMcnfJfWfB NEWhuFvnfB9l63ZjZToB2PUVhrTxRwKUlfMLegSJKoZfiae82kK1pN4x FYyquKSykm/oXsM2w4OQvpqGcTwAXzZ5s95J45f7PsCap0bscGKumxsH cDswWpUz/UVosIrr
+vutbr.cz.	28800	IN	RRSIG	DNSKEY 5 2 28800 20170216060902 20170117060902 5512 vutbr.cz. QHw07MAjA4NFi3On8zaMw/q4IuADXVp4TODfK5PHb8OUIX2Yy+bKLrSX /Cc9ClWUpE69x80F9dFEeRZGJiYOwstNQGQVeq/EKNytm1XmhS8cp3SW CYHBpLjZGPrlhvqPhWd0S4vqPNiD8hDzgFAgaCNfwXDDKXhF2/qtpQ0V pDnytMP6pNPLPMpF2hzaLfCMzABShxcEOAr7+KTbxbffOik4YneG8seu XDtBvCVjP8lJcSU+q+UbotLnjyOgn8vV8pliTNqcvRsJTdtvTlJKHu8B iLkFeCE1DpRhyrVT5zC9NSOcoIv7tau2NE2oUPgtRzK76el6i9L9LcSs G+59j02AINefpAtc6W2khmTnGthibeOy/F9FuFkXUy6AmqIdNszMAj++ 8Mzv3A1OHfsfpIS3tLmC4drhdSHr2ab0Pe0lYQq2a9FSeQzSk6s9gwwZ gMVPVQHbouyvn6BCHaRVDjTV8GPKlk3C8GNaHcHb1hAGSPpw3kqL41dd K92Un4tLIoOYomxUYoyMtyxxwddXyR7ivToUHF7e/yv8MACMEo72N9sf y4zLEqkL1mJ1pCp3csI1bKaaA/c7sqb7PX93iqvoY06k55Pd7kT+lAF1 7QvXGg4U1kDrwytQPyocN8wmsX3//CpWUD07v8fCUqKOcIrVNGnoPmPC PpNe3AtpJoE=
+vutbr.cz.	28800	IN	RRSIG	DNSKEY 5 2 28800 20170216060902 20170117060902 39756 vutbr.cz. CNDE7Ht7xm8Jo9tuOlJ8N9+vI/Htfpk53MI0HG7B1EZJws/yEV7YFOOL SIAt3rzu1OHjaxr4CG/baqGRPtsaWSBHuLSdSduivxXw8xiQcMKzP6Cz 7xhJkQZxzDJ4oO5L2K2zWHcAJ8lfP1/3NHHoH1p2RATLN5sI7ofQE//W +ck=
+ENTRY_END
+
+ENTRY_BEGIN
+MATCH opcode qtype qname
+ADJUST copy_id
+REPLY QR AA DO
+SECTION QUESTION
+www.vutbr.cz.			IN	A
+SECTION ANSWER
+www.vutbr.cz.		300	IN	CNAME	piranha.ro.vutbr.cz.
+www.vutbr.cz.		300	IN	RRSIG	CNAME 5 3 300 20170216060902 20170117060902 39756 vutbr.cz. 9B3UC5SOEw1+yKlYlOTINEuNq0Kdglywc5IYJwzeSzQ3ykptzZo3ABSy bYhTqImVkhm/4NFM9/4HWMHPDzTmrWS0mCI/ljCd/oe/PxW/uESvo4P5 EQzlcuH6xBzc1KdEFAJOSmRzFjj3vyK1QN3k/c+1y2oMFOYOR2oOzCw+ MIE=
+piranha.ro.vutbr.cz.	3600	IN	A	147.229.2.90
+piranha.ro.vutbr.cz.	3600	IN	RRSIG	A 5 4 3600 20170222120032 20170123120032 12150 ro.vutbr.cz. Jz8bcAADQjCKTCcF70IK1aHGQlM4ukyN0myABlxoPaqid1mHX5jwR91b kdQmUAh2xDitlgRLbFjbUUgmjSPzQ5Qt7GAFUsVmqxvjbOLZjqHER1dh zmiWO0fDvvP647Osv3RiAP822rNUJcJrUBZU9LmeP05gwIHcpJrhdVBT b7I=
+SECTION AUTHORITY
+ro.vutbr.cz.		86400	IN	NS	shark.ro.vutbr.cz.
+ro.vutbr.cz.		86400	IN	NS	rhino.cis.vutbr.cz.
+ro.vutbr.cz.		86400	IN	NS	pipit.cis.vutbr.cz.
+ro.vutbr.cz.		86400	IN	RRSIG	NS 5 3 86400 20170222120032 20170123120032 12150 ro.vutbr.cz. HAQ8A+QNsS1WIXdW/fbT3jP+IxObBBvgUmvzsmJBXo8HMtnMAcuCQGmB 2JBQsQethQXsdyLnMK8to/5A9VRkqkAa7edxUoy7SdDi/mzGeLAVhF+5 kXSPD6t1vjiNdnIYAMpiOQbodCGxAnq6jnNyrjEzffdq3qw+5IkFNdG4 7Pw=
+SECTION ADDITIONAL
+rhino.cis.vutbr.cz.	83217	IN	A	147.229.3.10
+rhino.cis.vutbr.cz.	83217	IN	AAAA	2001:67c:1220:e000::93e5:30a
+shark.ro.vutbr.cz.	3600	IN	A	147.229.2.59
+pipit.cis.vutbr.cz.	14794	IN	A	77.93.219.110
+pipit.cis.vutbr.cz.	14794	IN	AAAA	2a01:430:120::4d5d:db6e
+rhino.cis.vutbr.cz.	83217	IN	RRSIG	A 5 4 86400 20170204080646 20170105080646 28257 cis.vutbr.cz. X/tDf8e3JEV0LxiItfpQnBzeaRIq693VG8d30iCH4/1I0uqyCfxboWmm /CBpn9A8MCJu9NEEv+4+povNlfUfqi2yjsqJEVj8ztHxD4g9cc284Cv6 ySjxrSZ9axVqoaopEXujiTwwWJUFcgF6pxqyXVksW7sgKJrboM4VSlQD +Sw=
+rhino.cis.vutbr.cz.	83217	IN	RRSIG	AAAA 5 4 86400 20170204080646 20170105080646 28257 cis.vutbr.cz. T3Yf5PAkSeJtoOH90ea9zZBG9FC3iFhiCSerDn6d9up8GRfzxDsavYJC zQu+3vnOySySn+3TMzQSSFcWdJC2iO7ulaDGr177Gof9QJbKSVSMW7jt YDE2f4/R4Go3NZVwjk/HfpCInoR6pHNA1s/9hMnWtiVopmBdfzyd3/sW YOU=
+shark.ro.vutbr.cz.	3600	IN	RRSIG	A 5 4 3600 20170222120032 20170123120032 12150 ro.vutbr.cz. SmhgyF48yX/6yH7AdSmGX60NL/xaiKH/oAzB0rnPfQZ6j+UfV57ginVV lj798K9A8jjucUpqE8ua2mZ6/aOhpqlV2iI0CZXG44zOupsCY1/OXBDx YNetBcjoXDQCBQRLLLEUL5FerDVxqT74ngdLdKubwRdrB0TLQlvpBr+F Tc8=
+pipit.cis.vutbr.cz.	85923	IN	RRSIG	A 5 4 86400 20170204080646 20170105080646 28257 cis.vutbr.cz. Cz9etHnEOQTzu+6rYJEqx/SQ1tQgPOCyf8HSj4KOsx89jtgiHNC6pep6 ZE0SphMGAs3jC/uGIhlaFNZ3i38OQIMuqwacbz+XZyW5bByvV3QZrhqh dFxMDfmPuNiCAT3crFpUkvVW1OE3YfGHzZGXX7JP5wb1b8A3X6Qih7fV +nQ=
+pipit.cis.vutbr.cz.	85923	IN	RRSIG	AAAA 5 4 86400 20170204080646 20170105080646 28257 cis.vutbr.cz. piafjh6my2fooZRrzwCu9RQ95gYaMQkhIkDaGX/fT6wXzSdmgFZkS1Nl EMIKdDCQaPrLGMG3p32ptMkAm4esPekeyNtLSMBtXwZyUkgEGn6h1QM2 Yr3TOo8cixfk5nmRRdlYadf5krLb8yI9exiqeymgEQLa1YNRz/bWArlX bn8=
+ENTRY_END
+
+ENTRY_BEGIN
+MATCH opcode qtype qname
+ADJUST copy_id
+REPLY QR AA DO
+SECTION QUESTION
+ro.vutbr.cz.       		IN      NS
+SECTION ANSWER
+ro.vutbr.cz.		86400	IN	NS	pipit.cis.vutbr.cz.
+ro.vutbr.cz.		86400	IN	NS	rhino.cis.vutbr.cz.
+ro.vutbr.cz.		86400	IN	NS	shark.ro.vutbr.cz.
+ro.vutbr.cz.		86400	IN	RRSIG	NS 5 3 86400 20170222120032 20170123120032 12150 ro.vutbr.cz. HAQ8A+QNsS1WIXdW/fbT3jP+IxObBBvgUmvzsmJBXo8HMtnMAcuCQGmB 2JBQsQethQXsdyLnMK8to/5A9VRkqkAa7edxUoy7SdDi/mzGeLAVhF+5 kXSPD6t1vjiNdnIYAMpiOQbodCGxAnq6jnNyrjEzffdq3qw+5IkFNdG4 7Pw=
+SECTION ADDITIONAL
+rhino.cis.vutbr.cz.	86400	IN	A	147.229.3.10
+rhino.cis.vutbr.cz.	86400	IN	AAAA	2001:67c:1220:e000::93e5:30a
+shark.ro.vutbr.cz.	3600	IN	A	147.229.2.59
+pipit.cis.vutbr.cz.	86400	IN	A	77.93.219.110
+pipit.cis.vutbr.cz.	86400	IN	AAAA	2a01:430:120::4d5d:db6e
+rhino.cis.vutbr.cz.	86400	IN	RRSIG	A 5 4 86400 20170204080646 20170105080646 28257 cis.vutbr.cz. X/tDf8e3JEV0LxiItfpQnBzeaRIq693VG8d30iCH4/1I0uqyCfxboWmm /CBpn9A8MCJu9NEEv+4+povNlfUfqi2yjsqJEVj8ztHxD4g9cc284Cv6 ySjxrSZ9axVqoaopEXujiTwwWJUFcgF6pxqyXVksW7sgKJrboM4VSlQD +Sw=
+rhino.cis.vutbr.cz.	86400	IN	RRSIG	AAAA 5 4 86400 20170204080646 20170105080646 28257 cis.vutbr.cz. T3Yf5PAkSeJtoOH90ea9zZBG9FC3iFhiCSerDn6d9up8GRfzxDsavYJC zQu+3vnOySySn+3TMzQSSFcWdJC2iO7ulaDGr177Gof9QJbKSVSMW7jt YDE2f4/R4Go3NZVwjk/HfpCInoR6pHNA1s/9hMnWtiVopmBdfzyd3/sW YOU=
+shark.ro.vutbr.cz.	3600	IN	RRSIG	A 5 4 3600 20170222120032 20170123120032 12150 ro.vutbr.cz. SmhgyF48yX/6yH7AdSmGX60NL/xaiKH/oAzB0rnPfQZ6j+UfV57ginVV lj798K9A8jjucUpqE8ua2mZ6/aOhpqlV2iI0CZXG44zOupsCY1/OXBDx YNetBcjoXDQCBQRLLLEUL5FerDVxqT74ngdLdKubwRdrB0TLQlvpBr+F Tc8=
+pipit.cis.vutbr.cz.	86400	IN	RRSIG	A 5 4 86400 20170204080646 20170105080646 28257 cis.vutbr.cz. Cz9etHnEOQTzu+6rYJEqx/SQ1tQgPOCyf8HSj4KOsx89jtgiHNC6pep6 ZE0SphMGAs3jC/uGIhlaFNZ3i38OQIMuqwacbz+XZyW5bByvV3QZrhqh dFxMDfmPuNiCAT3crFpUkvVW1OE3YfGHzZGXX7JP5wb1b8A3X6Qih7fV +nQ=
+pipit.cis.vutbr.cz.	86400	IN	RRSIG	AAAA 5 4 86400 20170204080646 20170105080646 28257 cis.vutbr.cz. piafjh6my2fooZRrzwCu9RQ95gYaMQkhIkDaGX/fT6wXzSdmgFZkS1Nl EMIKdDCQaPrLGMG3p32ptMkAm4esPekeyNtLSMBtXwZyUkgEGn6h1QM2 Yr3TOo8cixfk5nmRRdlYadf5krLb8yI9exiqeymgEQLa1YNRz/bWArlX bn8=
+ENTRY_END
+
+ENTRY_BEGIN
+MATCH opcode qtype qname
+ADJUST copy_id
+REPLY QR AA DO
+SECTION QUESTION
+ro.vutbr.cz.       		IN      DS
+SECTION ANSWER
+ro.vutbr.cz.		28800	IN	DS	16627 5 2 1AEE56EAF9D01A51C8C524E55A7FAE0E27207911F0FA6126052CE5B3 39335FC8
+ro.vutbr.cz.		28800	IN	DS	16627 5 1 BFDFD0FB1EDFCEBFB9ECB13C93F9CA65755217BA
+ro.vutbr.cz.		28800	IN	RRSIG	DS 5 3 28800 20170216060902 20170117060902 39756 vutbr.cz. OOJfGI14bRHqeWhRLMOa75pfHo+clR4rMJpvO3PPjmheownqy2awA7u3 xR5FJko7A6e+difoJdAWCMzN7x1qcrd1htOOKOc7wtcb+QC2JH8B/e0G 0gNPw2UKsFL1Qw9HQkSqxyIaCGg3nMLO1hh3AVccZadw2f/jLpAzw5/1 pLA=
+ENTRY_END
+
+ENTRY_BEGIN
+MATCH opcode qtype qname
+ADJUST copy_id
+REPLY QR AA DO
+SECTION QUESTION
+ro.vutbr.cz.       		IN      DNSKEY
+SECTION ANSWER
+ro.vutbr.cz.		3600	IN	DNSKEY	256 3 5 AwEAAb4tyN4pqltB48s1xQS3ZPXnTZJMvgXxiouXU9xtzj4wnhjhZp45 H7ozslWuksrwQWhZ8AASAD5kPFbQRbwpQ7xbEb3xdKHaWCFpyRCTkrqa ZQZQy4gaVqO+oRW42dIQ9K08A/WfvRuRDtw3VWDATp9pUkgpvb1n6+lp 71YK19RX
+ro.vutbr.cz.		3600	IN	DNSKEY	257 3 5 AwEAAef6bqTAl94KddNHvit41gw6QBKkiYjUeS+UP58VHybV29RC7sSE +rYmkXabaMOLmoqMQRMepBEaUdM5OoZBWibHrPAbG0Wf+vlMOoWD5+EC 2mCxrUntIlOuS4XpMTh22+l0k1xSPiMGKjY0BDR95Iu3dDezCVl9PkPp tHj/rAnRTH7Q0fH9Mip8sigosd/CmsoY03I0AcZT4z1+XpGsq5Npxwtj 7cz0SRTI/eV5nynNYK+vr6kOfU1fw7p8/wxIfXkks0Xy8ktXa26DFdw1 RoqVlTS1s1diFyF5niCOT6Ei2kAlf0fggZJBypwoK+6J42wwD2OhORX+ lKrhooaN4TU9AcHwgv25XTXhUq4tYh+veazdXNWDjEb3ZyLM8fKERCa9 YtDBFoHM7yFOHbsOhHKMn8F6T2Boi73hU/+wspjL/n8taKevyyygGg+U g4ugo2pTIouAs5DNnv+nUrpctcKZ5nMEUVl+3XBsXplIyz9QEKHWdFzL gyfIZEok8WdYHebcIy1vJrxzqCNw9ixnTn+OK1lwlMToVH1AGpvRKRPo wGSFaIrDyXxKul34j2jEhP9TWRcJqncy166Ueu3c0BKmclM29N8jeWbP 3TqRJ3RRxNj/vk6c/UGmmrHEz8YdNp2L0hv3JgItr2GujCvPApUvLNPW C7DSErQ3JsjV3gah
+ro.vutbr.cz.		3600	IN	RRSIG	DNSKEY 5 3 3600 20170222120032 20170123120032 12150 ro.vutbr.cz. pN+8YElj24dhtnOQ20sjWxJTjx+FLTMrPms1lWIJKZtp2evQBG5AnAep 6w0QeMUTIh9ter58Dh6wu2IN4uA1h3ThxnSgwLraOChUFBtPTO8h5y8J mAq4KXSfqbEcHzZO/nBAtxSUk7aUz7yWf09xE+iozW3ORRWIXovMYci5 eEw=
+ro.vutbr.cz.		3600	IN	RRSIG	DNSKEY 5 3 3600 20170222120032 20170123120032 16627 ro.vutbr.cz. DSaIAl+iyToM8+ai9xuRVcRshYyI66XHWkOz0XEbIAwbc8aEMEeFCA91 1vpuBb6H92MXvM8hYsBhZHNIA0ApoIE4bdyEGZY05XN3GYgJ4BEhXJVM RR+inJf+vGGqdlRP6F2sPO+rCqfxWBvSoUFU7DpCpkl7hz2Ex0Clm9C9 YnWgL+tGmAH33s2Y8lTA3hG/0W0NxD5zy1LiyDa8Ls3vV4MC6gVxyloT Capd8FkDL9PmgW0gMRNtIWmc5Hw+j/HRMoy+oRCe8PIfUL/Dpx3iTAH8 iN3wV8apV2uPa0L8QgpixK4Tc87aSainCopVY+NOc5t0HErUzj8i7qA9 J/cRtQvlUzln5vBsrQsVIzIeNV4o8/cM3zFyfdKkHh1tWYKLJKkjfXc5 +7VMvF8PnoHceT/Zr2gCc8tnygRobypzgqy3p69bRJqiT0/eCAgpGusV 1DCOJY0sdiGDZEtpqeINbAgGKAMmmNwjIwYSFowRzdawip1wNd+90RhI +8hvx8Sc5+K5Mom2BF2wGHf/2Kv/ArzyXxqqcNozM61L1AjxIsBHjnLZ TzPlLntmiHUVaqET9Yc3G0K/RdsIpqz4M79N0BX66a58x2a3fLqQdrEC QshZPNxk2S4eCsrVRjHvU4a7e74Rbf/zXp89Y+jmwBbDMdnp+2/h9s6U J0sEBCYyo9M=
+ENTRY_END
+
+ENTRY_BEGIN
+MATCH opcode qtype qname
+ADJUST copy_id
+REPLY QR AA DO
+SECTION QUESTION
+piranha.ro.vutbr.cz.		IN	A
+SECTION ANSWER
+piranha.ro.vutbr.cz.	3600	IN	A	147.229.2.90
+piranha.ro.vutbr.cz.	3600	IN	RRSIG	A 5 4 3600 20170222120032 20170123120032 12150 ro.vutbr.cz. Jz8bcAADQjCKTCcF70IK1aHGQlM4ukyN0myABlxoPaqid1mHX5jwR91b kdQmUAh2xDitlgRLbFjbUUgmjSPzQ5Qt7GAFUsVmqxvjbOLZjqHER1dh zmiWO0fDvvP647Osv3RiAP822rNUJcJrUBZU9LmeP05gwIHcpJrhdVBT b7I=
+SECTION AUTHORITY
+ro.vutbr.cz.		86400	IN	NS	shark.ro.vutbr.cz.
+ro.vutbr.cz.		86400	IN	NS	rhino.cis.vutbr.cz.
+ro.vutbr.cz.		86400	IN	NS	pipit.cis.vutbr.cz.
+ro.vutbr.cz.		86400	IN	RRSIG	NS 5 3 86400 20170222120032 20170123120032 12150 ro.vutbr.cz. HAQ8A+QNsS1WIXdW/fbT3jP+IxObBBvgUmvzsmJBXo8HMtnMAcuCQGmB 2JBQsQethQXsdyLnMK8to/5A9VRkqkAa7edxUoy7SdDi/mzGeLAVhF+5 kXSPD6t1vjiNdnIYAMpiOQbodCGxAnq6jnNyrjEzffdq3qw+5IkFNdG4 7Pw=
+SECTION ADDITIONAL
+rhino.cis.vutbr.cz.	86400	IN	A	147.229.3.10
+rhino.cis.vutbr.cz.	86400	IN	AAAA	2001:67c:1220:e000::93e5:30a
+shark.ro.vutbr.cz.	3600	IN	A	147.229.2.59
+pipit.cis.vutbr.cz.	86400	IN	A	77.93.219.110
+pipit.cis.vutbr.cz.	86400	IN	AAAA	2a01:430:120::4d5d:db6e
+rhino.cis.vutbr.cz.	86400	IN	RRSIG	A 5 4 86400 20170204080646 20170105080646 28257 cis.vutbr.cz. X/tDf8e3JEV0LxiItfpQnBzeaRIq693VG8d30iCH4/1I0uqyCfxboWmm /CBpn9A8MCJu9NEEv+4+povNlfUfqi2yjsqJEVj8ztHxD4g9cc284Cv6 ySjxrSZ9axVqoaopEXujiTwwWJUFcgF6pxqyXVksW7sgKJrboM4VSlQD +Sw=
+rhino.cis.vutbr.cz.	86400	IN	RRSIG	AAAA 5 4 86400 20170204080646 20170105080646 28257 cis.vutbr.cz. T3Yf5PAkSeJtoOH90ea9zZBG9FC3iFhiCSerDn6d9up8GRfzxDsavYJC zQu+3vnOySySn+3TMzQSSFcWdJC2iO7ulaDGr177Gof9QJbKSVSMW7jt YDE2f4/R4Go3NZVwjk/HfpCInoR6pHNA1s/9hMnWtiVopmBdfzyd3/sW YOU=
+shark.ro.vutbr.cz.	3600	IN	RRSIG	A 5 4 3600 20170222120032 20170123120032 12150 ro.vutbr.cz. SmhgyF48yX/6yH7AdSmGX60NL/xaiKH/oAzB0rnPfQZ6j+UfV57ginVV lj798K9A8jjucUpqE8ua2mZ6/aOhpqlV2iI0CZXG44zOupsCY1/OXBDx YNetBcjoXDQCBQRLLLEUL5FerDVxqT74ngdLdKubwRdrB0TLQlvpBr+F Tc8=
+pipit.cis.vutbr.cz.	86400	IN	RRSIG	A 5 4 86400 20170204080646 20170105080646 28257 cis.vutbr.cz. Cz9etHnEOQTzu+6rYJEqx/SQ1tQgPOCyf8HSj4KOsx89jtgiHNC6pep6 ZE0SphMGAs3jC/uGIhlaFNZ3i38OQIMuqwacbz+XZyW5bByvV3QZrhqh dFxMDfmPuNiCAT3crFpUkvVW1OE3YfGHzZGXX7JP5wb1b8A3X6Qih7fV +nQ=
+pipit.cis.vutbr.cz.	86400	IN	RRSIG	AAAA 5 4 86400 20170204080646 20170105080646 28257 cis.vutbr.cz. piafjh6my2fooZRrzwCu9RQ95gYaMQkhIkDaGX/fT6wXzSdmgFZkS1Nl EMIKdDCQaPrLGMG3p32ptMkAm4esPekeyNtLSMBtXwZyUkgEGn6h1QM2 Yr3TOo8cixfk5nmRRdlYadf5krLb8yI9exiqeymgEQLa1YNRz/bWArlX bn8=
+ENTRY_END
+
+; end of pipit.cis.vutbr.cz. & rhino.cis.vutbr.cz.
+RANGE_END
+
+
+STEP 1 QUERY
+ENTRY_BEGIN
+REPLY RD
+SECTION QUESTION
+www.vutbr.cz. IN A
+ENTRY_END
+
+; recursion happens here.
+STEP 10 CHECK_ANSWER
+ENTRY_BEGIN
+MATCH flags rcode question answer
+REPLY QR RD RA NOERROR
+SECTION QUESTION
+www.vutbr.cz.		IN	A
+SECTION ANSWER
+www.vutbr.cz.		IN	CNAME	piranha.ro.vutbr.cz.
+piranha.ro.vutbr.cz.	IN	A	147.229.2.90
+ENTRY_END
+
+STEP 20 QUERY
+ENTRY_BEGIN
+REPLY RD DO
+SECTION QUESTION
+www.vutbr.cz.		IN	A
+ENTRY_END
+
+STEP 21 CHECK_ANSWER
+ENTRY_BEGIN
+MATCH flags rcode question answer
+REPLY QR RD RA AD NOERROR
+SECTION QUESTION
+www.vutbr.cz.		IN	A
+SECTION ANSWER
+www.vutbr.cz.		IN	CNAME	piranha.ro.vutbr.cz.
+www.vutbr.cz.		IN	RRSIG	CNAME 5 3 300 20170216060902 20170117060902 39756 vutbr.cz. 9B3UC5SOEw1+yKlYlOTINEuNq0Kdglywc5IYJwzeSzQ3ykptzZo3ABSy bYhTqImVkhm/4NFM9/4HWMHPDzTmrWS0mCI/ljCd/oe/PxW/uESvo4P5 EQzlcuH6xBzc1KdEFAJOSmRzFjj3vyK1QN3k/c+1y2oMFOYOR2oOzCw+ MIE=
+piranha.ro.vutbr.cz.	IN	A	147.229.2.90
+piranha.ro.vutbr.cz.	3600	IN	RRSIG	A 5 4 3600 20170222120032 20170123120032 12150 ro.vutbr.cz. Jz8bcAADQjCKTCcF70IK1aHGQlM4ukyN0myABlxoPaqid1mHX5jwR91b kdQmUAh2xDitlgRLbFjbUUgmjSPzQ5Qt7GAFUsVmqxvjbOLZjqHER1dh zmiWO0fDvvP647Osv3RiAP822rNUJcJrUBZU9LmeP05gwIHcpJrhdVBT b7I=
+ENTRY_END
+
+SCENARIO_END
diff --git a/lib/cache/peek.c b/lib/cache/peek.c
new file mode 100644
index 0000000..dc7cd7f
--- /dev/null
+++ b/lib/cache/peek.c
@@ -0,0 +1,796 @@
+/*  Copyright (C) 2018 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#include "lib/cache/impl.h"
+
+#include "lib/dnssec/ta.h"
+#include "lib/layer/iterate.h"
+
+/* The whole file only exports peek_nosync().
+ * Forwards for larger chunks of code: */
+
+static int found_exact_hit(kr_layer_t *ctx, knot_pkt_t *pkt, knot_db_val_t val,
+			   uint8_t lowest_rank);
+static int closest_NS(struct kr_cache *cache, struct key *k, entry_list_t el,
+			struct kr_query *qry, bool only_NS, bool is_DS);
+static int answer_simple_hit(kr_layer_t *ctx, knot_pkt_t *pkt, uint16_t type,
+		const struct entry_h *eh, const void *eh_bound, uint32_t new_ttl);
+static int answer_dname_hit(kr_layer_t *ctx, knot_pkt_t *pkt, const knot_dname_t *dname_owner,
+		const struct entry_h *eh, const void *eh_bound, uint32_t new_ttl);
+static int try_wild(struct key *k, struct answer *ans, const knot_dname_t *clencl_name,
+		    uint16_t type, uint8_t lowest_rank,
+		    const struct kr_query *qry, struct kr_cache *cache);
+
+static int peek_encloser(
+	struct key *k, struct answer *ans, int sname_labels,
+	uint8_t lowest_rank, const struct kr_query *qry, struct kr_cache *cache);
+
+
+static int nsec_p_init(struct nsec_p *nsec_p, knot_db_val_t nsec_p_entry, bool with_knot)
+{
+	const size_t stamp_len = sizeof(uint32_t);
+	if (nsec_p_entry.len <= stamp_len) { /* plain NSEC if equal */
+		nsec_p->raw = NULL;
+		nsec_p->hash = 0;
+		return kr_ok();
+	}
+	nsec_p->raw = (uint8_t *)nsec_p_entry.data + stamp_len;
+	nsec_p->hash = nsec_p_mkHash(nsec_p->raw);
+	if (!with_knot) return kr_ok();
+	/* Convert NSEC3 params to another format. */
+	const dnssec_binary_t rdata = {
+		.size = nsec_p_rdlen(nsec_p->raw),
+		.data = (uint8_t *)/*const-cast*/nsec_p->raw,
+	};
+	int ret = dnssec_nsec3_params_from_rdata(&nsec_p->libknot, &rdata);
+	return ret == DNSSEC_EOK ? kr_ok() : kr_error(ret);
+}
+
+static void nsec_p_cleanup(struct nsec_p *nsec_p)
+{
+	dnssec_binary_free(&nsec_p->libknot.salt);
+	/* We don't really need to clear it, but it's not large. (`salt` zeroed above) */
+	memset(nsec_p, 0, sizeof(*nsec_p));
+}
+
+/** Compute new TTL for nsec_p entry, using SOA serial arith.
+ * \param new_ttl (optionally) write the new TTL (even if negative)
+ * \return error code, e.g. kr_error(ESTALE) */
+static int nsec_p_ttl(knot_db_val_t entry, const uint32_t timestamp, int32_t *new_ttl)
+{
+	if (!entry.data) {
+		assert(!EINVAL);
+		return kr_error(EINVAL);
+	}
+	uint32_t stamp;
+	if (!entry.len) {
+		return kr_error(ENOENT);
+	}
+	if (entry.len < sizeof(stamp)) {
+		assert(!EILSEQ);
+		return kr_error(EILSEQ);
+	}
+	memcpy(&stamp, entry.data, sizeof(stamp));
+	int32_t newttl = stamp - timestamp;
+	if (new_ttl) *new_ttl = newttl;
+	return newttl < 0 ? kr_error(ESTALE) : kr_ok();
+}
+
+static uint8_t get_lowest_rank(const struct kr_query *qry, const knot_dname_t *name, const uint16_t type)
+{
+	/* Shut up linters. */
+	if (unlikely(!qry || !qry->request)) abort();
+	/* TODO: move rank handling into the iterator (DNSSEC_* flags)? */
+	const bool allow_unverified =
+		knot_wire_get_cd(qry->request->qsource.packet->wire) || qry->flags.STUB;
+		/* in stub mode we don't trust RRs anyway ^^ */
+	if (qry->flags.NONAUTH) {
+		return KR_RANK_INITIAL;
+		/* Note: there's little sense in validation status for non-auth records.
+		 * In case of using NONAUTH to get NS IPs, knowing that you ask correct
+		 * IP doesn't matter much for security; it matters whether you can
+		 * validate the answers from the NS.
+		 */
+	} else if (!allow_unverified) {
+		/* Records not present under any TA don't have their security
+		 * verified at all, so we also accept low ranks in that case. */
+		const bool ta_covers = kr_ta_covers_qry(qry->request->ctx, name, type);
+		/* ^ TODO: performance?  TODO: stype - call sites */
+		if (ta_covers) {
+			return KR_RANK_INSECURE | KR_RANK_AUTH;
+		} /* else falltrhough */
+	}
+	return KR_RANK_INITIAL | KR_RANK_AUTH;
+}
+
+
+/** Almost whole .produce phase for the cache module.
+ * \note we don't transition to KR_STATE_FAIL even in case of "unexpected errors".
+ */
+int peek_nosync(kr_layer_t *ctx, knot_pkt_t *pkt)
+{
+	struct kr_request *req = ctx->req;
+	struct kr_query *qry = req->current_query;
+	struct kr_cache *cache = &req->ctx->cache;
+
+	struct key k_storage, *k = &k_storage;
+	int ret = kr_dname_lf(k->buf, qry->sname, false);
+	if (unlikely(ret)) {
+		assert(false);
+		return ctx->state;
+	}
+
+	const uint8_t lowest_rank = get_lowest_rank(qry, qry->sname, qry->stype);
+
+	/**** 1. find the name or the closest (available) zone, not considering wildcards
+	 **** 1a. exact name+type match (can be negative, mainly in insecure zones) */
+	{
+		knot_db_val_t key = key_exact_type_maypkt(k, qry->stype);
+		knot_db_val_t val = { NULL, 0 };
+		ret = cache_op(cache, read, &key, &val, 1);
+		if (!ret) {
+			/* found an entry: test conditions, materialize into pkt, etc. */
+			ret = found_exact_hit(ctx, pkt, val, lowest_rank);
+		}
+	}
+	if (ret && ret != -abs(ENOENT)) {
+		VERBOSE_MSG(qry, "=> exact hit error: %d %s\n", ret, kr_strerror(ret));
+		assert(false);
+		return ctx->state;
+	} else if (!ret) {
+		return KR_STATE_DONE;
+	}
+
+	/**** 1b. otherwise, find the longest prefix zone/xNAME (with OK time+rank). [...] */
+	k->zname = qry->sname;
+	ret = kr_dname_lf(k->buf, k->zname, false); /* LATER(optim.): probably remove */
+	if (unlikely(ret)) {
+		assert(false);
+		return ctx->state;
+	}
+	entry_list_t el;
+	ret = closest_NS(cache, k, el, qry, false, qry->stype == KNOT_RRTYPE_DS);
+	if (ret) {
+		assert(ret == kr_error(ENOENT));
+		if (ret != kr_error(ENOENT) || !el[0].len) {
+			return ctx->state;
+		}
+	}
+	switch (k->type) {
+	case KNOT_RRTYPE_CNAME: {
+		const knot_db_val_t v = el[EL_CNAME];
+		assert(v.data && v.len);
+		const int32_t new_ttl = get_new_ttl(v.data, qry, qry->sname,
+						KNOT_RRTYPE_CNAME, qry->timestamp.tv_sec);
+		ret = answer_simple_hit(ctx, pkt, KNOT_RRTYPE_CNAME, v.data,
+					knot_db_val_bound(v), new_ttl);
+		return ret == kr_ok() ? KR_STATE_DONE : ctx->state;
+		}
+	case KNOT_RRTYPE_DNAME: {
+		const knot_db_val_t v = el[EL_DNAME];
+		assert(v.data && v.len);
+		/* TTL: for simplicity, we just ask for TTL of the generated CNAME. */
+		const int32_t new_ttl = get_new_ttl(v.data, qry, qry->sname,
+						KNOT_RRTYPE_CNAME, qry->timestamp.tv_sec);
+		ret = answer_dname_hit(ctx, pkt, k->zname, v.data,
+					knot_db_val_bound(v), new_ttl);
+		return ret == kr_ok() ? KR_STATE_DONE : ctx->state;
+		}
+	}
+
+	/* We have to try proving from NSEC*. */
+	auto_free char *log_zname = NULL;
+	WITH_VERBOSE(qry) {
+		log_zname = kr_dname_text(k->zname);
+		if (!el[0].len) {
+			VERBOSE_MSG(qry, "=> no NSEC* cached for zone: %s\n", log_zname);
+		}
+	}
+
+#if 0
+	if (!eh) { /* fall back to root hints? */
+		ret = kr_zonecut_set_sbelt(req->ctx, &qry->zone_cut);
+		if (ret) return ctx->state;
+		assert(!qry->zone_cut.parent);
+
+		//VERBOSE_MSG(qry, "=> using root hints\n");
+		//qry->flags.AWAIT_CUT = false;
+		return ctx->state;
+	}
+
+	/* Now `eh` points to the closest NS record that we've found,
+	 * and that's the only place to start - we may either find
+	 * a negative proof or we may query upstream from that point. */
+	kr_zonecut_set(&qry->zone_cut, k->zname);
+	ret = kr_make_query(qry, pkt); // TODO: probably not yet - qname minimization
+	if (ret) return ctx->state;
+#endif
+
+	/** Structure for collecting multiple NSEC* + RRSIG records,
+	 * in preparation for the answer, and for tracking the progress. */
+	struct answer ans;
+	memset(&ans, 0, sizeof(ans));
+	ans.mm = &pkt->mm;
+	const int sname_labels = knot_dname_labels(qry->sname, NULL);
+
+	/* Try the NSEC* parameters in order, until success.
+	 * Let's not mix different parameters for NSEC* RRs in a single proof. */
+	for (int i = 0; ;) {
+		int32_t log_new_ttl = -123456789; /* visually recognizable value */
+		ret = nsec_p_ttl(el[i], qry->timestamp.tv_sec, &log_new_ttl);
+		if (!ret || VERBOSE_STATUS) {
+			nsec_p_init(&ans.nsec_p, el[i], !ret);
+		}
+		if (ret) {
+			VERBOSE_MSG(qry, "=> skipping zone: %s, %s, hash %x;"
+				"new TTL %d, ret %d\n",
+				log_zname, (ans.nsec_p.raw ? "NSEC3" : "NSEC"),
+				(unsigned)ans.nsec_p.hash, (int)log_new_ttl, ret);
+			/* no need for nsec_p_cleanup() in this case */
+			goto cont;
+		}
+		VERBOSE_MSG(qry, "=> trying zone: %s, %s, hash %x\n",
+				log_zname, (ans.nsec_p.raw ? "NSEC3" : "NSEC"),
+				(unsigned)ans.nsec_p.hash);
+		/**** 2. and 3. inside */
+		ret = peek_encloser(k, &ans, sname_labels,
+					lowest_rank, qry, cache);
+		nsec_p_cleanup(&ans.nsec_p);
+		if (!ret) break;
+		if (ret < 0) return ctx->state;
+	cont:
+		/* Otherwise we try another nsec_p, if available. */
+		if (++i == ENTRY_APEX_NSECS_CNT) return ctx->state;
+		/* clear possible partial answers in `ans` (no need to deallocate) */
+		ans.rcode = 0;
+		memset(&ans.rrsets, 0, sizeof(ans.rrsets));
+	}
+
+	/**** 4. add SOA iff needed */
+	if (ans.rcode != PKT_NOERROR) {
+		/* Assuming k->buf still starts with zone's prefix,
+		 * look up the SOA in cache. */
+		k->buf[0] = k->zlf_len;
+		knot_db_val_t key = key_exact_type(k, KNOT_RRTYPE_SOA);
+		knot_db_val_t val = { NULL, 0 };
+		ret = cache_op(cache, read, &key, &val, 1);
+		const struct entry_h *eh;
+		if (ret || !(eh = entry_h_consistent_E(val, KNOT_RRTYPE_SOA))) {
+			assert(ret); /* only want to catch `eh` failures */
+			VERBOSE_MSG(qry, "=> SOA missed\n");
+			return ctx->state;
+		}
+		/* Check if the record is OK. */
+		int32_t new_ttl = get_new_ttl(eh, qry, k->zname, KNOT_RRTYPE_SOA,
+						qry->timestamp.tv_sec);
+		if (new_ttl < 0 || eh->rank < lowest_rank || eh->is_packet) {
+			VERBOSE_MSG(qry, "=> SOA unfit %s: rank 0%.2o, new TTL %d\n",
+					(eh->is_packet ? "packet" : "RR"),
+					eh->rank, new_ttl);
+			return ctx->state;
+		}
+		/* Add the SOA into the answer. */
+		ret = entry2answer(&ans, AR_SOA, eh, knot_db_val_bound(val),
+				   k->zname, KNOT_RRTYPE_SOA, new_ttl);
+		if (ret) return ctx->state;
+	}
+
+	/* Find our target RCODE. */
+	int real_rcode;
+	switch (ans.rcode) {
+	case PKT_NODATA:
+	case PKT_NOERROR: /* positive wildcarded response */
+		real_rcode = KNOT_RCODE_NOERROR;
+		break;
+	case PKT_NXDOMAIN:
+		real_rcode = KNOT_RCODE_NXDOMAIN;
+		break;
+	default:
+		assert(false);
+	case 0: /* i.e. nothing was found */
+		/* LATER(optim.): zone cut? */
+		VERBOSE_MSG(qry, "=> cache miss\n");
+		return ctx->state;
+	}
+
+	if (pkt_renew(pkt, qry->sname, qry->stype)
+	    || knot_pkt_begin(pkt, KNOT_ANSWER)
+	   ) {
+		assert(false);
+		return ctx->state;
+	}
+	knot_wire_set_rcode(pkt->wire, real_rcode);
+
+	bool expiring = false; // TODO
+	for (int i = 0; i < sizeof(ans.rrsets) / sizeof(ans.rrsets[0]); ++i) {
+		if (i == 1) knot_pkt_begin(pkt, KNOT_AUTHORITY);
+		if (!ans.rrsets[i].set.rr) continue;
+		expiring = expiring || ans.rrsets[i].set.expiring;
+		ret = pkt_append(pkt, &ans.rrsets[i], ans.rrsets[i].set.rank);
+		if (ret) {
+			assert(false);
+			return ctx->state;
+		}
+	}
+
+	/* Finishing touches. */
+	struct kr_qflags * const qf = &qry->flags;
+	qf->EXPIRING = expiring;
+	qf->CACHED = true;
+	qf->NO_MINIMIZE = true;
+
+	return KR_STATE_DONE;
+}
+
+/**
+ * This is where the high-level "business logic" of aggressive cache is.
+ * \return 0: success (may need SOA);  >0: try other nsec_p;  <0: exit cache immediately.
+ */
+static int peek_encloser(
+	struct key *k, struct answer *ans, const int sname_labels,
+	uint8_t lowest_rank, const struct kr_query *qry, struct kr_cache *cache)
+{
+	/** Start of NSEC* covering the sname;
+	 * it's part of key - the one within zone (read only) */
+	knot_db_val_t cover_low_kwz = { NULL, 0 };
+	knot_dname_t cover_hi_storage[KNOT_DNAME_MAXLEN];
+	/** End of NSEC* covering the sname. */
+	knot_db_val_t cover_hi_kwz = {
+		.data = cover_hi_storage,
+		.len = sizeof(cover_hi_storage),
+	};
+
+	/**** 2. Find a closest (provable) encloser (of sname). */
+	int clencl_labels = -1;
+	bool clencl_is_tentative = false;
+	if (!ans->nsec_p.raw) { /* NSEC */
+		int ret = nsec1_encloser(k, ans, sname_labels, &clencl_labels,
+					 &cover_low_kwz, &cover_hi_kwz, qry, cache);
+		if (ret) return ret;
+	} else {
+		int ret = nsec3_encloser(k, ans, sname_labels, &clencl_labels,
+					 qry, cache);
+		clencl_is_tentative = ret == ABS(ENOENT) && clencl_labels >= 0;
+		/* ^^ Last chance: *positive* wildcard record under this clencl. */
+		if (ret && !clencl_is_tentative) return ret;
+	}
+
+	/* We should have either a match or a cover at this point. */
+	if (ans->rcode != PKT_NODATA && ans->rcode != PKT_NXDOMAIN) {
+		assert(false);
+		return kr_error(EINVAL);
+	}
+	const bool ncloser_covered = ans->rcode == PKT_NXDOMAIN;
+
+	/** Name of the closest (provable) encloser. */
+	const knot_dname_t *clencl_name = qry->sname;
+	for (int l = sname_labels; l > clencl_labels; --l)
+		clencl_name = knot_wire_next_label(clencl_name, NULL);
+
+	/**** 3. source of synthesis checks, in case the next closer name was covered.
+	 **** 3a. We want to query for NSEC* of source of synthesis (SS) or its
+	 * predecessor, providing us with a proof of its existence or non-existence. */
+	if (ncloser_covered && !ans->nsec_p.raw) {
+		int ret = nsec1_src_synth(k, ans, clencl_name,
+					  cover_low_kwz, cover_hi_kwz, qry, cache);
+		if (ret == AR_SOA) return 0;
+		assert(ret <= 0);
+		if (ret) return ret;
+
+	} else if (ncloser_covered && ans->nsec_p.raw && !clencl_is_tentative) {
+		int ret = nsec3_src_synth(k, ans, clencl_name, qry, cache);
+		if (ret == AR_SOA) return 0;
+		assert(ret <= 0);
+		if (ret) return ret;
+
+	} /* else (!ncloser_covered) so no wildcard checks needed,
+	   * as we proved that sname exists. */
+
+	/**** 3b. find wildcarded answer, if next closer name was covered
+	 * and we don't have a full proof yet.  (common for NSEC*) */
+	if (!ncloser_covered)
+		return kr_ok(); /* decrease indentation */
+	/* Construct key for exact qry->stype + source of synthesis. */
+	int ret = kr_dname_lf(k->buf, clencl_name, true);
+	if (ret) {
+		assert(!ret);
+		return kr_error(ret);
+	}
+	const uint16_t types[] = { qry->stype, KNOT_RRTYPE_CNAME };
+	for (int i = 0; i < (2 - (qry->stype == KNOT_RRTYPE_CNAME)); ++i) {
+		ret = try_wild(k, ans, clencl_name, types[i],
+				lowest_rank, qry, cache);
+		if (ret == kr_ok()) {
+			return kr_ok();
+		} else if (ret != -ABS(ENOENT) && ret != -ABS(ESTALE)) {
+			assert(false);
+			return kr_error(ret);
+		}
+		/* else continue */
+	}
+	/* Neither attempt succeeded, but the NSEC* proofs were found,
+	 * so skip trying other parameters, as it seems very unlikely
+	 * to turn out differently than by the same wildcard search. */
+	return -ABS(ENOENT);
+}
+
+static void answer_simple_qflags(struct kr_qflags *qf, const struct entry_h *eh,
+				 uint32_t new_ttl)
+{
+	/* Finishing touches. */
+	qf->EXPIRING = is_expiring(eh->ttl, new_ttl);
+	qf->CACHED = true;
+	qf->NO_MINIMIZE = true;
+	qf->DNSSEC_INSECURE = kr_rank_test(eh->rank, KR_RANK_INSECURE);
+	if (qf->DNSSEC_INSECURE) {
+		qf->DNSSEC_WANT = false;
+	}
+}
+
+#define CHECK_RET(ret) do { \
+	if ((ret) < 0) { assert(false); return kr_error((ret)); } \
+} while (false)
+
+static int answer_simple_hit(kr_layer_t *ctx, knot_pkt_t *pkt, uint16_t type,
+		const struct entry_h *eh, const void *eh_bound, uint32_t new_ttl)
+{
+	struct kr_request *req = ctx->req;
+	struct kr_query *qry = req->current_query;
+
+	/* All OK, so start constructing the (pseudo-)packet. */
+	int ret = pkt_renew(pkt, qry->sname, qry->stype);
+	CHECK_RET(ret);
+
+	/* Materialize the sets for the answer in (pseudo-)packet. */
+	struct answer ans;
+	memset(&ans, 0, sizeof(ans));
+	ans.mm = &pkt->mm;
+	ret = entry2answer(&ans, AR_ANSWER, eh, eh_bound,
+			   qry->sname, type, new_ttl);
+	CHECK_RET(ret);
+	/* Put links to the materialized data into the pkt. */
+	ret = pkt_append(pkt, &ans.rrsets[AR_ANSWER], eh->rank);
+	CHECK_RET(ret);
+
+	answer_simple_qflags(&qry->flags, eh, new_ttl);
+
+	VERBOSE_MSG(qry, "=> satisfied by exact %s: rank 0%.2o, new TTL %d\n",
+			(type == KNOT_RRTYPE_CNAME ? "CNAME" : "RRset"),
+			eh->rank, new_ttl);
+	return kr_ok();
+}
+
+static int answer_dname_hit(kr_layer_t *ctx, knot_pkt_t *pkt, const knot_dname_t *dname_owner,
+		const struct entry_h *eh, const void *eh_bound, uint32_t new_ttl)
+{
+	struct kr_request *req = ctx->req;
+	struct kr_query *qry = req->current_query;
+
+	/* All OK, so start constructing the (pseudo-)packet. */
+	int ret = pkt_renew(pkt, qry->sname, qry->stype);
+	CHECK_RET(ret);
+
+	/* Materialize the DNAME for the answer in (pseudo-)packet. */
+	struct answer ans;
+	memset(&ans, 0, sizeof(ans));
+	ans.mm = &pkt->mm;
+	ret = entry2answer(&ans, AR_ANSWER, eh, eh_bound,
+			   dname_owner, KNOT_RRTYPE_DNAME, new_ttl);
+	CHECK_RET(ret);
+	/* Put link to the RRset into the pkt. */
+	ret = pkt_append(pkt, &ans.rrsets[AR_ANSWER], eh->rank);
+	CHECK_RET(ret);
+	const knot_dname_t *dname_target =
+		knot_dname_target(ans.rrsets[AR_ANSWER].set.rr->rrs.rdata);
+
+	/* Generate CNAME RRset for the answer in (pseudo-)packet. */
+	const int AR_CNAME = AR_SOA;
+	knot_rrset_t *rr = ans.rrsets[AR_CNAME].set.rr
+		= knot_rrset_new(qry->sname, KNOT_RRTYPE_CNAME, KNOT_CLASS_IN,
+				 new_ttl, ans.mm);
+	CHECK_RET(rr ? kr_ok() : -ENOMEM);
+	const knot_dname_t *cname_target = knot_dname_replace_suffix(qry->sname,
+			knot_dname_labels(dname_owner, NULL), dname_target, ans.mm);
+	CHECK_RET(cname_target ? kr_ok() : -ENOMEM);
+	const int rdata_len = knot_dname_size(cname_target);
+
+	if (rdata_len <= KNOT_DNAME_MAXLEN
+	    && knot_dname_labels(cname_target, NULL) <= KNOT_DNAME_MAXLABELS) {
+		/* Normal case: the target name fits. */
+		rr->rrs.count = 1;
+		rr->rrs.size = knot_rdata_size(rdata_len);
+		rr->rrs.rdata = mm_alloc(ans.mm, rr->rrs.size);
+		CHECK_RET(rr->rrs.rdata ? kr_ok() : -ENOMEM);
+		knot_rdata_init(rr->rrs.rdata, rdata_len, cname_target);
+		/* Put link to the RRset into the pkt. */
+		ret = pkt_append(pkt, &ans.rrsets[AR_CNAME], eh->rank);
+		CHECK_RET(ret);
+	} else {
+		/* Note that it's basically a successful answer; name just doesn't fit. */
+		knot_wire_set_rcode(pkt->wire, KNOT_RCODE_YXDOMAIN);
+	}
+
+	answer_simple_qflags(&qry->flags, eh, new_ttl);
+	VERBOSE_MSG(qry, "=> satisfied by DNAME+CNAME: rank 0%.2o, new TTL %d\n",
+			eh->rank, new_ttl);
+	return kr_ok();
+}
+
+#undef CHECK_RET
+
+/** TODO: description; see the single call site for now. */
+static int found_exact_hit(kr_layer_t *ctx, knot_pkt_t *pkt, knot_db_val_t val,
+			   uint8_t lowest_rank)
+{
+	struct kr_request *req = ctx->req;
+	struct kr_query *qry = req->current_query;
+
+	int ret = entry_h_seek(&val, qry->stype);
+	if (ret) return ret;
+	const struct entry_h *eh = entry_h_consistent_E(val, qry->stype);
+	if (!eh) {
+		assert(false);
+		return kr_error(ENOENT);
+		// LATER: recovery in case of error, perhaps via removing the entry?
+		// LATER(optim): pehaps optimize the zone cut search
+	}
+
+	int32_t new_ttl = get_new_ttl(eh, qry, qry->sname, qry->stype,
+					qry->timestamp.tv_sec);
+	if (new_ttl < 0 || eh->rank < lowest_rank) {
+		/* Positive record with stale TTL or bad rank.
+		 * LATER(optim.): It's unlikely that we find a negative one,
+		 * so we might theoretically skip all the cache code. */
+
+		VERBOSE_MSG(qry, "=> skipping exact %s: rank 0%.2o (min. 0%.2o), new TTL %d\n",
+				eh->is_packet ? "packet" : "RR", eh->rank, lowest_rank, new_ttl);
+		return kr_error(ENOENT);
+	}
+
+	const uint8_t *eh_bound = knot_db_val_bound(val);
+	if (eh->is_packet) {
+		/* Note: we answer here immediately, even if it's (theoretically)
+		 * possible that we could generate a higher-security negative proof.
+		 * Rank is high-enough so we take it to save time searching;
+		 * in practice this also helps in some incorrect zones (live-signed). */
+		return answer_from_pkt  (ctx, pkt, qry->stype, eh, eh_bound, new_ttl);
+	} else {
+		return answer_simple_hit(ctx, pkt, qry->stype, eh, eh_bound, new_ttl);
+	}
+}
+
+
+/** Try to satisfy via wildcard (positively).  See the single call site. */
+static int try_wild(struct key *k, struct answer *ans, const knot_dname_t *clencl_name,
+		    const uint16_t type, const uint8_t lowest_rank,
+		    const struct kr_query *qry, struct kr_cache *cache)
+{
+	knot_db_val_t key = key_exact_type(k, type);
+	/* Find the record. */
+	knot_db_val_t val = { NULL, 0 };
+	int ret = cache_op(cache, read, &key, &val, 1);
+	if (!ret) {
+		ret = entry_h_seek(&val, type);
+	}
+	if (ret) {
+		if (ret != -ABS(ENOENT)) {
+			VERBOSE_MSG(qry, "=> wildcard: hit error %d %s\n",
+					ret, strerror(abs(ret)));
+			assert(false);
+		}
+		WITH_VERBOSE(qry) {
+			auto_free char *clencl_str = kr_dname_text(clencl_name),
+				*type_str = kr_rrtype_text(type);
+			VERBOSE_MSG(qry, "=> wildcard: not found: *.%s %s\n",
+					clencl_str, type_str);
+		}
+		return ret;
+	}
+	/* Check if the record is OK. */
+	const struct entry_h *eh = entry_h_consistent_E(val, type);
+	if (!eh) {
+		assert(false);
+		return kr_error(ret);
+		// LATER: recovery in case of error, perhaps via removing the entry?
+	}
+	int32_t new_ttl = get_new_ttl(eh, qry, qry->sname, type, qry->timestamp.tv_sec);
+		/* ^^ here we use the *expanded* wildcard name */
+	if (new_ttl < 0 || eh->rank < lowest_rank || eh->is_packet) {
+		/* Wildcard record with stale TTL, bad rank or packet.  */
+		VERBOSE_MSG(qry, "=> wildcard: skipping %s, rank 0%.2o, new TTL %d\n",
+				eh->is_packet ? "packet" : "RR", eh->rank, new_ttl);
+		return -ABS(ESTALE);
+	}
+	/* Add the RR into the answer. */
+	ret = entry2answer(ans, AR_ANSWER, eh, knot_db_val_bound(val),
+			   qry->sname, type, new_ttl);
+	VERBOSE_MSG(qry, "=> wildcard: answer expanded, ret = %d, new TTL %d\n",
+			ret, (int)new_ttl);
+	if (ret) return kr_error(ret);
+	ans->rcode = PKT_NOERROR;
+	return kr_ok();
+}
+
+int kr_cache_closest_apex(struct kr_cache *cache, const knot_dname_t *name, bool is_DS,
+			  knot_dname_t ** apex)
+{
+	if (!cache || !cache->db || !name || !apex || *apex) {
+		assert(!EINVAL);
+		return kr_error(EINVAL);
+	}
+	struct key k_storage, *k = &k_storage;
+	int ret = kr_dname_lf(k->buf, name, false);
+	if (ret)
+		return kr_error(ret);
+	entry_list_t el_;
+	k->zname = name;
+	ret = closest_NS(cache, k, el_, NULL, true, is_DS);
+	if (ret && ret != -abs(ENOENT))
+		return ret;
+	*apex = knot_dname_copy(k->zname, NULL);
+	if (!*apex)
+		return kr_error(ENOMEM);
+	return kr_ok();
+}
+
+/** \internal for closest_NS.  Check suitability of a single entry, setting k->type if OK.
+ * \return error code, negative iff whole list should be skipped.
+ */
+static int check_NS_entry(struct key *k, knot_db_val_t entry, int i,
+			  bool exact_match, bool is_DS,
+			  const struct kr_query *qry, uint32_t timestamp);
+
+/**
+ * Find the longest prefix zone/xNAME (with OK time+rank), starting at k->*.
+ *
+ * The found type is returned via k->type; the values are returned in el.
+ * \note we use k->type = KNOT_RRTYPE_NS also for the nsec_p result.
+ * \param qry can be NULL (-> gettimeofday(), but you lose the stale-serve hook)
+ * \param only_NS don't consider xNAMEs
+ * \return error code
+ */
+static int closest_NS(struct kr_cache *cache, struct key *k, entry_list_t el,
+			struct kr_query *qry, const bool only_NS, const bool is_DS)
+{
+	/* get the current timestamp */
+	uint32_t timestamp;
+	if (qry) {
+		timestamp = qry->timestamp.tv_sec;
+	} else {
+		struct timeval tv;
+		if (gettimeofday(&tv, NULL)) return kr_error(errno);
+		timestamp = tv.tv_sec;
+	}
+
+	int zlf_len = k->buf[0];
+
+	// LATER(optim): if stype is NS, we check the same value again
+	bool exact_match = true;
+	bool need_zero = true;
+	/* Inspect the NS/xNAME entries, shortening by a label on each iteration. */
+	do {
+		k->buf[0] = zlf_len;
+		knot_db_val_t key = key_exact_type(k, KNOT_RRTYPE_NS);
+		knot_db_val_t val;
+		int ret = cache_op(cache, read, &key, &val, 1);
+		if (ret == -abs(ENOENT)) goto next_label;
+		if (ret) {
+			assert(!ret);
+			if (need_zero) memset(el, 0, sizeof(entry_list_t));
+			return kr_error(ret);
+		}
+
+		/* Check consistency, find any type;
+		 * using `goto` for shortening by another label. */
+		ret = entry_list_parse(val, el);
+		if (ret) {
+			assert(!ret); // do something about it?
+			goto next_label;
+		}
+		need_zero = false;
+		/* More types are possible; try in order.
+		 * For non-fatal failures just "continue;" to try the next type. */
+		/* Now a complication - we need to try EL_DNAME before NSEC*
+		 * (Unfortunately that's not easy to write very nicely.) */
+		if (!only_NS) {
+			const int i = EL_DNAME;
+			ret = check_NS_entry(k, el[i], i, exact_match, is_DS,
+						qry, timestamp);
+			if (ret < 0) goto next_label; else
+			if (!ret) {
+				/* We found our match. */
+				k->zlf_len = zlf_len;
+				return kr_ok();
+			}
+		}
+		const int el_count = only_NS ? EL_NS + 1 : EL_LENGTH;
+		for (int i = 0; i < el_count; ++i) {
+			if (i == EL_DNAME) continue;
+			ret = check_NS_entry(k, el[i], i, exact_match, is_DS,
+						qry, timestamp);
+			if (ret < 0) goto next_label; else
+			if (!ret) {
+				/* We found our match. */
+				k->zlf_len = zlf_len;
+				return kr_ok();
+			}
+		}
+
+	next_label:
+		/* remove one more label */
+		exact_match = false;
+		if (k->zname[0] == 0) {
+			/* We miss root NS in cache, but let's at least assume it exists. */
+			k->type = KNOT_RRTYPE_NS;
+			k->zlf_len = zlf_len;
+			assert(zlf_len == 0);
+			if (need_zero) memset(el, 0, sizeof(entry_list_t));
+			return kr_error(ENOENT);
+		}
+		zlf_len -= (k->zname[0] + 1);
+		k->zname += (k->zname[0] + 1);
+		k->buf[zlf_len + 1] = 0;
+	} while (true);
+}
+
+static int check_NS_entry(struct key *k, const knot_db_val_t entry, const int i,
+			  const bool exact_match, const bool is_DS,
+			  const struct kr_query *qry, uint32_t timestamp)
+{
+	const int ESKIP = ABS(ENOENT);
+	if (!entry.len
+		/* On a zone cut we want DS from the parent zone. */
+		|| (exact_match && is_DS)
+		/* CNAME is interesting only if we
+		 * directly hit the name that was asked.
+		 * Note that we want it even in the DS case. */
+		|| (i == EL_CNAME && !exact_match)
+		/* DNAME is interesting only if we did NOT
+		 * directly hit the name that was asked. */
+		|| (i == EL_DNAME && exact_match)
+	   ) {
+		return ESKIP;
+	}
+
+	uint16_t type;
+	if (i < ENTRY_APEX_NSECS_CNT) {
+		type = KNOT_RRTYPE_NS;
+		int32_t log_new_ttl = -123456789; /* visually recognizable value */
+		const int err = nsec_p_ttl(entry, timestamp, &log_new_ttl);
+		if (err) {
+			VERBOSE_MSG(qry,
+				"=> skipping unfit nsec_p: new TTL %d, error %d\n",
+				(int)log_new_ttl, err);
+			return ESKIP;
+		}
+	} else {
+		type = EL2RRTYPE(i);
+		/* Find the entry for the type, check positivity, TTL */
+		const struct entry_h *eh = entry_h_consistent_E(entry, type);
+		if (!eh) {
+			VERBOSE_MSG(qry, "=> EH not consistent\n");
+			assert(false);
+			return kr_error(EILSEQ);
+		}
+		const int32_t log_new_ttl = get_new_ttl(eh, qry, k->zname, type, timestamp);
+
+		const bool ok = /* Not interested in negative bogus or outdated RRs. */
+			!eh->is_packet && log_new_ttl >= 0
+			/* For NS any kr_rank is accepted, as insecure or even nonauth is OK */
+			&& (type == KNOT_RRTYPE_NS
+			    || eh->rank >= get_lowest_rank(qry, k->zname, type));
+
+		WITH_VERBOSE(qry) { if (!ok) {
+			auto_free char *type_str = kr_rrtype_text(type);
+			const char *packet_str = eh->is_packet ? "packet" : "RR";
+			VERBOSE_MSG(qry,
+				"=> skipping unfit %s %s: rank 0%.2o, new TTL %d\n",
+				type_str, packet_str, eh->rank, (int)log_new_ttl);
+		} }
+		if (!ok) return ESKIP;
+	}
+	k->type = type;
+	return kr_ok();
+}
+
diff --git a/lib/cache/test.integr/cache_minimal_nsec3.rpl b/lib/cache/test.integr/cache_minimal_nsec3.rpl
new file mode 100644
index 0000000..7c4a5cf
--- /dev/null
+++ b/lib/cache/test.integr/cache_minimal_nsec3.rpl
@@ -0,0 +1,4120 @@
+; SPDX-License-Identifier: GPL-3.0-or-later
+	trust-anchor: ". IN DS 20326 8 2 E06D44B80B8F1D39A95C0B0D7C65D08458E880409BBC683457104237C7F8EC8D"
+	val-override-date: 20190625160934
+	stub-addr: 2001:503:ba3e::2:30
+CONFIG_END
+
+SCENARIO_BEGIN Test that minimal NSEC3 range does not trigger agressive cache (workaround for buggy auths, optimization to improve cache hit rate on correct auths using black lies)
+
+; Group's zones:
+;	.
+;	root-servers.net.
+; Server names:
+;	f.root-servers.net.
+;	a.root-servers.net.
+;	j.root-servers.net.
+;	e.root-servers.net.
+;	i.root-servers.net.
+;	d.root-servers.net.
+;	m.root-servers.net.
+;	h.root-servers.net.
+;	c.root-servers.net.
+;	l.root-servers.net.
+;	g.root-servers.net.
+;	b.root-servers.net.
+;	k.root-servers.net.
+RANGE_BEGIN 0 1000
+	ADDRESS 2001:500:2f::f
+	ADDRESS 2001:503:ba3e::2:30
+	ADDRESS 2001:500:12::d0d
+	ADDRESS 202.12.27.33
+	ADDRESS 2001:7fd::1
+	ADDRESS 2001:503:c27::2:30
+	ADDRESS 2001:500:200::b
+	ADDRESS 198.97.190.53
+	ADDRESS 192.58.128.30
+	ADDRESS 198.41.0.4
+	ADDRESS 199.7.91.13
+	ADDRESS 2001:dc3::35
+	ADDRESS 192.36.148.17
+	ADDRESS 192.203.230.10
+	ADDRESS 192.5.5.241
+	ADDRESS 199.9.14.201
+	ADDRESS 193.0.14.129
+	ADDRESS 2001:7fe::53
+	ADDRESS 2001:500:9f::42
+	ADDRESS 2001:500:a8::e
+	ADDRESS 2001:500:2d::d
+	ADDRESS 192.112.36.4
+	ADDRESS 2001:500:2::c
+	ADDRESS 192.33.4.12
+	ADDRESS 199.7.83.42
+	ADDRESS 2001:500:1::53
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+i.root-servers.net. IN AAAA
+SECTION ANSWER
+i.root-servers.net. 3600000 IN AAAA 2001:7fe::53
+SECTION AUTHORITY
+root-servers.net. 3600000 IN NS a.root-servers.net.
+root-servers.net. 3600000 IN NS b.root-servers.net.
+root-servers.net. 3600000 IN NS c.root-servers.net.
+root-servers.net. 3600000 IN NS d.root-servers.net.
+root-servers.net. 3600000 IN NS e.root-servers.net.
+root-servers.net. 3600000 IN NS f.root-servers.net.
+root-servers.net. 3600000 IN NS g.root-servers.net.
+root-servers.net. 3600000 IN NS h.root-servers.net.
+root-servers.net. 3600000 IN NS i.root-servers.net.
+root-servers.net. 3600000 IN NS j.root-servers.net.
+root-servers.net. 3600000 IN NS k.root-servers.net.
+root-servers.net. 3600000 IN NS l.root-servers.net.
+root-servers.net. 3600000 IN NS m.root-servers.net.
+SECTION ADDITIONAL
+a.root-servers.net. 3600000 IN A 198.41.0.4
+a.root-servers.net. 3600000 IN AAAA 2001:503:ba3e::2:30
+b.root-servers.net. 3600000 IN A 199.9.14.201
+b.root-servers.net. 3600000 IN AAAA 2001:500:200::b
+c.root-servers.net. 3600000 IN A 192.33.4.12
+c.root-servers.net. 3600000 IN AAAA 2001:500:2::c
+d.root-servers.net. 3600000 IN A 199.7.91.13
+d.root-servers.net. 3600000 IN AAAA 2001:500:2d::d
+e.root-servers.net. 3600000 IN A 192.203.230.10
+e.root-servers.net. 3600000 IN AAAA 2001:500:a8::e
+f.root-servers.net. 3600000 IN A 192.5.5.241
+f.root-servers.net. 3600000 IN AAAA 2001:500:2f::f
+g.root-servers.net. 3600000 IN A 192.112.36.4
+g.root-servers.net. 3600000 IN AAAA 2001:500:12::d0d
+h.root-servers.net. 3600000 IN A 198.97.190.53
+h.root-servers.net. 3600000 IN AAAA 2001:500:1::53
+i.root-servers.net. 3600000 IN A 192.36.148.17
+j.root-servers.net. 3600000 IN A 192.58.128.30
+j.root-servers.net. 3600000 IN AAAA 2001:503:c27::2:30
+k.root-servers.net. 3600000 IN A 193.0.14.129
+k.root-servers.net. 3600000 IN AAAA 2001:7fd::1
+l.root-servers.net. 3600000 IN A 199.7.83.42
+l.root-servers.net. 3600000 IN AAAA 2001:500:9f::42
+m.root-servers.net. 3600000 IN A 202.12.27.33
+m.root-servers.net. 3600000 IN AAAA 2001:dc3::35
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+g.root-servers.net. IN NS
+SECTION AUTHORITY
+root-servers.net. 3600000 IN SOA a.root-servers.net. nstld.verisign-grs.com. 2019061700 14400 7200 1209600 3600000
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+e.root-servers.net. IN A
+SECTION ANSWER
+e.root-servers.net. 3600000 IN A 192.203.230.10
+SECTION AUTHORITY
+root-servers.net. 3600000 IN NS a.root-servers.net.
+root-servers.net. 3600000 IN NS b.root-servers.net.
+root-servers.net. 3600000 IN NS c.root-servers.net.
+root-servers.net. 3600000 IN NS d.root-servers.net.
+root-servers.net. 3600000 IN NS e.root-servers.net.
+root-servers.net. 3600000 IN NS f.root-servers.net.
+root-servers.net. 3600000 IN NS g.root-servers.net.
+root-servers.net. 3600000 IN NS h.root-servers.net.
+root-servers.net. 3600000 IN NS i.root-servers.net.
+root-servers.net. 3600000 IN NS j.root-servers.net.
+root-servers.net. 3600000 IN NS k.root-servers.net.
+root-servers.net. 3600000 IN NS l.root-servers.net.
+root-servers.net. 3600000 IN NS m.root-servers.net.
+SECTION ADDITIONAL
+a.root-servers.net. 3600000 IN A 198.41.0.4
+a.root-servers.net. 3600000 IN AAAA 2001:503:ba3e::2:30
+b.root-servers.net. 3600000 IN A 199.9.14.201
+b.root-servers.net. 3600000 IN AAAA 2001:500:200::b
+c.root-servers.net. 3600000 IN A 192.33.4.12
+c.root-servers.net. 3600000 IN AAAA 2001:500:2::c
+d.root-servers.net. 3600000 IN A 199.7.91.13
+d.root-servers.net. 3600000 IN AAAA 2001:500:2d::d
+e.root-servers.net. 3600000 IN AAAA 2001:500:a8::e
+f.root-servers.net. 3600000 IN A 192.5.5.241
+f.root-servers.net. 3600000 IN AAAA 2001:500:2f::f
+g.root-servers.net. 3600000 IN A 192.112.36.4
+g.root-servers.net. 3600000 IN AAAA 2001:500:12::d0d
+h.root-servers.net. 3600000 IN A 198.97.190.53
+h.root-servers.net. 3600000 IN AAAA 2001:500:1::53
+i.root-servers.net. 3600000 IN A 192.36.148.17
+i.root-servers.net. 3600000 IN AAAA 2001:7fe::53
+j.root-servers.net. 3600000 IN A 192.58.128.30
+j.root-servers.net. 3600000 IN AAAA 2001:503:c27::2:30
+k.root-servers.net. 3600000 IN A 193.0.14.129
+k.root-servers.net. 3600000 IN AAAA 2001:7fd::1
+l.root-servers.net. 3600000 IN A 199.7.83.42
+l.root-servers.net. 3600000 IN AAAA 2001:500:9f::42
+m.root-servers.net. 3600000 IN A 202.12.27.33
+m.root-servers.net. 3600000 IN AAAA 2001:dc3::35
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+f.root-servers.net. IN NS
+SECTION AUTHORITY
+root-servers.net. 3600000 IN SOA a.root-servers.net. nstld.verisign-grs.com. 2019061700 14400 7200 1209600 3600000
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+i.root-servers.net. IN A
+SECTION ANSWER
+i.root-servers.net. 3600000 IN A 192.36.148.17
+SECTION AUTHORITY
+root-servers.net. 3600000 IN NS a.root-servers.net.
+root-servers.net. 3600000 IN NS b.root-servers.net.
+root-servers.net. 3600000 IN NS c.root-servers.net.
+root-servers.net. 3600000 IN NS d.root-servers.net.
+root-servers.net. 3600000 IN NS e.root-servers.net.
+root-servers.net. 3600000 IN NS f.root-servers.net.
+root-servers.net. 3600000 IN NS g.root-servers.net.
+root-servers.net. 3600000 IN NS h.root-servers.net.
+root-servers.net. 3600000 IN NS i.root-servers.net.
+root-servers.net. 3600000 IN NS j.root-servers.net.
+root-servers.net. 3600000 IN NS k.root-servers.net.
+root-servers.net. 3600000 IN NS l.root-servers.net.
+root-servers.net. 3600000 IN NS m.root-servers.net.
+SECTION ADDITIONAL
+a.root-servers.net. 3600000 IN A 198.41.0.4
+a.root-servers.net. 3600000 IN AAAA 2001:503:ba3e::2:30
+b.root-servers.net. 3600000 IN A 199.9.14.201
+b.root-servers.net. 3600000 IN AAAA 2001:500:200::b
+c.root-servers.net. 3600000 IN A 192.33.4.12
+c.root-servers.net. 3600000 IN AAAA 2001:500:2::c
+d.root-servers.net. 3600000 IN A 199.7.91.13
+d.root-servers.net. 3600000 IN AAAA 2001:500:2d::d
+e.root-servers.net. 3600000 IN A 192.203.230.10
+e.root-servers.net. 3600000 IN AAAA 2001:500:a8::e
+f.root-servers.net. 3600000 IN A 192.5.5.241
+f.root-servers.net. 3600000 IN AAAA 2001:500:2f::f
+g.root-servers.net. 3600000 IN A 192.112.36.4
+g.root-servers.net. 3600000 IN AAAA 2001:500:12::d0d
+h.root-servers.net. 3600000 IN A 198.97.190.53
+h.root-servers.net. 3600000 IN AAAA 2001:500:1::53
+i.root-servers.net. 3600000 IN AAAA 2001:7fe::53
+j.root-servers.net. 3600000 IN A 192.58.128.30
+j.root-servers.net. 3600000 IN AAAA 2001:503:c27::2:30
+k.root-servers.net. 3600000 IN A 193.0.14.129
+k.root-servers.net. 3600000 IN AAAA 2001:7fd::1
+l.root-servers.net. 3600000 IN A 199.7.83.42
+l.root-servers.net. 3600000 IN AAAA 2001:500:9f::42
+m.root-servers.net. 3600000 IN A 202.12.27.33
+m.root-servers.net. 3600000 IN AAAA 2001:dc3::35
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+c.root-servers.net. IN NS
+SECTION AUTHORITY
+root-servers.net. 3600000 IN SOA a.root-servers.net. nstld.verisign-grs.com. 2019061700 14400 7200 1209600 3600000
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+root-servers.net. IN DS
+SECTION AUTHORITY
+root-servers.net. 3600000 IN SOA a.root-servers.net. nstld.verisign-grs.com. 2019061700 14400 7200 1209600 3600000
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+c.root-servers.net. IN A
+SECTION ANSWER
+c.root-servers.net. 3600000 IN A 192.33.4.12
+SECTION AUTHORITY
+root-servers.net. 3600000 IN NS a.root-servers.net.
+root-servers.net. 3600000 IN NS b.root-servers.net.
+root-servers.net. 3600000 IN NS c.root-servers.net.
+root-servers.net. 3600000 IN NS d.root-servers.net.
+root-servers.net. 3600000 IN NS e.root-servers.net.
+root-servers.net. 3600000 IN NS f.root-servers.net.
+root-servers.net. 3600000 IN NS g.root-servers.net.
+root-servers.net. 3600000 IN NS h.root-servers.net.
+root-servers.net. 3600000 IN NS i.root-servers.net.
+root-servers.net. 3600000 IN NS j.root-servers.net.
+root-servers.net. 3600000 IN NS k.root-servers.net.
+root-servers.net. 3600000 IN NS l.root-servers.net.
+root-servers.net. 3600000 IN NS m.root-servers.net.
+SECTION ADDITIONAL
+a.root-servers.net. 3600000 IN A 198.41.0.4
+a.root-servers.net. 3600000 IN AAAA 2001:503:ba3e::2:30
+b.root-servers.net. 3600000 IN A 199.9.14.201
+b.root-servers.net. 3600000 IN AAAA 2001:500:200::b
+c.root-servers.net. 3600000 IN AAAA 2001:500:2::c
+d.root-servers.net. 3600000 IN A 199.7.91.13
+d.root-servers.net. 3600000 IN AAAA 2001:500:2d::d
+e.root-servers.net. 3600000 IN A 192.203.230.10
+e.root-servers.net. 3600000 IN AAAA 2001:500:a8::e
+f.root-servers.net. 3600000 IN A 192.5.5.241
+f.root-servers.net. 3600000 IN AAAA 2001:500:2f::f
+g.root-servers.net. 3600000 IN A 192.112.36.4
+g.root-servers.net. 3600000 IN AAAA 2001:500:12::d0d
+h.root-servers.net. 3600000 IN A 198.97.190.53
+h.root-servers.net. 3600000 IN AAAA 2001:500:1::53
+i.root-servers.net. 3600000 IN A 192.36.148.17
+i.root-servers.net. 3600000 IN AAAA 2001:7fe::53
+j.root-servers.net. 3600000 IN A 192.58.128.30
+j.root-servers.net. 3600000 IN AAAA 2001:503:c27::2:30
+k.root-servers.net. 3600000 IN A 193.0.14.129
+k.root-servers.net. 3600000 IN AAAA 2001:7fd::1
+l.root-servers.net. 3600000 IN A 199.7.83.42
+l.root-servers.net. 3600000 IN AAAA 2001:500:9f::42
+m.root-servers.net. 3600000 IN A 202.12.27.33
+m.root-servers.net. 3600000 IN AAAA 2001:dc3::35
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+d.root-servers.net. IN A
+SECTION ANSWER
+d.root-servers.net. 3600000 IN A 199.7.91.13
+SECTION AUTHORITY
+root-servers.net. 3600000 IN NS a.root-servers.net.
+root-servers.net. 3600000 IN NS b.root-servers.net.
+root-servers.net. 3600000 IN NS c.root-servers.net.
+root-servers.net. 3600000 IN NS d.root-servers.net.
+root-servers.net. 3600000 IN NS e.root-servers.net.
+root-servers.net. 3600000 IN NS f.root-servers.net.
+root-servers.net. 3600000 IN NS g.root-servers.net.
+root-servers.net. 3600000 IN NS h.root-servers.net.
+root-servers.net. 3600000 IN NS i.root-servers.net.
+root-servers.net. 3600000 IN NS j.root-servers.net.
+root-servers.net. 3600000 IN NS k.root-servers.net.
+root-servers.net. 3600000 IN NS l.root-servers.net.
+root-servers.net. 3600000 IN NS m.root-servers.net.
+SECTION ADDITIONAL
+a.root-servers.net. 3600000 IN A 198.41.0.4
+a.root-servers.net. 3600000 IN AAAA 2001:503:ba3e::2:30
+b.root-servers.net. 3600000 IN A 199.9.14.201
+b.root-servers.net. 3600000 IN AAAA 2001:500:200::b
+c.root-servers.net. 3600000 IN A 192.33.4.12
+c.root-servers.net. 3600000 IN AAAA 2001:500:2::c
+d.root-servers.net. 3600000 IN AAAA 2001:500:2d::d
+e.root-servers.net. 3600000 IN A 192.203.230.10
+e.root-servers.net. 3600000 IN AAAA 2001:500:a8::e
+f.root-servers.net. 3600000 IN A 192.5.5.241
+f.root-servers.net. 3600000 IN AAAA 2001:500:2f::f
+g.root-servers.net. 3600000 IN A 192.112.36.4
+g.root-servers.net. 3600000 IN AAAA 2001:500:12::d0d
+h.root-servers.net. 3600000 IN A 198.97.190.53
+h.root-servers.net. 3600000 IN AAAA 2001:500:1::53
+i.root-servers.net. 3600000 IN A 192.36.148.17
+i.root-servers.net. 3600000 IN AAAA 2001:7fe::53
+j.root-servers.net. 3600000 IN A 192.58.128.30
+j.root-servers.net. 3600000 IN AAAA 2001:503:c27::2:30
+k.root-servers.net. 3600000 IN A 193.0.14.129
+k.root-servers.net. 3600000 IN AAAA 2001:7fd::1
+l.root-servers.net. 3600000 IN A 199.7.83.42
+l.root-servers.net. 3600000 IN AAAA 2001:500:9f::42
+m.root-servers.net. 3600000 IN A 202.12.27.33
+m.root-servers.net. 3600000 IN AAAA 2001:dc3::35
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+f.root-servers.net. IN AAAA
+SECTION ANSWER
+f.root-servers.net. 3600000 IN AAAA 2001:500:2f::f
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+. IN NS
+SECTION ANSWER
+. 518400 IN NS a.root-servers.net.
+. 518400 IN NS b.root-servers.net.
+. 518400 IN NS c.root-servers.net.
+. 518400 IN NS d.root-servers.net.
+. 518400 IN NS e.root-servers.net.
+. 518400 IN NS f.root-servers.net.
+. 518400 IN NS g.root-servers.net.
+. 518400 IN NS h.root-servers.net.
+. 518400 IN NS i.root-servers.net.
+. 518400 IN NS j.root-servers.net.
+. 518400 IN NS k.root-servers.net.
+. 518400 IN NS l.root-servers.net.
+. 518400 IN NS m.root-servers.net.
+. 518400 IN RRSIG NS 8 0 518400 20190708050000 20190625040000 25266 . IwbmJVqFUjJz5WwRbYqOWejRck85QWW8 eIGID2J+Qhw89iUDDz2lgvysed4WQfks 8Y2XZu79T0+RJF+mj1UUiE+Y6RdOmFDU Qx3ovGkYwOXcr1anreBD+Wn5tv1WW6El NbKf40pXdtDX6Ad1qx6hCHHR4hieQPww psNHmrGDg+Eog+VqYjwwRj9EaYEms5dU PRJmiHiACe85DZMCjxl6f+kp7ZXyFD/L coLi7QzXiRWYOPHhWKk3pqYGD1j7I7YB Oq7UujK+jPscWCDuArGmZwlhAtAPaPLe 5TZHIGE39c6eYpuXwSXZ1EPM545/9WsI HihzUQ75ltuiPXwjv0OpQg==
+SECTION ADDITIONAL
+a.root-servers.net. 3600000 IN A 198.41.0.4
+a.root-servers.net. 3600000 IN AAAA 2001:503:ba3e::2:30
+b.root-servers.net. 3600000 IN A 199.9.14.201
+b.root-servers.net. 3600000 IN AAAA 2001:500:200::b
+c.root-servers.net. 3600000 IN A 192.33.4.12
+c.root-servers.net. 3600000 IN AAAA 2001:500:2::c
+d.root-servers.net. 3600000 IN A 199.7.91.13
+d.root-servers.net. 3600000 IN AAAA 2001:500:2d::d
+e.root-servers.net. 3600000 IN A 192.203.230.10
+e.root-servers.net. 3600000 IN AAAA 2001:500:a8::e
+f.root-servers.net. 3600000 IN A 192.5.5.241
+f.root-servers.net. 3600000 IN AAAA 2001:500:2f::f
+g.root-servers.net. 3600000 IN A 192.112.36.4
+g.root-servers.net. 3600000 IN AAAA 2001:500:12::d0d
+h.root-servers.net. 3600000 IN A 198.97.190.53
+h.root-servers.net. 3600000 IN AAAA 2001:500:1::53
+i.root-servers.net. 3600000 IN A 192.36.148.17
+i.root-servers.net. 3600000 IN AAAA 2001:7fe::53
+j.root-servers.net. 3600000 IN A 192.58.128.30
+j.root-servers.net. 3600000 IN AAAA 2001:503:c27::2:30
+k.root-servers.net. 3600000 IN A 193.0.14.129
+k.root-servers.net. 3600000 IN AAAA 2001:7fd::1
+l.root-servers.net. 3600000 IN A 199.7.83.42
+l.root-servers.net. 3600000 IN AAAA 2001:500:9f::42
+m.root-servers.net. 3600000 IN A 202.12.27.33
+m.root-servers.net. 3600000 IN AAAA 2001:dc3::35
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+j.root-servers.net. IN NS
+SECTION AUTHORITY
+root-servers.net. 3600000 IN SOA a.root-servers.net. nstld.verisign-grs.com. 2019061700 14400 7200 1209600 3600000
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+a.root-servers.net. IN A
+SECTION ANSWER
+a.root-servers.net. 3600000 IN A 198.41.0.4
+SECTION AUTHORITY
+root-servers.net. 3600000 IN NS a.root-servers.net.
+root-servers.net. 3600000 IN NS b.root-servers.net.
+root-servers.net. 3600000 IN NS c.root-servers.net.
+root-servers.net. 3600000 IN NS d.root-servers.net.
+root-servers.net. 3600000 IN NS e.root-servers.net.
+root-servers.net. 3600000 IN NS f.root-servers.net.
+root-servers.net. 3600000 IN NS g.root-servers.net.
+root-servers.net. 3600000 IN NS h.root-servers.net.
+root-servers.net. 3600000 IN NS i.root-servers.net.
+root-servers.net. 3600000 IN NS j.root-servers.net.
+root-servers.net. 3600000 IN NS k.root-servers.net.
+root-servers.net. 3600000 IN NS l.root-servers.net.
+root-servers.net. 3600000 IN NS m.root-servers.net.
+SECTION ADDITIONAL
+a.root-servers.net. 3600000 IN AAAA 2001:503:ba3e::2:30
+b.root-servers.net. 3600000 IN A 199.9.14.201
+b.root-servers.net. 3600000 IN AAAA 2001:500:200::b
+c.root-servers.net. 3600000 IN A 192.33.4.12
+c.root-servers.net. 3600000 IN AAAA 2001:500:2::c
+d.root-servers.net. 3600000 IN A 199.7.91.13
+d.root-servers.net. 3600000 IN AAAA 2001:500:2d::d
+e.root-servers.net. 3600000 IN A 192.203.230.10
+e.root-servers.net. 3600000 IN AAAA 2001:500:a8::e
+f.root-servers.net. 3600000 IN A 192.5.5.241
+f.root-servers.net. 3600000 IN AAAA 2001:500:2f::f
+g.root-servers.net. 3600000 IN A 192.112.36.4
+g.root-servers.net. 3600000 IN AAAA 2001:500:12::d0d
+h.root-servers.net. 3600000 IN A 198.97.190.53
+h.root-servers.net. 3600000 IN AAAA 2001:500:1::53
+i.root-servers.net. 3600000 IN A 192.36.148.17
+i.root-servers.net. 3600000 IN AAAA 2001:7fe::53
+j.root-servers.net. 3600000 IN A 192.58.128.30
+j.root-servers.net. 3600000 IN AAAA 2001:503:c27::2:30
+k.root-servers.net. 3600000 IN A 193.0.14.129
+k.root-servers.net. 3600000 IN AAAA 2001:7fd::1
+l.root-servers.net. 3600000 IN A 199.7.83.42
+l.root-servers.net. 3600000 IN AAAA 2001:500:9f::42
+m.root-servers.net. 3600000 IN A 202.12.27.33
+m.root-servers.net. 3600000 IN AAAA 2001:dc3::35
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+h.root-servers.net. IN NS
+SECTION AUTHORITY
+root-servers.net. 3600000 IN SOA a.root-servers.net. nstld.verisign-grs.com. 2019061700 14400 7200 1209600 3600000
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+g.root-servers.net. IN A
+SECTION ANSWER
+g.root-servers.net. 3600000 IN A 192.112.36.4
+SECTION AUTHORITY
+root-servers.net. 3600000 IN NS a.root-servers.net.
+root-servers.net. 3600000 IN NS b.root-servers.net.
+root-servers.net. 3600000 IN NS c.root-servers.net.
+root-servers.net. 3600000 IN NS d.root-servers.net.
+root-servers.net. 3600000 IN NS e.root-servers.net.
+root-servers.net. 3600000 IN NS f.root-servers.net.
+root-servers.net. 3600000 IN NS g.root-servers.net.
+root-servers.net. 3600000 IN NS h.root-servers.net.
+root-servers.net. 3600000 IN NS i.root-servers.net.
+root-servers.net. 3600000 IN NS j.root-servers.net.
+root-servers.net. 3600000 IN NS k.root-servers.net.
+root-servers.net. 3600000 IN NS l.root-servers.net.
+root-servers.net. 3600000 IN NS m.root-servers.net.
+SECTION ADDITIONAL
+a.root-servers.net. 3600000 IN A 198.41.0.4
+a.root-servers.net. 3600000 IN AAAA 2001:503:ba3e::2:30
+b.root-servers.net. 3600000 IN A 199.9.14.201
+b.root-servers.net. 3600000 IN AAAA 2001:500:200::b
+c.root-servers.net. 3600000 IN A 192.33.4.12
+c.root-servers.net. 3600000 IN AAAA 2001:500:2::c
+d.root-servers.net. 3600000 IN A 199.7.91.13
+d.root-servers.net. 3600000 IN AAAA 2001:500:2d::d
+e.root-servers.net. 3600000 IN A 192.203.230.10
+e.root-servers.net. 3600000 IN AAAA 2001:500:a8::e
+f.root-servers.net. 3600000 IN A 192.5.5.241
+f.root-servers.net. 3600000 IN AAAA 2001:500:2f::f
+g.root-servers.net. 3600000 IN AAAA 2001:500:12::d0d
+h.root-servers.net. 3600000 IN A 198.97.190.53
+h.root-servers.net. 3600000 IN AAAA 2001:500:1::53
+i.root-servers.net. 3600000 IN A 192.36.148.17
+i.root-servers.net. 3600000 IN AAAA 2001:7fe::53
+j.root-servers.net. 3600000 IN A 192.58.128.30
+j.root-servers.net. 3600000 IN AAAA 2001:503:c27::2:30
+k.root-servers.net. 3600000 IN A 193.0.14.129
+k.root-servers.net. 3600000 IN AAAA 2001:7fd::1
+l.root-servers.net. 3600000 IN A 199.7.83.42
+l.root-servers.net. 3600000 IN AAAA 2001:500:9f::42
+m.root-servers.net. 3600000 IN A 202.12.27.33
+m.root-servers.net. 3600000 IN AAAA 2001:dc3::35
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+k.root-servers.net. IN A
+SECTION ANSWER
+k.root-servers.net. 3600000 IN A 193.0.14.129
+SECTION AUTHORITY
+root-servers.net. 3600000 IN NS a.root-servers.net.
+root-servers.net. 3600000 IN NS b.root-servers.net.
+root-servers.net. 3600000 IN NS c.root-servers.net.
+root-servers.net. 3600000 IN NS d.root-servers.net.
+root-servers.net. 3600000 IN NS e.root-servers.net.
+root-servers.net. 3600000 IN NS f.root-servers.net.
+root-servers.net. 3600000 IN NS g.root-servers.net.
+root-servers.net. 3600000 IN NS h.root-servers.net.
+root-servers.net. 3600000 IN NS i.root-servers.net.
+root-servers.net. 3600000 IN NS j.root-servers.net.
+root-servers.net. 3600000 IN NS k.root-servers.net.
+root-servers.net. 3600000 IN NS l.root-servers.net.
+root-servers.net. 3600000 IN NS m.root-servers.net.
+SECTION ADDITIONAL
+a.root-servers.net. 3600000 IN A 198.41.0.4
+a.root-servers.net. 3600000 IN AAAA 2001:503:ba3e::2:30
+b.root-servers.net. 3600000 IN A 199.9.14.201
+b.root-servers.net. 3600000 IN AAAA 2001:500:200::b
+c.root-servers.net. 3600000 IN A 192.33.4.12
+c.root-servers.net. 3600000 IN AAAA 2001:500:2::c
+d.root-servers.net. 3600000 IN A 199.7.91.13
+d.root-servers.net. 3600000 IN AAAA 2001:500:2d::d
+e.root-servers.net. 3600000 IN A 192.203.230.10
+e.root-servers.net. 3600000 IN AAAA 2001:500:a8::e
+f.root-servers.net. 3600000 IN A 192.5.5.241
+f.root-servers.net. 3600000 IN AAAA 2001:500:2f::f
+g.root-servers.net. 3600000 IN A 192.112.36.4
+g.root-servers.net. 3600000 IN AAAA 2001:500:12::d0d
+h.root-servers.net. 3600000 IN A 198.97.190.53
+h.root-servers.net. 3600000 IN AAAA 2001:500:1::53
+i.root-servers.net. 3600000 IN A 192.36.148.17
+i.root-servers.net. 3600000 IN AAAA 2001:7fe::53
+j.root-servers.net. 3600000 IN A 192.58.128.30
+j.root-servers.net. 3600000 IN AAAA 2001:503:c27::2:30
+k.root-servers.net. 3600000 IN AAAA 2001:7fd::1
+l.root-servers.net. 3600000 IN A 199.7.83.42
+l.root-servers.net. 3600000 IN AAAA 2001:500:9f::42
+m.root-servers.net. 3600000 IN A 202.12.27.33
+m.root-servers.net. 3600000 IN AAAA 2001:dc3::35
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+m.root-servers.net. IN AAAA
+SECTION ANSWER
+m.root-servers.net. 3600000 IN AAAA 2001:dc3::35
+SECTION AUTHORITY
+root-servers.net. 3600000 IN NS a.root-servers.net.
+root-servers.net. 3600000 IN NS b.root-servers.net.
+root-servers.net. 3600000 IN NS c.root-servers.net.
+root-servers.net. 3600000 IN NS d.root-servers.net.
+root-servers.net. 3600000 IN NS e.root-servers.net.
+root-servers.net. 3600000 IN NS f.root-servers.net.
+root-servers.net. 3600000 IN NS g.root-servers.net.
+root-servers.net. 3600000 IN NS h.root-servers.net.
+root-servers.net. 3600000 IN NS i.root-servers.net.
+root-servers.net. 3600000 IN NS j.root-servers.net.
+root-servers.net. 3600000 IN NS k.root-servers.net.
+root-servers.net. 3600000 IN NS l.root-servers.net.
+root-servers.net. 3600000 IN NS m.root-servers.net.
+SECTION ADDITIONAL
+a.root-servers.net. 3600000 IN A 198.41.0.4
+a.root-servers.net. 3600000 IN AAAA 2001:503:ba3e::2:30
+b.root-servers.net. 3600000 IN A 199.9.14.201
+b.root-servers.net. 3600000 IN AAAA 2001:500:200::b
+c.root-servers.net. 3600000 IN A 192.33.4.12
+c.root-servers.net. 3600000 IN AAAA 2001:500:2::c
+d.root-servers.net. 3600000 IN A 199.7.91.13
+d.root-servers.net. 3600000 IN AAAA 2001:500:2d::d
+e.root-servers.net. 3600000 IN A 192.203.230.10
+e.root-servers.net. 3600000 IN AAAA 2001:500:a8::e
+f.root-servers.net. 3600000 IN A 192.5.5.241
+f.root-servers.net. 3600000 IN AAAA 2001:500:2f::f
+g.root-servers.net. 3600000 IN A 192.112.36.4
+g.root-servers.net. 3600000 IN AAAA 2001:500:12::d0d
+h.root-servers.net. 3600000 IN A 198.97.190.53
+h.root-servers.net. 3600000 IN AAAA 2001:500:1::53
+i.root-servers.net. 3600000 IN A 192.36.148.17
+i.root-servers.net. 3600000 IN AAAA 2001:7fe::53
+j.root-servers.net. 3600000 IN A 192.58.128.30
+j.root-servers.net. 3600000 IN AAAA 2001:503:c27::2:30
+k.root-servers.net. 3600000 IN A 193.0.14.129
+k.root-servers.net. 3600000 IN AAAA 2001:7fd::1
+l.root-servers.net. 3600000 IN A 199.7.83.42
+l.root-servers.net. 3600000 IN AAAA 2001:500:9f::42
+m.root-servers.net. 3600000 IN A 202.12.27.33
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+. IN DNSKEY
+SECTION ANSWER
+. 172800 IN DNSKEY 256 3 8 AwEAAcTQyaIe6nt3xSPOG2L/YfwBkOVT JN6mlnZ249O5Rtt3ZSRQHxQSW61AODYw 6bvgxrrGq8eeOuenFjcSYgNAMcBYoEYY mKDW6e9EryW4ZaT/MCq+8Am06oR40xAA 3fClOM6QjRcT85tP41Go946AicBGP8XO P/Aj1aI/oPRGzRnboUPUok/AzTNnW5np BU69+BuiIwYE7mQOiNBFePyvjQBdoiuY bmuD3Py0IyjlBxzZUXbqLsRL9gYFkCqe TY29Ik7usuzMTa+JRSLz6KGS5RSJ7CTS MjZg8aNaUbN2dvGhakJPh92HnLvMA3Te fFgbKJphFNPA3BWSKLZ02cRWXqM=
+. 172800 IN DNSKEY 256 3 8 AwEAAeVDC34GZILwsQJy97K2Fst4P3XY ZrXLyrkausYzSqEjSUulgh+iLgHg0y7F IF890+sIjXsk7KLJUmCOWfYWPorNKEOK Lk5Zx/4M6D3IHZE3O3m/Eahrc28qQzmT LxiMZAW65MvR2UO3LxVtYOPBEBiDgAQD 47x2JLsJYtavCzNL5WiUk59OgvHmDqmc C7VXYBhK8V8Tic089XJgExGeplKWUt9y yc31ra1swJX51XsOaQz17+vyLVH8AZP2 6KvKFiZeoRbaq6vl+hc8HQnI2ug5rA2z oz3MsSQBvP1f/HvqsWxLqwXXKyDD1QM6 39U+XzVB8CYigyscRP22QCnwKIU=
+. 172800 IN DNSKEY 257 3 8 AwEAAaz/tAm8yTn4Mfeh5eyI96WSVexT BAvkMgJzkKTOiW1vkIbzxeF3+/4RgWOq 7HrxRixHlFlExOLAJr5emLvN7SWXgnLh 4+B5xQlNVz8Og8kvArMtNROxVQuCaSnI DdD5LKyWbRd2n9WGe2R8PzgCmr3EgVLr jyBxWezF0jLHwVN8efS3rCj/EWgvIWgb 9tarpVUDK/b58Da+sqqls3eNbuv7pr+e oZG+SrDK6nWeL3c6H5Apxz7LjVc1uTId sIXxuOLYA4/ilBmSVIzuDWfdRUfhHdY6 +cn8HFRm+2hM8AnXGXws9555KrUB5qih ylGa8subX2Nn6UwNR1AkUTV74bU=
+. 172800 IN RRSIG DNSKEY 8 0 172800 20190711000000 20190620000000 20326 . LeNUOIxGGe+xAKxr13YIXNqMAxVH7RuD XQyVclUuxA9aENp0+yYkeIL+/lkTteEh dHXNVZqYch8QrvcsuCpDN2gKx5D5M04g KAjR5ywgvEdsZHr9DhjCZ3uvXKvbPsi6 14QpjYCxxvtq/ZZE6dhm59K3N3T8Mhm5 l36b6w+fR1F3Kc+eeJqy2ZjVxNe9CClE 4Qy6q78Yu6rS1vZkuzG1l2AT9Gko72St WbdsU2Ry9fBk+uCJOLxej37z5Rfi5EAz FcnfwQYryqCRt2go9PuD0/AulqG8wmTV z23tnwnaxowkYKxFH2yE0d7pDiFjvOyU HdGPXYwl/+GDmjrQsN6JPQ==
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+b.root-servers.net. IN NS
+SECTION AUTHORITY
+root-servers.net. 3600000 IN SOA a.root-servers.net. nstld.verisign-grs.com. 2019061700 14400 7200 1209600 3600000
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+k.root-servers.net. IN NS
+SECTION AUTHORITY
+root-servers.net. 3600000 IN SOA a.root-servers.net. nstld.verisign-grs.com. 2019061700 14400 7200 1209600 3600000
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+. IN DS
+SECTION AUTHORITY
+. 86400 IN NSEC aaa. NS SOA RRSIG NSEC DNSKEY
+. 86400 IN RRSIG NSEC 8 0 86400 20190708050000 20190625040000 25266 . fAYegvNXOW8j+x++y5EWtNQlie56/WO+ w6PlDWJ87oZPgUJuYPxqCIpoKJttfUBR o1nOzZaUlxQeOE0Daep/fnlo8OtAfauK w5J+l5rZqcaM6C9MA7cB7ZswPVd1p609 rPqgGoxSvuNuX/iFPBqPQhRw5JyiVuwF Q4PSB3Etq85BXUEhlpfcQAt6z3scHlLa ARoZoea3/u9z/xuB+296IgZHOQkp3WJL zJivnrQFisO7vQ7o01t0x6WxtskBwbf3 GXwHg/2DbHY/7QJ4hVWO0/L+tdeJciTM 92+RC/U7GkUPDb0rvfOfntB2MKz0rZhU g5m+qJOJYpG8HGN69f4dyQ==
+. 86400 IN RRSIG SOA 8 0 86400 20190708050000 20190625040000 25266 . kYJsFlFDsY3FO94BM5DRROo34/8EZODz iOXejYh397rIJqr5bjx315WJabGoAf3p gtQ5U6QXDJnrKnuZYK/4b+mYyef722if vfNdKclJxKp5vwdDGKLEu7Z2Ey09K4WD MPeyemaIIlbDw3F7lYzz0ZiZubagtrZu OeD2CUOJO4qauzUpGtXf4cx0r+aQJkPq 4eXQyBQ4gg6Mdh4iBNgjGhYB9SLFNMtb eRMNpJG2ifhjP+pNWd27+TGHOhHTu082 osz2lNYKibuMoEfQeHNlINGIU+8oTa/K 3O7IlOAp1APvDmbKnLgy9FFf+6yCMo5y r+A0RVMZheQA3iEXBGug+g==
+. 86400 IN SOA a.root-servers.net. nstld.verisign-grs.com. 2019062500 1800 900 604800 86400
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+c.root-servers.net. IN AAAA
+SECTION ANSWER
+c.root-servers.net. 3600000 IN AAAA 2001:500:2::c
+SECTION AUTHORITY
+root-servers.net. 3600000 IN NS a.root-servers.net.
+root-servers.net. 3600000 IN NS b.root-servers.net.
+root-servers.net. 3600000 IN NS c.root-servers.net.
+root-servers.net. 3600000 IN NS d.root-servers.net.
+root-servers.net. 3600000 IN NS e.root-servers.net.
+root-servers.net. 3600000 IN NS f.root-servers.net.
+root-servers.net. 3600000 IN NS g.root-servers.net.
+root-servers.net. 3600000 IN NS h.root-servers.net.
+root-servers.net. 3600000 IN NS i.root-servers.net.
+root-servers.net. 3600000 IN NS j.root-servers.net.
+root-servers.net. 3600000 IN NS k.root-servers.net.
+root-servers.net. 3600000 IN NS l.root-servers.net.
+root-servers.net. 3600000 IN NS m.root-servers.net.
+SECTION ADDITIONAL
+a.root-servers.net. 3600000 IN A 198.41.0.4
+a.root-servers.net. 3600000 IN AAAA 2001:503:ba3e::2:30
+b.root-servers.net. 3600000 IN A 199.9.14.201
+b.root-servers.net. 3600000 IN AAAA 2001:500:200::b
+c.root-servers.net. 3600000 IN A 192.33.4.12
+d.root-servers.net. 3600000 IN A 199.7.91.13
+d.root-servers.net. 3600000 IN AAAA 2001:500:2d::d
+e.root-servers.net. 3600000 IN A 192.203.230.10
+e.root-servers.net. 3600000 IN AAAA 2001:500:a8::e
+f.root-servers.net. 3600000 IN A 192.5.5.241
+f.root-servers.net. 3600000 IN AAAA 2001:500:2f::f
+g.root-servers.net. 3600000 IN A 192.112.36.4
+g.root-servers.net. 3600000 IN AAAA 2001:500:12::d0d
+h.root-servers.net. 3600000 IN A 198.97.190.53
+h.root-servers.net. 3600000 IN AAAA 2001:500:1::53
+i.root-servers.net. 3600000 IN A 192.36.148.17
+i.root-servers.net. 3600000 IN AAAA 2001:7fe::53
+j.root-servers.net. 3600000 IN A 192.58.128.30
+j.root-servers.net. 3600000 IN AAAA 2001:503:c27::2:30
+k.root-servers.net. 3600000 IN A 193.0.14.129
+k.root-servers.net. 3600000 IN AAAA 2001:7fd::1
+l.root-servers.net. 3600000 IN A 199.7.83.42
+l.root-servers.net. 3600000 IN AAAA 2001:500:9f::42
+m.root-servers.net. 3600000 IN A 202.12.27.33
+m.root-servers.net. 3600000 IN AAAA 2001:dc3::35
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+l.root-servers.net. IN NS
+SECTION AUTHORITY
+root-servers.net. 3600000 IN SOA a.root-servers.net. nstld.verisign-grs.com. 2019061700 14400 7200 1209600 3600000
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+b.root-servers.net. IN A
+SECTION ANSWER
+b.root-servers.net. 3600000 IN A 199.9.14.201
+SECTION AUTHORITY
+root-servers.net. 3600000 IN NS a.root-servers.net.
+root-servers.net. 3600000 IN NS b.root-servers.net.
+root-servers.net. 3600000 IN NS c.root-servers.net.
+root-servers.net. 3600000 IN NS d.root-servers.net.
+root-servers.net. 3600000 IN NS e.root-servers.net.
+root-servers.net. 3600000 IN NS f.root-servers.net.
+root-servers.net. 3600000 IN NS g.root-servers.net.
+root-servers.net. 3600000 IN NS h.root-servers.net.
+root-servers.net. 3600000 IN NS i.root-servers.net.
+root-servers.net. 3600000 IN NS j.root-servers.net.
+root-servers.net. 3600000 IN NS k.root-servers.net.
+root-servers.net. 3600000 IN NS l.root-servers.net.
+root-servers.net. 3600000 IN NS m.root-servers.net.
+SECTION ADDITIONAL
+a.root-servers.net. 3600000 IN A 198.41.0.4
+a.root-servers.net. 3600000 IN AAAA 2001:503:ba3e::2:30
+b.root-servers.net. 3600000 IN AAAA 2001:500:200::b
+c.root-servers.net. 3600000 IN A 192.33.4.12
+c.root-servers.net. 3600000 IN AAAA 2001:500:2::c
+d.root-servers.net. 3600000 IN A 199.7.91.13
+d.root-servers.net. 3600000 IN AAAA 2001:500:2d::d
+e.root-servers.net. 3600000 IN A 192.203.230.10
+e.root-servers.net. 3600000 IN AAAA 2001:500:a8::e
+f.root-servers.net. 3600000 IN A 192.5.5.241
+f.root-servers.net. 3600000 IN AAAA 2001:500:2f::f
+g.root-servers.net. 3600000 IN A 192.112.36.4
+g.root-servers.net. 3600000 IN AAAA 2001:500:12::d0d
+h.root-servers.net. 3600000 IN A 198.97.190.53
+h.root-servers.net. 3600000 IN AAAA 2001:500:1::53
+i.root-servers.net. 3600000 IN A 192.36.148.17
+i.root-servers.net. 3600000 IN AAAA 2001:7fe::53
+j.root-servers.net. 3600000 IN A 192.58.128.30
+j.root-servers.net. 3600000 IN AAAA 2001:503:c27::2:30
+k.root-servers.net. 3600000 IN A 193.0.14.129
+k.root-servers.net. 3600000 IN AAAA 2001:7fd::1
+l.root-servers.net. 3600000 IN A 199.7.83.42
+l.root-servers.net. 3600000 IN AAAA 2001:500:9f::42
+m.root-servers.net. 3600000 IN A 202.12.27.33
+m.root-servers.net. 3600000 IN AAAA 2001:dc3::35
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+m.root-servers.net. IN NS
+SECTION AUTHORITY
+root-servers.net. 3600000 IN SOA a.root-servers.net. nstld.verisign-grs.com. 2019061700 14400 7200 1209600 3600000
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR RD NOERROR
+SECTION QUESTION
+csas.cz. IN DS
+SECTION AUTHORITY
+cz. 172800 IN NS a.ns.nic.cz.
+cz. 172800 IN NS b.ns.nic.cz.
+cz. 172800 IN NS c.ns.nic.cz.
+cz. 172800 IN NS d.ns.nic.cz.
+cz. 86400 IN DS 20237 13 2 cff0f3ecdbc529c1f0031ba1840bfb835853b9209ed1e508fff48451d7b778e2
+cz. 86400 IN RRSIG DS 8 1 86400 20190708050000 20190625040000 25266 . r7Lxqu4C80oW46tP7BNfJWrXs2K5YEqn IkEKfzXSFqur0cSfnj630EPQfokTYO2Q RCOT/JaNpbUi69MS+d81xFZb5efzzoYE tL3tCE8axm39kzuHKhk2EOSIN8sQPCTC isLppgCbLRPbzKima8Jk5kGs7pV+FK9K vCExdukQ4aB7MYvIZaKzHKP8NAOgKdVk x/BrrGl8IV0T+YvUDo9e8gpdcbhLFXoN w+qZ9xVNIvhSsjzzL1fxrkjJIEdTPzrS HXdUjK8v56KppQJ0pr+XSq2CicRbcn5b ur5HQz4yKfIr2q7aH9CMGuwbMLNDWnjO G+iHdA/ekKLYQ5afWOxaqw==
+SECTION ADDITIONAL
+a.ns.nic.cz. 172800 IN A 194.0.12.1
+a.ns.nic.cz. 172800 IN AAAA 2001:678:f::1
+b.ns.nic.cz. 172800 IN A 194.0.13.1
+b.ns.nic.cz. 172800 IN AAAA 2001:678:10::1
+c.ns.nic.cz. 172800 IN A 194.0.14.1
+c.ns.nic.cz. 172800 IN AAAA 2001:678:11::1
+d.ns.nic.cz. 172800 IN A 193.29.206.1
+d.ns.nic.cz. 172800 IN AAAA 2001:678:1::1
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+a.root-servers.net. IN NS
+SECTION AUTHORITY
+root-servers.net. 3600000 IN SOA a.root-servers.net. nstld.verisign-grs.com. 2019061700 14400 7200 1209600 3600000
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+g.root-servers.net. IN AAAA
+SECTION ANSWER
+g.root-servers.net. 3600000 IN AAAA 2001:500:12::d0d
+SECTION AUTHORITY
+root-servers.net. 3600000 IN NS a.root-servers.net.
+root-servers.net. 3600000 IN NS b.root-servers.net.
+root-servers.net. 3600000 IN NS c.root-servers.net.
+root-servers.net. 3600000 IN NS d.root-servers.net.
+root-servers.net. 3600000 IN NS e.root-servers.net.
+root-servers.net. 3600000 IN NS f.root-servers.net.
+root-servers.net. 3600000 IN NS g.root-servers.net.
+root-servers.net. 3600000 IN NS h.root-servers.net.
+root-servers.net. 3600000 IN NS i.root-servers.net.
+root-servers.net. 3600000 IN NS j.root-servers.net.
+root-servers.net. 3600000 IN NS k.root-servers.net.
+root-servers.net. 3600000 IN NS l.root-servers.net.
+root-servers.net. 3600000 IN NS m.root-servers.net.
+SECTION ADDITIONAL
+a.root-servers.net. 3600000 IN A 198.41.0.4
+a.root-servers.net. 3600000 IN AAAA 2001:503:ba3e::2:30
+b.root-servers.net. 3600000 IN A 199.9.14.201
+b.root-servers.net. 3600000 IN AAAA 2001:500:200::b
+c.root-servers.net. 3600000 IN A 192.33.4.12
+c.root-servers.net. 3600000 IN AAAA 2001:500:2::c
+d.root-servers.net. 3600000 IN A 199.7.91.13
+d.root-servers.net. 3600000 IN AAAA 2001:500:2d::d
+e.root-servers.net. 3600000 IN A 192.203.230.10
+e.root-servers.net. 3600000 IN AAAA 2001:500:a8::e
+f.root-servers.net. 3600000 IN A 192.5.5.241
+f.root-servers.net. 3600000 IN AAAA 2001:500:2f::f
+g.root-servers.net. 3600000 IN A 192.112.36.4
+h.root-servers.net. 3600000 IN A 198.97.190.53
+h.root-servers.net. 3600000 IN AAAA 2001:500:1::53
+i.root-servers.net. 3600000 IN A 192.36.148.17
+i.root-servers.net. 3600000 IN AAAA 2001:7fe::53
+j.root-servers.net. 3600000 IN A 192.58.128.30
+j.root-servers.net. 3600000 IN AAAA 2001:503:c27::2:30
+k.root-servers.net. 3600000 IN A 193.0.14.129
+k.root-servers.net. 3600000 IN AAAA 2001:7fd::1
+l.root-servers.net. 3600000 IN A 199.7.83.42
+l.root-servers.net. 3600000 IN AAAA 2001:500:9f::42
+m.root-servers.net. 3600000 IN A 202.12.27.33
+m.root-servers.net. 3600000 IN AAAA 2001:dc3::35
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+cz. IN DS
+SECTION ANSWER
+cz. 86400 IN DS 20237 13 2 cff0f3ecdbc529c1f0031ba1840bfb835853b9209ed1e508fff48451d7b778e2
+cz. 86400 IN RRSIG DS 8 1 86400 20190708050000 20190625040000 25266 . r7Lxqu4C80oW46tP7BNfJWrXs2K5YEqn IkEKfzXSFqur0cSfnj630EPQfokTYO2Q RCOT/JaNpbUi69MS+d81xFZb5efzzoYE tL3tCE8axm39kzuHKhk2EOSIN8sQPCTC isLppgCbLRPbzKima8Jk5kGs7pV+FK9K vCExdukQ4aB7MYvIZaKzHKP8NAOgKdVk x/BrrGl8IV0T+YvUDo9e8gpdcbhLFXoN w+qZ9xVNIvhSsjzzL1fxrkjJIEdTPzrS HXdUjK8v56KppQJ0pr+XSq2CicRbcn5b ur5HQz4yKfIr2q7aH9CMGuwbMLNDWnjO G+iHdA/ekKLYQ5afWOxaqw==
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+j.root-servers.net. IN AAAA
+SECTION ANSWER
+j.root-servers.net. 3600000 IN AAAA 2001:503:c27::2:30
+SECTION AUTHORITY
+root-servers.net. 3600000 IN NS a.root-servers.net.
+root-servers.net. 3600000 IN NS b.root-servers.net.
+root-servers.net. 3600000 IN NS c.root-servers.net.
+root-servers.net. 3600000 IN NS d.root-servers.net.
+root-servers.net. 3600000 IN NS e.root-servers.net.
+root-servers.net. 3600000 IN NS f.root-servers.net.
+root-servers.net. 3600000 IN NS g.root-servers.net.
+root-servers.net. 3600000 IN NS h.root-servers.net.
+root-servers.net. 3600000 IN NS i.root-servers.net.
+root-servers.net. 3600000 IN NS j.root-servers.net.
+root-servers.net. 3600000 IN NS k.root-servers.net.
+root-servers.net. 3600000 IN NS l.root-servers.net.
+root-servers.net. 3600000 IN NS m.root-servers.net.
+SECTION ADDITIONAL
+a.root-servers.net. 3600000 IN A 198.41.0.4
+a.root-servers.net. 3600000 IN AAAA 2001:503:ba3e::2:30
+b.root-servers.net. 3600000 IN A 199.9.14.201
+b.root-servers.net. 3600000 IN AAAA 2001:500:200::b
+c.root-servers.net. 3600000 IN A 192.33.4.12
+c.root-servers.net. 3600000 IN AAAA 2001:500:2::c
+d.root-servers.net. 3600000 IN A 199.7.91.13
+d.root-servers.net. 3600000 IN AAAA 2001:500:2d::d
+e.root-servers.net. 3600000 IN A 192.203.230.10
+e.root-servers.net. 3600000 IN AAAA 2001:500:a8::e
+f.root-servers.net. 3600000 IN A 192.5.5.241
+f.root-servers.net. 3600000 IN AAAA 2001:500:2f::f
+g.root-servers.net. 3600000 IN A 192.112.36.4
+g.root-servers.net. 3600000 IN AAAA 2001:500:12::d0d
+h.root-servers.net. 3600000 IN A 198.97.190.53
+h.root-servers.net. 3600000 IN AAAA 2001:500:1::53
+i.root-servers.net. 3600000 IN A 192.36.148.17
+i.root-servers.net. 3600000 IN AAAA 2001:7fe::53
+j.root-servers.net. 3600000 IN A 192.58.128.30
+k.root-servers.net. 3600000 IN A 193.0.14.129
+k.root-servers.net. 3600000 IN AAAA 2001:7fd::1
+l.root-servers.net. 3600000 IN A 199.7.83.42
+l.root-servers.net. 3600000 IN AAAA 2001:500:9f::42
+m.root-servers.net. 3600000 IN A 202.12.27.33
+m.root-servers.net. 3600000 IN AAAA 2001:dc3::35
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+d.root-servers.net. IN AAAA
+SECTION ANSWER
+d.root-servers.net. 3600000 IN AAAA 2001:500:2d::d
+SECTION AUTHORITY
+root-servers.net. 3600000 IN NS a.root-servers.net.
+root-servers.net. 3600000 IN NS b.root-servers.net.
+root-servers.net. 3600000 IN NS c.root-servers.net.
+root-servers.net. 3600000 IN NS d.root-servers.net.
+root-servers.net. 3600000 IN NS e.root-servers.net.
+root-servers.net. 3600000 IN NS f.root-servers.net.
+root-servers.net. 3600000 IN NS g.root-servers.net.
+root-servers.net. 3600000 IN NS h.root-servers.net.
+root-servers.net. 3600000 IN NS i.root-servers.net.
+root-servers.net. 3600000 IN NS j.root-servers.net.
+root-servers.net. 3600000 IN NS k.root-servers.net.
+root-servers.net. 3600000 IN NS l.root-servers.net.
+root-servers.net. 3600000 IN NS m.root-servers.net.
+SECTION ADDITIONAL
+a.root-servers.net. 3600000 IN A 198.41.0.4
+a.root-servers.net. 3600000 IN AAAA 2001:503:ba3e::2:30
+b.root-servers.net. 3600000 IN A 199.9.14.201
+b.root-servers.net. 3600000 IN AAAA 2001:500:200::b
+c.root-servers.net. 3600000 IN A 192.33.4.12
+c.root-servers.net. 3600000 IN AAAA 2001:500:2::c
+d.root-servers.net. 3600000 IN A 199.7.91.13
+e.root-servers.net. 3600000 IN A 192.203.230.10
+e.root-servers.net. 3600000 IN AAAA 2001:500:a8::e
+f.root-servers.net. 3600000 IN A 192.5.5.241
+f.root-servers.net. 3600000 IN AAAA 2001:500:2f::f
+g.root-servers.net. 3600000 IN A 192.112.36.4
+g.root-servers.net. 3600000 IN AAAA 2001:500:12::d0d
+h.root-servers.net. 3600000 IN A 198.97.190.53
+h.root-servers.net. 3600000 IN AAAA 2001:500:1::53
+i.root-servers.net. 3600000 IN A 192.36.148.17
+i.root-servers.net. 3600000 IN AAAA 2001:7fe::53
+j.root-servers.net. 3600000 IN A 192.58.128.30
+j.root-servers.net. 3600000 IN AAAA 2001:503:c27::2:30
+k.root-servers.net. 3600000 IN A 193.0.14.129
+k.root-servers.net. 3600000 IN AAAA 2001:7fd::1
+l.root-servers.net. 3600000 IN A 199.7.83.42
+l.root-servers.net. 3600000 IN AAAA 2001:500:9f::42
+m.root-servers.net. 3600000 IN A 202.12.27.33
+m.root-servers.net. 3600000 IN AAAA 2001:dc3::35
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+l.root-servers.net. IN AAAA
+SECTION ANSWER
+l.root-servers.net. 3600000 IN AAAA 2001:500:9f::42
+SECTION AUTHORITY
+root-servers.net. 3600000 IN NS a.root-servers.net.
+root-servers.net. 3600000 IN NS b.root-servers.net.
+root-servers.net. 3600000 IN NS c.root-servers.net.
+root-servers.net. 3600000 IN NS d.root-servers.net.
+root-servers.net. 3600000 IN NS e.root-servers.net.
+root-servers.net. 3600000 IN NS f.root-servers.net.
+root-servers.net. 3600000 IN NS g.root-servers.net.
+root-servers.net. 3600000 IN NS h.root-servers.net.
+root-servers.net. 3600000 IN NS i.root-servers.net.
+root-servers.net. 3600000 IN NS j.root-servers.net.
+root-servers.net. 3600000 IN NS k.root-servers.net.
+root-servers.net. 3600000 IN NS l.root-servers.net.
+root-servers.net. 3600000 IN NS m.root-servers.net.
+SECTION ADDITIONAL
+a.root-servers.net. 3600000 IN A 198.41.0.4
+a.root-servers.net. 3600000 IN AAAA 2001:503:ba3e::2:30
+b.root-servers.net. 3600000 IN A 199.9.14.201
+b.root-servers.net. 3600000 IN AAAA 2001:500:200::b
+c.root-servers.net. 3600000 IN A 192.33.4.12
+c.root-servers.net. 3600000 IN AAAA 2001:500:2::c
+d.root-servers.net. 3600000 IN A 199.7.91.13
+d.root-servers.net. 3600000 IN AAAA 2001:500:2d::d
+e.root-servers.net. 3600000 IN A 192.203.230.10
+e.root-servers.net. 3600000 IN AAAA 2001:500:a8::e
+f.root-servers.net. 3600000 IN A 192.5.5.241
+f.root-servers.net. 3600000 IN AAAA 2001:500:2f::f
+g.root-servers.net. 3600000 IN A 192.112.36.4
+g.root-servers.net. 3600000 IN AAAA 2001:500:12::d0d
+h.root-servers.net. 3600000 IN A 198.97.190.53
+h.root-servers.net. 3600000 IN AAAA 2001:500:1::53
+i.root-servers.net. 3600000 IN A 192.36.148.17
+i.root-servers.net. 3600000 IN AAAA 2001:7fe::53
+j.root-servers.net. 3600000 IN A 192.58.128.30
+j.root-servers.net. 3600000 IN AAAA 2001:503:c27::2:30
+k.root-servers.net. 3600000 IN A 193.0.14.129
+k.root-servers.net. 3600000 IN AAAA 2001:7fd::1
+l.root-servers.net. 3600000 IN A 199.7.83.42
+m.root-servers.net. 3600000 IN A 202.12.27.33
+m.root-servers.net. 3600000 IN AAAA 2001:dc3::35
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+a.root-servers.net. IN AAAA
+SECTION ANSWER
+a.root-servers.net. 3600000 IN AAAA 2001:503:ba3e::2:30
+SECTION AUTHORITY
+root-servers.net. 3600000 IN NS a.root-servers.net.
+root-servers.net. 3600000 IN NS b.root-servers.net.
+root-servers.net. 3600000 IN NS c.root-servers.net.
+root-servers.net. 3600000 IN NS d.root-servers.net.
+root-servers.net. 3600000 IN NS e.root-servers.net.
+root-servers.net. 3600000 IN NS f.root-servers.net.
+root-servers.net. 3600000 IN NS g.root-servers.net.
+root-servers.net. 3600000 IN NS h.root-servers.net.
+root-servers.net. 3600000 IN NS i.root-servers.net.
+root-servers.net. 3600000 IN NS j.root-servers.net.
+root-servers.net. 3600000 IN NS k.root-servers.net.
+root-servers.net. 3600000 IN NS l.root-servers.net.
+root-servers.net. 3600000 IN NS m.root-servers.net.
+SECTION ADDITIONAL
+a.root-servers.net. 3600000 IN A 198.41.0.4
+b.root-servers.net. 3600000 IN A 199.9.14.201
+b.root-servers.net. 3600000 IN AAAA 2001:500:200::b
+c.root-servers.net. 3600000 IN A 192.33.4.12
+c.root-servers.net. 3600000 IN AAAA 2001:500:2::c
+d.root-servers.net. 3600000 IN A 199.7.91.13
+d.root-servers.net. 3600000 IN AAAA 2001:500:2d::d
+e.root-servers.net. 3600000 IN A 192.203.230.10
+e.root-servers.net. 3600000 IN AAAA 2001:500:a8::e
+f.root-servers.net. 3600000 IN A 192.5.5.241
+f.root-servers.net. 3600000 IN AAAA 2001:500:2f::f
+g.root-servers.net. 3600000 IN A 192.112.36.4
+g.root-servers.net. 3600000 IN AAAA 2001:500:12::d0d
+h.root-servers.net. 3600000 IN A 198.97.190.53
+h.root-servers.net. 3600000 IN AAAA 2001:500:1::53
+i.root-servers.net. 3600000 IN A 192.36.148.17
+i.root-servers.net. 3600000 IN AAAA 2001:7fe::53
+j.root-servers.net. 3600000 IN A 192.58.128.30
+j.root-servers.net. 3600000 IN AAAA 2001:503:c27::2:30
+k.root-servers.net. 3600000 IN A 193.0.14.129
+k.root-servers.net. 3600000 IN AAAA 2001:7fd::1
+l.root-servers.net. 3600000 IN A 199.7.83.42
+l.root-servers.net. 3600000 IN AAAA 2001:500:9f::42
+m.root-servers.net. 3600000 IN A 202.12.27.33
+m.root-servers.net. 3600000 IN AAAA 2001:dc3::35
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+e.root-servers.net. IN AAAA
+SECTION ANSWER
+e.root-servers.net. 3600000 IN AAAA 2001:500:a8::e
+SECTION AUTHORITY
+root-servers.net. 3600000 IN NS a.root-servers.net.
+root-servers.net. 3600000 IN NS b.root-servers.net.
+root-servers.net. 3600000 IN NS c.root-servers.net.
+root-servers.net. 3600000 IN NS d.root-servers.net.
+root-servers.net. 3600000 IN NS e.root-servers.net.
+root-servers.net. 3600000 IN NS f.root-servers.net.
+root-servers.net. 3600000 IN NS g.root-servers.net.
+root-servers.net. 3600000 IN NS h.root-servers.net.
+root-servers.net. 3600000 IN NS i.root-servers.net.
+root-servers.net. 3600000 IN NS j.root-servers.net.
+root-servers.net. 3600000 IN NS k.root-servers.net.
+root-servers.net. 3600000 IN NS l.root-servers.net.
+root-servers.net. 3600000 IN NS m.root-servers.net.
+SECTION ADDITIONAL
+a.root-servers.net. 3600000 IN A 198.41.0.4
+a.root-servers.net. 3600000 IN AAAA 2001:503:ba3e::2:30
+b.root-servers.net. 3600000 IN A 199.9.14.201
+b.root-servers.net. 3600000 IN AAAA 2001:500:200::b
+c.root-servers.net. 3600000 IN A 192.33.4.12
+c.root-servers.net. 3600000 IN AAAA 2001:500:2::c
+d.root-servers.net. 3600000 IN A 199.7.91.13
+d.root-servers.net. 3600000 IN AAAA 2001:500:2d::d
+e.root-servers.net. 3600000 IN A 192.203.230.10
+f.root-servers.net. 3600000 IN A 192.5.5.241
+f.root-servers.net. 3600000 IN AAAA 2001:500:2f::f
+g.root-servers.net. 3600000 IN A 192.112.36.4
+g.root-servers.net. 3600000 IN AAAA 2001:500:12::d0d
+h.root-servers.net. 3600000 IN A 198.97.190.53
+h.root-servers.net. 3600000 IN AAAA 2001:500:1::53
+i.root-servers.net. 3600000 IN A 192.36.148.17
+i.root-servers.net. 3600000 IN AAAA 2001:7fe::53
+j.root-servers.net. 3600000 IN A 192.58.128.30
+j.root-servers.net. 3600000 IN AAAA 2001:503:c27::2:30
+k.root-servers.net. 3600000 IN A 193.0.14.129
+k.root-servers.net. 3600000 IN AAAA 2001:7fd::1
+l.root-servers.net. 3600000 IN A 199.7.83.42
+l.root-servers.net. 3600000 IN AAAA 2001:500:9f::42
+m.root-servers.net. 3600000 IN A 202.12.27.33
+m.root-servers.net. 3600000 IN AAAA 2001:dc3::35
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+j.root-servers.net. IN A
+SECTION ANSWER
+j.root-servers.net. 3600000 IN A 192.58.128.30
+SECTION AUTHORITY
+root-servers.net. 3600000 IN NS a.root-servers.net.
+root-servers.net. 3600000 IN NS b.root-servers.net.
+root-servers.net. 3600000 IN NS c.root-servers.net.
+root-servers.net. 3600000 IN NS d.root-servers.net.
+root-servers.net. 3600000 IN NS e.root-servers.net.
+root-servers.net. 3600000 IN NS f.root-servers.net.
+root-servers.net. 3600000 IN NS g.root-servers.net.
+root-servers.net. 3600000 IN NS h.root-servers.net.
+root-servers.net. 3600000 IN NS i.root-servers.net.
+root-servers.net. 3600000 IN NS j.root-servers.net.
+root-servers.net. 3600000 IN NS k.root-servers.net.
+root-servers.net. 3600000 IN NS l.root-servers.net.
+root-servers.net. 3600000 IN NS m.root-servers.net.
+SECTION ADDITIONAL
+a.root-servers.net. 3600000 IN A 198.41.0.4
+a.root-servers.net. 3600000 IN AAAA 2001:503:ba3e::2:30
+b.root-servers.net. 3600000 IN A 199.9.14.201
+b.root-servers.net. 3600000 IN AAAA 2001:500:200::b
+c.root-servers.net. 3600000 IN A 192.33.4.12
+c.root-servers.net. 3600000 IN AAAA 2001:500:2::c
+d.root-servers.net. 3600000 IN A 199.7.91.13
+d.root-servers.net. 3600000 IN AAAA 2001:500:2d::d
+e.root-servers.net. 3600000 IN A 192.203.230.10
+e.root-servers.net. 3600000 IN AAAA 2001:500:a8::e
+f.root-servers.net. 3600000 IN A 192.5.5.241
+f.root-servers.net. 3600000 IN AAAA 2001:500:2f::f
+g.root-servers.net. 3600000 IN A 192.112.36.4
+g.root-servers.net. 3600000 IN AAAA 2001:500:12::d0d
+h.root-servers.net. 3600000 IN A 198.97.190.53
+h.root-servers.net. 3600000 IN AAAA 2001:500:1::53
+i.root-servers.net. 3600000 IN A 192.36.148.17
+i.root-servers.net. 3600000 IN AAAA 2001:7fe::53
+j.root-servers.net. 3600000 IN AAAA 2001:503:c27::2:30
+k.root-servers.net. 3600000 IN A 193.0.14.129
+k.root-servers.net. 3600000 IN AAAA 2001:7fd::1
+l.root-servers.net. 3600000 IN A 199.7.83.42
+l.root-servers.net. 3600000 IN AAAA 2001:500:9f::42
+m.root-servers.net. 3600000 IN A 202.12.27.33
+m.root-servers.net. 3600000 IN AAAA 2001:dc3::35
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+i.root-servers.net. IN NS
+SECTION AUTHORITY
+root-servers.net. 3600000 IN SOA a.root-servers.net. nstld.verisign-grs.com. 2019061700 14400 7200 1209600 3600000
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+k.root-servers.net. IN AAAA
+SECTION ANSWER
+k.root-servers.net. 3600000 IN AAAA 2001:7fd::1
+SECTION AUTHORITY
+root-servers.net. 3600000 IN NS a.root-servers.net.
+root-servers.net. 3600000 IN NS b.root-servers.net.
+root-servers.net. 3600000 IN NS c.root-servers.net.
+root-servers.net. 3600000 IN NS d.root-servers.net.
+root-servers.net. 3600000 IN NS e.root-servers.net.
+root-servers.net. 3600000 IN NS f.root-servers.net.
+root-servers.net. 3600000 IN NS g.root-servers.net.
+root-servers.net. 3600000 IN NS h.root-servers.net.
+root-servers.net. 3600000 IN NS i.root-servers.net.
+root-servers.net. 3600000 IN NS j.root-servers.net.
+root-servers.net. 3600000 IN NS k.root-servers.net.
+root-servers.net. 3600000 IN NS l.root-servers.net.
+root-servers.net. 3600000 IN NS m.root-servers.net.
+SECTION ADDITIONAL
+a.root-servers.net. 3600000 IN A 198.41.0.4
+a.root-servers.net. 3600000 IN AAAA 2001:503:ba3e::2:30
+b.root-servers.net. 3600000 IN A 199.9.14.201
+b.root-servers.net. 3600000 IN AAAA 2001:500:200::b
+c.root-servers.net. 3600000 IN A 192.33.4.12
+c.root-servers.net. 3600000 IN AAAA 2001:500:2::c
+d.root-servers.net. 3600000 IN A 199.7.91.13
+d.root-servers.net. 3600000 IN AAAA 2001:500:2d::d
+e.root-servers.net. 3600000 IN A 192.203.230.10
+e.root-servers.net. 3600000 IN AAAA 2001:500:a8::e
+f.root-servers.net. 3600000 IN A 192.5.5.241
+f.root-servers.net. 3600000 IN AAAA 2001:500:2f::f
+g.root-servers.net. 3600000 IN A 192.112.36.4
+g.root-servers.net. 3600000 IN AAAA 2001:500:12::d0d
+h.root-servers.net. 3600000 IN A 198.97.190.53
+h.root-servers.net. 3600000 IN AAAA 2001:500:1::53
+i.root-servers.net. 3600000 IN A 192.36.148.17
+i.root-servers.net. 3600000 IN AAAA 2001:7fe::53
+j.root-servers.net. 3600000 IN A 192.58.128.30
+j.root-servers.net. 3600000 IN AAAA 2001:503:c27::2:30
+k.root-servers.net. 3600000 IN A 193.0.14.129
+l.root-servers.net. 3600000 IN A 199.7.83.42
+l.root-servers.net. 3600000 IN AAAA 2001:500:9f::42
+m.root-servers.net. 3600000 IN A 202.12.27.33
+m.root-servers.net. 3600000 IN AAAA 2001:dc3::35
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+net. IN DS
+SECTION ANSWER
+net. 86400 IN DS 35886 8 2 7862b27f5f516ebe19680444d4ce5e762981931842c465f00236401d8bd973ee
+net. 86400 IN RRSIG DS 8 1 86400 20190708050000 20190625040000 25266 . EK4wI33V5RQyA5SAxBfX1oTiDeGfOzXr u0OA6KaXALQOMELkugzUD3NipvVpzO7B 0ZYSsnNn+Kk1h0qJBE/ZWpHHZyvZCg1o zo+kq1Z7gGJvlV4Y9XfuwIGPZKL0tlkm LBVSBd36yQy/x4gFyBKvRgIDd1IyKrjT xJYENyNwvtj3MkrT+Njsg1NWXP5ORRx1 r0zVlq2snbJsp8ze+sLYrSqVXbihg4mq JoMe7NB4M9EYEMfBOUcWo8Wrj73jiYRx 0uJ3HfvOHBqBgVFyhMcr4FeCiN9F9V6C xTQBQnL3lQF1TnOhN//Z7h7TvLulxHRu DeKEsZDcoC4el8u1Fx7t/w==
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+f.root-servers.net. IN A
+SECTION ANSWER
+f.root-servers.net. 3600000 IN A 192.5.5.241
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+f.root-servers.net. IN A
+SECTION ANSWER
+f.root-servers.net. 3600000 IN A 192.5.5.241
+SECTION AUTHORITY
+root-servers.net. 3600000 IN NS a.root-servers.net.
+root-servers.net. 3600000 IN NS b.root-servers.net.
+root-servers.net. 3600000 IN NS c.root-servers.net.
+root-servers.net. 3600000 IN NS d.root-servers.net.
+root-servers.net. 3600000 IN NS e.root-servers.net.
+root-servers.net. 3600000 IN NS f.root-servers.net.
+root-servers.net. 3600000 IN NS g.root-servers.net.
+root-servers.net. 3600000 IN NS h.root-servers.net.
+root-servers.net. 3600000 IN NS i.root-servers.net.
+root-servers.net. 3600000 IN NS j.root-servers.net.
+root-servers.net. 3600000 IN NS k.root-servers.net.
+root-servers.net. 3600000 IN NS l.root-servers.net.
+root-servers.net. 3600000 IN NS m.root-servers.net.
+SECTION ADDITIONAL
+a.root-servers.net. 3600000 IN A 198.41.0.4
+a.root-servers.net. 3600000 IN AAAA 2001:503:ba3e::2:30
+b.root-servers.net. 3600000 IN A 199.9.14.201
+b.root-servers.net. 3600000 IN AAAA 2001:500:200::b
+c.root-servers.net. 3600000 IN A 192.33.4.12
+c.root-servers.net. 3600000 IN AAAA 2001:500:2::c
+d.root-servers.net. 3600000 IN A 199.7.91.13
+d.root-servers.net. 3600000 IN AAAA 2001:500:2d::d
+e.root-servers.net. 3600000 IN A 192.203.230.10
+e.root-servers.net. 3600000 IN AAAA 2001:500:a8::e
+f.root-servers.net. 3600000 IN AAAA 2001:500:2f::f
+g.root-servers.net. 3600000 IN A 192.112.36.4
+g.root-servers.net. 3600000 IN AAAA 2001:500:12::d0d
+h.root-servers.net. 3600000 IN A 198.97.190.53
+h.root-servers.net. 3600000 IN AAAA 2001:500:1::53
+i.root-servers.net. 3600000 IN A 192.36.148.17
+i.root-servers.net. 3600000 IN AAAA 2001:7fe::53
+j.root-servers.net. 3600000 IN A 192.58.128.30
+j.root-servers.net. 3600000 IN AAAA 2001:503:c27::2:30
+k.root-servers.net. 3600000 IN A 193.0.14.129
+k.root-servers.net. 3600000 IN AAAA 2001:7fd::1
+l.root-servers.net. 3600000 IN A 199.7.83.42
+l.root-servers.net. 3600000 IN AAAA 2001:500:9f::42
+m.root-servers.net. 3600000 IN A 202.12.27.33
+m.root-servers.net. 3600000 IN AAAA 2001:dc3::35
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+f.root-servers.net. IN AAAA
+SECTION ANSWER
+f.root-servers.net. 3600000 IN AAAA 2001:500:2f::f
+SECTION AUTHORITY
+root-servers.net. 3600000 IN NS a.root-servers.net.
+root-servers.net. 3600000 IN NS b.root-servers.net.
+root-servers.net. 3600000 IN NS c.root-servers.net.
+root-servers.net. 3600000 IN NS d.root-servers.net.
+root-servers.net. 3600000 IN NS e.root-servers.net.
+root-servers.net. 3600000 IN NS f.root-servers.net.
+root-servers.net. 3600000 IN NS g.root-servers.net.
+root-servers.net. 3600000 IN NS h.root-servers.net.
+root-servers.net. 3600000 IN NS i.root-servers.net.
+root-servers.net. 3600000 IN NS j.root-servers.net.
+root-servers.net. 3600000 IN NS k.root-servers.net.
+root-servers.net. 3600000 IN NS l.root-servers.net.
+root-servers.net. 3600000 IN NS m.root-servers.net.
+SECTION ADDITIONAL
+a.root-servers.net. 3600000 IN A 198.41.0.4
+a.root-servers.net. 3600000 IN AAAA 2001:503:ba3e::2:30
+b.root-servers.net. 3600000 IN A 199.9.14.201
+b.root-servers.net. 3600000 IN AAAA 2001:500:200::b
+c.root-servers.net. 3600000 IN A 192.33.4.12
+c.root-servers.net. 3600000 IN AAAA 2001:500:2::c
+d.root-servers.net. 3600000 IN A 199.7.91.13
+d.root-servers.net. 3600000 IN AAAA 2001:500:2d::d
+e.root-servers.net. 3600000 IN A 192.203.230.10
+e.root-servers.net. 3600000 IN AAAA 2001:500:a8::e
+f.root-servers.net. 3600000 IN A 192.5.5.241
+g.root-servers.net. 3600000 IN A 192.112.36.4
+g.root-servers.net. 3600000 IN AAAA 2001:500:12::d0d
+h.root-servers.net. 3600000 IN A 198.97.190.53
+h.root-servers.net. 3600000 IN AAAA 2001:500:1::53
+i.root-servers.net. 3600000 IN A 192.36.148.17
+i.root-servers.net. 3600000 IN AAAA 2001:7fe::53
+j.root-servers.net. 3600000 IN A 192.58.128.30
+j.root-servers.net. 3600000 IN AAAA 2001:503:c27::2:30
+k.root-servers.net. 3600000 IN A 193.0.14.129
+k.root-servers.net. 3600000 IN AAAA 2001:7fd::1
+l.root-servers.net. 3600000 IN A 199.7.83.42
+l.root-servers.net. 3600000 IN AAAA 2001:500:9f::42
+m.root-servers.net. 3600000 IN A 202.12.27.33
+m.root-servers.net. 3600000 IN AAAA 2001:dc3::35
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+h.root-servers.net. IN AAAA
+SECTION ANSWER
+h.root-servers.net. 3600000 IN AAAA 2001:500:1::53
+SECTION AUTHORITY
+root-servers.net. 3600000 IN NS a.root-servers.net.
+root-servers.net. 3600000 IN NS b.root-servers.net.
+root-servers.net. 3600000 IN NS c.root-servers.net.
+root-servers.net. 3600000 IN NS d.root-servers.net.
+root-servers.net. 3600000 IN NS e.root-servers.net.
+root-servers.net. 3600000 IN NS f.root-servers.net.
+root-servers.net. 3600000 IN NS g.root-servers.net.
+root-servers.net. 3600000 IN NS h.root-servers.net.
+root-servers.net. 3600000 IN NS i.root-servers.net.
+root-servers.net. 3600000 IN NS j.root-servers.net.
+root-servers.net. 3600000 IN NS k.root-servers.net.
+root-servers.net. 3600000 IN NS l.root-servers.net.
+root-servers.net. 3600000 IN NS m.root-servers.net.
+SECTION ADDITIONAL
+a.root-servers.net. 3600000 IN A 198.41.0.4
+a.root-servers.net. 3600000 IN AAAA 2001:503:ba3e::2:30
+b.root-servers.net. 3600000 IN A 199.9.14.201
+b.root-servers.net. 3600000 IN AAAA 2001:500:200::b
+c.root-servers.net. 3600000 IN A 192.33.4.12
+c.root-servers.net. 3600000 IN AAAA 2001:500:2::c
+d.root-servers.net. 3600000 IN A 199.7.91.13
+d.root-servers.net. 3600000 IN AAAA 2001:500:2d::d
+e.root-servers.net. 3600000 IN A 192.203.230.10
+e.root-servers.net. 3600000 IN AAAA 2001:500:a8::e
+f.root-servers.net. 3600000 IN A 192.5.5.241
+f.root-servers.net. 3600000 IN AAAA 2001:500:2f::f
+g.root-servers.net. 3600000 IN A 192.112.36.4
+g.root-servers.net. 3600000 IN AAAA 2001:500:12::d0d
+h.root-servers.net. 3600000 IN A 198.97.190.53
+i.root-servers.net. 3600000 IN A 192.36.148.17
+i.root-servers.net. 3600000 IN AAAA 2001:7fe::53
+j.root-servers.net. 3600000 IN A 192.58.128.30
+j.root-servers.net. 3600000 IN AAAA 2001:503:c27::2:30
+k.root-servers.net. 3600000 IN A 193.0.14.129
+k.root-servers.net. 3600000 IN AAAA 2001:7fd::1
+l.root-servers.net. 3600000 IN A 199.7.83.42
+l.root-servers.net. 3600000 IN AAAA 2001:500:9f::42
+m.root-servers.net. 3600000 IN A 202.12.27.33
+m.root-servers.net. 3600000 IN AAAA 2001:dc3::35
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+e.root-servers.net. IN NS
+SECTION AUTHORITY
+root-servers.net. 3600000 IN SOA a.root-servers.net. nstld.verisign-grs.com. 2019061700 14400 7200 1209600 3600000
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+b.root-servers.net. IN AAAA
+SECTION ANSWER
+b.root-servers.net. 3600000 IN AAAA 2001:500:200::b
+SECTION AUTHORITY
+root-servers.net. 3600000 IN NS a.root-servers.net.
+root-servers.net. 3600000 IN NS b.root-servers.net.
+root-servers.net. 3600000 IN NS c.root-servers.net.
+root-servers.net. 3600000 IN NS d.root-servers.net.
+root-servers.net. 3600000 IN NS e.root-servers.net.
+root-servers.net. 3600000 IN NS f.root-servers.net.
+root-servers.net. 3600000 IN NS g.root-servers.net.
+root-servers.net. 3600000 IN NS h.root-servers.net.
+root-servers.net. 3600000 IN NS i.root-servers.net.
+root-servers.net. 3600000 IN NS j.root-servers.net.
+root-servers.net. 3600000 IN NS k.root-servers.net.
+root-servers.net. 3600000 IN NS l.root-servers.net.
+root-servers.net. 3600000 IN NS m.root-servers.net.
+SECTION ADDITIONAL
+a.root-servers.net. 3600000 IN A 198.41.0.4
+a.root-servers.net. 3600000 IN AAAA 2001:503:ba3e::2:30
+b.root-servers.net. 3600000 IN A 199.9.14.201
+c.root-servers.net. 3600000 IN A 192.33.4.12
+c.root-servers.net. 3600000 IN AAAA 2001:500:2::c
+d.root-servers.net. 3600000 IN A 199.7.91.13
+d.root-servers.net. 3600000 IN AAAA 2001:500:2d::d
+e.root-servers.net. 3600000 IN A 192.203.230.10
+e.root-servers.net. 3600000 IN AAAA 2001:500:a8::e
+f.root-servers.net. 3600000 IN A 192.5.5.241
+f.root-servers.net. 3600000 IN AAAA 2001:500:2f::f
+g.root-servers.net. 3600000 IN A 192.112.36.4
+g.root-servers.net. 3600000 IN AAAA 2001:500:12::d0d
+h.root-servers.net. 3600000 IN A 198.97.190.53
+h.root-servers.net. 3600000 IN AAAA 2001:500:1::53
+i.root-servers.net. 3600000 IN A 192.36.148.17
+i.root-servers.net. 3600000 IN AAAA 2001:7fe::53
+j.root-servers.net. 3600000 IN A 192.58.128.30
+j.root-servers.net. 3600000 IN AAAA 2001:503:c27::2:30
+k.root-servers.net. 3600000 IN A 193.0.14.129
+k.root-servers.net. 3600000 IN AAAA 2001:7fd::1
+l.root-servers.net. 3600000 IN A 199.7.83.42
+l.root-servers.net. 3600000 IN AAAA 2001:500:9f::42
+m.root-servers.net. 3600000 IN A 202.12.27.33
+m.root-servers.net. 3600000 IN AAAA 2001:dc3::35
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR RD NOERROR
+SECTION QUESTION
+gtld-servers.net. IN DS
+SECTION AUTHORITY
+net. 172800 IN NS a.gtld-servers.net.
+net. 172800 IN NS b.gtld-servers.net.
+net. 172800 IN NS c.gtld-servers.net.
+net. 172800 IN NS d.gtld-servers.net.
+net. 172800 IN NS e.gtld-servers.net.
+net. 172800 IN NS f.gtld-servers.net.
+net. 172800 IN NS g.gtld-servers.net.
+net. 172800 IN NS h.gtld-servers.net.
+net. 172800 IN NS i.gtld-servers.net.
+net. 172800 IN NS j.gtld-servers.net.
+net. 172800 IN NS k.gtld-servers.net.
+net. 172800 IN NS l.gtld-servers.net.
+net. 172800 IN NS m.gtld-servers.net.
+net. 86400 IN DS 35886 8 2 7862b27f5f516ebe19680444d4ce5e762981931842c465f00236401d8bd973ee
+net. 86400 IN RRSIG DS 8 1 86400 20190708050000 20190625040000 25266 . EK4wI33V5RQyA5SAxBfX1oTiDeGfOzXr u0OA6KaXALQOMELkugzUD3NipvVpzO7B 0ZYSsnNn+Kk1h0qJBE/ZWpHHZyvZCg1o zo+kq1Z7gGJvlV4Y9XfuwIGPZKL0tlkm LBVSBd36yQy/x4gFyBKvRgIDd1IyKrjT xJYENyNwvtj3MkrT+Njsg1NWXP5ORRx1 r0zVlq2snbJsp8ze+sLYrSqVXbihg4mq JoMe7NB4M9EYEMfBOUcWo8Wrj73jiYRx 0uJ3HfvOHBqBgVFyhMcr4FeCiN9F9V6C xTQBQnL3lQF1TnOhN//Z7h7TvLulxHRu DeKEsZDcoC4el8u1Fx7t/w==
+SECTION ADDITIONAL
+a.gtld-servers.net. 172800 IN A 192.5.6.30
+a.gtld-servers.net. 172800 IN AAAA 2001:503:a83e::2:30
+b.gtld-servers.net. 172800 IN A 192.33.14.30
+b.gtld-servers.net. 172800 IN AAAA 2001:503:231d::2:30
+c.gtld-servers.net. 172800 IN A 192.26.92.30
+c.gtld-servers.net. 172800 IN AAAA 2001:503:83eb::30
+d.gtld-servers.net. 172800 IN A 192.31.80.30
+d.gtld-servers.net. 172800 IN AAAA 2001:500:856e::30
+e.gtld-servers.net. 172800 IN A 192.12.94.30
+e.gtld-servers.net. 172800 IN AAAA 2001:502:1ca1::30
+f.gtld-servers.net. 172800 IN A 192.35.51.30
+f.gtld-servers.net. 172800 IN AAAA 2001:503:d414::30
+g.gtld-servers.net. 172800 IN A 192.42.93.30
+g.gtld-servers.net. 172800 IN AAAA 2001:503:eea3::30
+h.gtld-servers.net. 172800 IN A 192.54.112.30
+h.gtld-servers.net. 172800 IN AAAA 2001:502:8cc::30
+i.gtld-servers.net. 172800 IN A 192.43.172.30
+i.gtld-servers.net. 172800 IN AAAA 2001:503:39c1::30
+j.gtld-servers.net. 172800 IN A 192.48.79.30
+j.gtld-servers.net. 172800 IN AAAA 2001:502:7094::30
+k.gtld-servers.net. 172800 IN A 192.52.178.30
+k.gtld-servers.net. 172800 IN AAAA 2001:503:d2d::30
+l.gtld-servers.net. 172800 IN A 192.41.162.30
+l.gtld-servers.net. 172800 IN AAAA 2001:500:d937::30
+m.gtld-servers.net. 172800 IN A 192.55.83.30
+m.gtld-servers.net. 172800 IN AAAA 2001:501:b1f9::30
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR RD NOERROR
+SECTION QUESTION
+nstld.com. IN DS
+SECTION AUTHORITY
+com. 172800 IN NS a.gtld-servers.net.
+com. 172800 IN NS b.gtld-servers.net.
+com. 172800 IN NS c.gtld-servers.net.
+com. 172800 IN NS d.gtld-servers.net.
+com. 172800 IN NS e.gtld-servers.net.
+com. 172800 IN NS f.gtld-servers.net.
+com. 172800 IN NS g.gtld-servers.net.
+com. 172800 IN NS h.gtld-servers.net.
+com. 172800 IN NS i.gtld-servers.net.
+com. 172800 IN NS j.gtld-servers.net.
+com. 172800 IN NS k.gtld-servers.net.
+com. 172800 IN NS l.gtld-servers.net.
+com. 172800 IN NS m.gtld-servers.net.
+com. 86400 IN DS 30909 8 2 e2d3c916f6deeac73294e8268fb5885044a833fc5459588f4a9184cfc41a5766
+com. 86400 IN RRSIG DS 8 1 86400 20190708050000 20190625040000 25266 . h8CYVMqouUO2IAPlG4Iqf06ykpl07wny KuM2dRGhrfx5hQbF0CpzGRwT2B6i2drI td9i7BSA4GVKLlTYr9n3Xd+BcAHKwywv 44A2WmTAo3xWMv4THwowwu29B4bAKe0V WQKDfmZ92m1yn8T3MCNZWtuGGaLcY6+g fKgyuHu5fEakVn2GFMdAMayBBFTF0bp4 hVFuNSJBe/1EnFZMcxU9aNuCyC8xup25 7K3x1rcM0hthHr8o0Vevpima1YXsWDGb RDIkDyStPDIQ1c0C9LHMaaGR+MA+fxoL 2x4w2lwOptCK//zpfyPvj11oIyouwgdh Fe3PCf9hS03Y1FsiY+mtWw==
+SECTION ADDITIONAL
+a.gtld-servers.net. 172800 IN A 192.5.6.30
+a.gtld-servers.net. 172800 IN AAAA 2001:503:a83e::2:30
+b.gtld-servers.net. 172800 IN A 192.33.14.30
+b.gtld-servers.net. 172800 IN AAAA 2001:503:231d::2:30
+c.gtld-servers.net. 172800 IN A 192.26.92.30
+c.gtld-servers.net. 172800 IN AAAA 2001:503:83eb::30
+d.gtld-servers.net. 172800 IN A 192.31.80.30
+d.gtld-servers.net. 172800 IN AAAA 2001:500:856e::30
+e.gtld-servers.net. 172800 IN A 192.12.94.30
+e.gtld-servers.net. 172800 IN AAAA 2001:502:1ca1::30
+f.gtld-servers.net. 172800 IN A 192.35.51.30
+f.gtld-servers.net. 172800 IN AAAA 2001:503:d414::30
+g.gtld-servers.net. 172800 IN A 192.42.93.30
+g.gtld-servers.net. 172800 IN AAAA 2001:503:eea3::30
+h.gtld-servers.net. 172800 IN A 192.54.112.30
+h.gtld-servers.net. 172800 IN AAAA 2001:502:8cc::30
+i.gtld-servers.net. 172800 IN A 192.43.172.30
+i.gtld-servers.net. 172800 IN AAAA 2001:503:39c1::30
+j.gtld-servers.net. 172800 IN A 192.48.79.30
+j.gtld-servers.net. 172800 IN AAAA 2001:502:7094::30
+k.gtld-servers.net. 172800 IN A 192.52.178.30
+k.gtld-servers.net. 172800 IN AAAA 2001:503:d2d::30
+l.gtld-servers.net. 172800 IN A 192.41.162.30
+l.gtld-servers.net. 172800 IN AAAA 2001:500:d937::30
+m.gtld-servers.net. 172800 IN A 192.55.83.30
+m.gtld-servers.net. 172800 IN AAAA 2001:501:b1f9::30
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+m.root-servers.net. IN A
+SECTION ANSWER
+m.root-servers.net. 3600000 IN A 202.12.27.33
+SECTION AUTHORITY
+root-servers.net. 3600000 IN NS a.root-servers.net.
+root-servers.net. 3600000 IN NS b.root-servers.net.
+root-servers.net. 3600000 IN NS c.root-servers.net.
+root-servers.net. 3600000 IN NS d.root-servers.net.
+root-servers.net. 3600000 IN NS e.root-servers.net.
+root-servers.net. 3600000 IN NS f.root-servers.net.
+root-servers.net. 3600000 IN NS g.root-servers.net.
+root-servers.net. 3600000 IN NS h.root-servers.net.
+root-servers.net. 3600000 IN NS i.root-servers.net.
+root-servers.net. 3600000 IN NS j.root-servers.net.
+root-servers.net. 3600000 IN NS k.root-servers.net.
+root-servers.net. 3600000 IN NS l.root-servers.net.
+root-servers.net. 3600000 IN NS m.root-servers.net.
+SECTION ADDITIONAL
+a.root-servers.net. 3600000 IN A 198.41.0.4
+a.root-servers.net. 3600000 IN AAAA 2001:503:ba3e::2:30
+b.root-servers.net. 3600000 IN A 199.9.14.201
+b.root-servers.net. 3600000 IN AAAA 2001:500:200::b
+c.root-servers.net. 3600000 IN A 192.33.4.12
+c.root-servers.net. 3600000 IN AAAA 2001:500:2::c
+d.root-servers.net. 3600000 IN A 199.7.91.13
+d.root-servers.net. 3600000 IN AAAA 2001:500:2d::d
+e.root-servers.net. 3600000 IN A 192.203.230.10
+e.root-servers.net. 3600000 IN AAAA 2001:500:a8::e
+f.root-servers.net. 3600000 IN A 192.5.5.241
+f.root-servers.net. 3600000 IN AAAA 2001:500:2f::f
+g.root-servers.net. 3600000 IN A 192.112.36.4
+g.root-servers.net. 3600000 IN AAAA 2001:500:12::d0d
+h.root-servers.net. 3600000 IN A 198.97.190.53
+h.root-servers.net. 3600000 IN AAAA 2001:500:1::53
+i.root-servers.net. 3600000 IN A 192.36.148.17
+i.root-servers.net. 3600000 IN AAAA 2001:7fe::53
+j.root-servers.net. 3600000 IN A 192.58.128.30
+j.root-servers.net. 3600000 IN AAAA 2001:503:c27::2:30
+k.root-servers.net. 3600000 IN A 193.0.14.129
+k.root-servers.net. 3600000 IN AAAA 2001:7fd::1
+l.root-servers.net. 3600000 IN A 199.7.83.42
+l.root-servers.net. 3600000 IN AAAA 2001:500:9f::42
+m.root-servers.net. 3600000 IN AAAA 2001:dc3::35
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+h.root-servers.net. IN A
+SECTION ANSWER
+h.root-servers.net. 3600000 IN A 198.97.190.53
+SECTION AUTHORITY
+root-servers.net. 3600000 IN NS a.root-servers.net.
+root-servers.net. 3600000 IN NS b.root-servers.net.
+root-servers.net. 3600000 IN NS c.root-servers.net.
+root-servers.net. 3600000 IN NS d.root-servers.net.
+root-servers.net. 3600000 IN NS e.root-servers.net.
+root-servers.net. 3600000 IN NS f.root-servers.net.
+root-servers.net. 3600000 IN NS g.root-servers.net.
+root-servers.net. 3600000 IN NS h.root-servers.net.
+root-servers.net. 3600000 IN NS i.root-servers.net.
+root-servers.net. 3600000 IN NS j.root-servers.net.
+root-servers.net. 3600000 IN NS k.root-servers.net.
+root-servers.net. 3600000 IN NS l.root-servers.net.
+root-servers.net. 3600000 IN NS m.root-servers.net.
+SECTION ADDITIONAL
+a.root-servers.net. 3600000 IN A 198.41.0.4
+a.root-servers.net. 3600000 IN AAAA 2001:503:ba3e::2:30
+b.root-servers.net. 3600000 IN A 199.9.14.201
+b.root-servers.net. 3600000 IN AAAA 2001:500:200::b
+c.root-servers.net. 3600000 IN A 192.33.4.12
+c.root-servers.net. 3600000 IN AAAA 2001:500:2::c
+d.root-servers.net. 3600000 IN A 199.7.91.13
+d.root-servers.net. 3600000 IN AAAA 2001:500:2d::d
+e.root-servers.net. 3600000 IN A 192.203.230.10
+e.root-servers.net. 3600000 IN AAAA 2001:500:a8::e
+f.root-servers.net. 3600000 IN A 192.5.5.241
+f.root-servers.net. 3600000 IN AAAA 2001:500:2f::f
+g.root-servers.net. 3600000 IN A 192.112.36.4
+g.root-servers.net. 3600000 IN AAAA 2001:500:12::d0d
+h.root-servers.net. 3600000 IN AAAA 2001:500:1::53
+i.root-servers.net. 3600000 IN A 192.36.148.17
+i.root-servers.net. 3600000 IN AAAA 2001:7fe::53
+j.root-servers.net. 3600000 IN A 192.58.128.30
+j.root-servers.net. 3600000 IN AAAA 2001:503:c27::2:30
+k.root-servers.net. 3600000 IN A 193.0.14.129
+k.root-servers.net. 3600000 IN AAAA 2001:7fd::1
+l.root-servers.net. 3600000 IN A 199.7.83.42
+l.root-servers.net. 3600000 IN AAAA 2001:500:9f::42
+m.root-servers.net. 3600000 IN A 202.12.27.33
+m.root-servers.net. 3600000 IN AAAA 2001:dc3::35
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+com. IN DS
+SECTION ANSWER
+com. 86400 IN DS 30909 8 2 e2d3c916f6deeac73294e8268fb5885044a833fc5459588f4a9184cfc41a5766
+com. 86400 IN RRSIG DS 8 1 86400 20190708050000 20190625040000 25266 . h8CYVMqouUO2IAPlG4Iqf06ykpl07wny KuM2dRGhrfx5hQbF0CpzGRwT2B6i2drI td9i7BSA4GVKLlTYr9n3Xd+BcAHKwywv 44A2WmTAo3xWMv4THwowwu29B4bAKe0V WQKDfmZ92m1yn8T3MCNZWtuGGaLcY6+g fKgyuHu5fEakVn2GFMdAMayBBFTF0bp4 hVFuNSJBe/1EnFZMcxU9aNuCyC8xup25 7K3x1rcM0hthHr8o0Vevpima1YXsWDGb RDIkDyStPDIQ1c0C9LHMaaGR+MA+fxoL 2x4w2lwOptCK//zpfyPvj11oIyouwgdh Fe3PCf9hS03Y1FsiY+mtWw==
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR RD NOERROR
+SECTION QUESTION
+nic.cz. IN DS
+SECTION AUTHORITY
+cz. 172800 IN NS a.ns.nic.cz.
+cz. 172800 IN NS b.ns.nic.cz.
+cz. 172800 IN NS c.ns.nic.cz.
+cz. 172800 IN NS d.ns.nic.cz.
+cz. 86400 IN DS 20237 13 2 cff0f3ecdbc529c1f0031ba1840bfb835853b9209ed1e508fff48451d7b778e2
+cz. 86400 IN RRSIG DS 8 1 86400 20190708050000 20190625040000 25266 . r7Lxqu4C80oW46tP7BNfJWrXs2K5YEqn IkEKfzXSFqur0cSfnj630EPQfokTYO2Q RCOT/JaNpbUi69MS+d81xFZb5efzzoYE tL3tCE8axm39kzuHKhk2EOSIN8sQPCTC isLppgCbLRPbzKima8Jk5kGs7pV+FK9K vCExdukQ4aB7MYvIZaKzHKP8NAOgKdVk x/BrrGl8IV0T+YvUDo9e8gpdcbhLFXoN w+qZ9xVNIvhSsjzzL1fxrkjJIEdTPzrS HXdUjK8v56KppQJ0pr+XSq2CicRbcn5b ur5HQz4yKfIr2q7aH9CMGuwbMLNDWnjO G+iHdA/ekKLYQ5afWOxaqw==
+SECTION ADDITIONAL
+a.ns.nic.cz. 172800 IN A 194.0.12.1
+a.ns.nic.cz. 172800 IN AAAA 2001:678:f::1
+b.ns.nic.cz. 172800 IN A 194.0.13.1
+b.ns.nic.cz. 172800 IN AAAA 2001:678:10::1
+c.ns.nic.cz. 172800 IN A 194.0.14.1
+c.ns.nic.cz. 172800 IN AAAA 2001:678:11::1
+d.ns.nic.cz. 172800 IN A 193.29.206.1
+d.ns.nic.cz. 172800 IN AAAA 2001:678:1::1
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+l.root-servers.net. IN A
+SECTION ANSWER
+l.root-servers.net. 3600000 IN A 199.7.83.42
+SECTION AUTHORITY
+root-servers.net. 3600000 IN NS a.root-servers.net.
+root-servers.net. 3600000 IN NS b.root-servers.net.
+root-servers.net. 3600000 IN NS c.root-servers.net.
+root-servers.net. 3600000 IN NS d.root-servers.net.
+root-servers.net. 3600000 IN NS e.root-servers.net.
+root-servers.net. 3600000 IN NS f.root-servers.net.
+root-servers.net. 3600000 IN NS g.root-servers.net.
+root-servers.net. 3600000 IN NS h.root-servers.net.
+root-servers.net. 3600000 IN NS i.root-servers.net.
+root-servers.net. 3600000 IN NS j.root-servers.net.
+root-servers.net. 3600000 IN NS k.root-servers.net.
+root-servers.net. 3600000 IN NS l.root-servers.net.
+root-servers.net. 3600000 IN NS m.root-servers.net.
+SECTION ADDITIONAL
+a.root-servers.net. 3600000 IN A 198.41.0.4
+a.root-servers.net. 3600000 IN AAAA 2001:503:ba3e::2:30
+b.root-servers.net. 3600000 IN A 199.9.14.201
+b.root-servers.net. 3600000 IN AAAA 2001:500:200::b
+c.root-servers.net. 3600000 IN A 192.33.4.12
+c.root-servers.net. 3600000 IN AAAA 2001:500:2::c
+d.root-servers.net. 3600000 IN A 199.7.91.13
+d.root-servers.net. 3600000 IN AAAA 2001:500:2d::d
+e.root-servers.net. 3600000 IN A 192.203.230.10
+e.root-servers.net. 3600000 IN AAAA 2001:500:a8::e
+f.root-servers.net. 3600000 IN A 192.5.5.241
+f.root-servers.net. 3600000 IN AAAA 2001:500:2f::f
+g.root-servers.net. 3600000 IN A 192.112.36.4
+g.root-servers.net. 3600000 IN AAAA 2001:500:12::d0d
+h.root-servers.net. 3600000 IN A 198.97.190.53
+h.root-servers.net. 3600000 IN AAAA 2001:500:1::53
+i.root-servers.net. 3600000 IN A 192.36.148.17
+i.root-servers.net. 3600000 IN AAAA 2001:7fe::53
+j.root-servers.net. 3600000 IN A 192.58.128.30
+j.root-servers.net. 3600000 IN AAAA 2001:503:c27::2:30
+k.root-servers.net. 3600000 IN A 193.0.14.129
+k.root-servers.net. 3600000 IN AAAA 2001:7fd::1
+l.root-servers.net. 3600000 IN AAAA 2001:500:9f::42
+m.root-servers.net. 3600000 IN A 202.12.27.33
+m.root-servers.net. 3600000 IN AAAA 2001:dc3::35
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+d.root-servers.net. IN NS
+SECTION AUTHORITY
+root-servers.net. 3600000 IN SOA a.root-servers.net. nstld.verisign-grs.com. 2019061700 14400 7200 1209600 3600000
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH subdomain
+ADJUST copy_id copy_query
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+root-servers.net. IN NS
+SECTION ANSWER
+root-servers.net. 3600000 IN NS a.root-servers.net.
+root-servers.net. 3600000 IN NS b.root-servers.net.
+root-servers.net. 3600000 IN NS c.root-servers.net.
+root-servers.net. 3600000 IN NS d.root-servers.net.
+root-servers.net. 3600000 IN NS e.root-servers.net.
+root-servers.net. 3600000 IN NS f.root-servers.net.
+root-servers.net. 3600000 IN NS g.root-servers.net.
+root-servers.net. 3600000 IN NS h.root-servers.net.
+root-servers.net. 3600000 IN NS i.root-servers.net.
+root-servers.net. 3600000 IN NS j.root-servers.net.
+root-servers.net. 3600000 IN NS k.root-servers.net.
+root-servers.net. 3600000 IN NS l.root-servers.net.
+root-servers.net. 3600000 IN NS m.root-servers.net.
+SECTION ADDITIONAL
+a.root-servers.net. 3600000 IN A 198.41.0.4
+a.root-servers.net. 3600000 IN AAAA 2001:503:ba3e::2:30
+b.root-servers.net. 3600000 IN A 199.9.14.201
+b.root-servers.net. 3600000 IN AAAA 2001:500:200::b
+c.root-servers.net. 3600000 IN A 192.33.4.12
+c.root-servers.net. 3600000 IN AAAA 2001:500:2::c
+d.root-servers.net. 3600000 IN A 199.7.91.13
+d.root-servers.net. 3600000 IN AAAA 2001:500:2d::d
+e.root-servers.net. 3600000 IN A 192.203.230.10
+e.root-servers.net. 3600000 IN AAAA 2001:500:a8::e
+f.root-servers.net. 3600000 IN A 192.5.5.241
+f.root-servers.net. 3600000 IN AAAA 2001:500:2f::f
+g.root-servers.net. 3600000 IN A 192.112.36.4
+g.root-servers.net. 3600000 IN AAAA 2001:500:12::d0d
+h.root-servers.net. 3600000 IN A 198.97.190.53
+h.root-servers.net. 3600000 IN AAAA 2001:500:1::53
+i.root-servers.net. 3600000 IN A 192.36.148.17
+i.root-servers.net. 3600000 IN AAAA 2001:7fe::53
+j.root-servers.net. 3600000 IN A 192.58.128.30
+j.root-servers.net. 3600000 IN AAAA 2001:503:c27::2:30
+k.root-servers.net. 3600000 IN A 193.0.14.129
+k.root-servers.net. 3600000 IN AAAA 2001:7fd::1
+l.root-servers.net. 3600000 IN A 199.7.83.42
+l.root-servers.net. 3600000 IN AAAA 2001:500:9f::42
+m.root-servers.net. 3600000 IN A 202.12.27.33
+m.root-servers.net. 3600000 IN AAAA 2001:dc3::35
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH subdomain
+ADJUST copy_id copy_query
+REPLY QR RD NOERROR
+SECTION QUESTION
+cz. IN NS
+SECTION AUTHORITY
+cz. 172800 IN NS a.ns.nic.cz.
+cz. 172800 IN NS b.ns.nic.cz.
+cz. 172800 IN NS c.ns.nic.cz.
+cz. 172800 IN NS d.ns.nic.cz.
+cz. 86400 IN DS 20237 13 2 cff0f3ecdbc529c1f0031ba1840bfb835853b9209ed1e508fff48451d7b778e2
+cz. 86400 IN RRSIG DS 8 1 86400 20190708050000 20190625040000 25266 . r7Lxqu4C80oW46tP7BNfJWrXs2K5YEqn IkEKfzXSFqur0cSfnj630EPQfokTYO2Q RCOT/JaNpbUi69MS+d81xFZb5efzzoYE tL3tCE8axm39kzuHKhk2EOSIN8sQPCTC isLppgCbLRPbzKima8Jk5kGs7pV+FK9K vCExdukQ4aB7MYvIZaKzHKP8NAOgKdVk x/BrrGl8IV0T+YvUDo9e8gpdcbhLFXoN w+qZ9xVNIvhSsjzzL1fxrkjJIEdTPzrS HXdUjK8v56KppQJ0pr+XSq2CicRbcn5b ur5HQz4yKfIr2q7aH9CMGuwbMLNDWnjO G+iHdA/ekKLYQ5afWOxaqw==
+SECTION ADDITIONAL
+a.ns.nic.cz. 172800 IN A 194.0.12.1
+a.ns.nic.cz. 172800 IN AAAA 2001:678:f::1
+b.ns.nic.cz. 172800 IN A 194.0.13.1
+b.ns.nic.cz. 172800 IN AAAA 2001:678:10::1
+c.ns.nic.cz. 172800 IN A 194.0.14.1
+c.ns.nic.cz. 172800 IN AAAA 2001:678:11::1
+d.ns.nic.cz. 172800 IN A 193.29.206.1
+d.ns.nic.cz. 172800 IN AAAA 2001:678:1::1
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH subdomain
+ADJUST copy_id copy_query
+REPLY QR RD NOERROR
+SECTION QUESTION
+net. IN NS
+SECTION AUTHORITY
+net. 172800 IN NS a.gtld-servers.net.
+net. 172800 IN NS b.gtld-servers.net.
+net. 172800 IN NS c.gtld-servers.net.
+net. 172800 IN NS d.gtld-servers.net.
+net. 172800 IN NS e.gtld-servers.net.
+net. 172800 IN NS f.gtld-servers.net.
+net. 172800 IN NS g.gtld-servers.net.
+net. 172800 IN NS h.gtld-servers.net.
+net. 172800 IN NS i.gtld-servers.net.
+net. 172800 IN NS j.gtld-servers.net.
+net. 172800 IN NS k.gtld-servers.net.
+net. 172800 IN NS l.gtld-servers.net.
+net. 172800 IN NS m.gtld-servers.net.
+net. 86400 IN DS 35886 8 2 7862b27f5f516ebe19680444d4ce5e762981931842c465f00236401d8bd973ee
+net. 86400 IN RRSIG DS 8 1 86400 20190708050000 20190625040000 25266 . EK4wI33V5RQyA5SAxBfX1oTiDeGfOzXr u0OA6KaXALQOMELkugzUD3NipvVpzO7B 0ZYSsnNn+Kk1h0qJBE/ZWpHHZyvZCg1o zo+kq1Z7gGJvlV4Y9XfuwIGPZKL0tlkm LBVSBd36yQy/x4gFyBKvRgIDd1IyKrjT xJYENyNwvtj3MkrT+Njsg1NWXP5ORRx1 r0zVlq2snbJsp8ze+sLYrSqVXbihg4mq JoMe7NB4M9EYEMfBOUcWo8Wrj73jiYRx 0uJ3HfvOHBqBgVFyhMcr4FeCiN9F9V6C xTQBQnL3lQF1TnOhN//Z7h7TvLulxHRu DeKEsZDcoC4el8u1Fx7t/w==
+SECTION ADDITIONAL
+a.gtld-servers.net. 172800 IN A 192.5.6.30
+a.gtld-servers.net. 172800 IN AAAA 2001:503:a83e::2:30
+b.gtld-servers.net. 172800 IN A 192.33.14.30
+b.gtld-servers.net. 172800 IN AAAA 2001:503:231d::2:30
+c.gtld-servers.net. 172800 IN A 192.26.92.30
+c.gtld-servers.net. 172800 IN AAAA 2001:503:83eb::30
+d.gtld-servers.net. 172800 IN A 192.31.80.30
+d.gtld-servers.net. 172800 IN AAAA 2001:500:856e::30
+e.gtld-servers.net. 172800 IN A 192.12.94.30
+e.gtld-servers.net. 172800 IN AAAA 2001:502:1ca1::30
+f.gtld-servers.net. 172800 IN A 192.35.51.30
+f.gtld-servers.net. 172800 IN AAAA 2001:503:d414::30
+g.gtld-servers.net. 172800 IN A 192.42.93.30
+g.gtld-servers.net. 172800 IN AAAA 2001:503:eea3::30
+h.gtld-servers.net. 172800 IN A 192.54.112.30
+h.gtld-servers.net. 172800 IN AAAA 2001:502:8cc::30
+i.gtld-servers.net. 172800 IN A 192.43.172.30
+i.gtld-servers.net. 172800 IN AAAA 2001:503:39c1::30
+j.gtld-servers.net. 172800 IN A 192.48.79.30
+j.gtld-servers.net. 172800 IN AAAA 2001:502:7094::30
+k.gtld-servers.net. 172800 IN A 192.52.178.30
+k.gtld-servers.net. 172800 IN AAAA 2001:503:d2d::30
+l.gtld-servers.net. 172800 IN A 192.41.162.30
+l.gtld-servers.net. 172800 IN AAAA 2001:500:d937::30
+m.gtld-servers.net. 172800 IN A 192.55.83.30
+m.gtld-servers.net. 172800 IN AAAA 2001:501:b1f9::30
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH subdomain
+ADJUST copy_id copy_query
+REPLY QR RD NOERROR
+SECTION QUESTION
+com. IN NS
+SECTION AUTHORITY
+com. 172800 IN NS a.gtld-servers.net.
+com. 172800 IN NS b.gtld-servers.net.
+com. 172800 IN NS c.gtld-servers.net.
+com. 172800 IN NS d.gtld-servers.net.
+com. 172800 IN NS e.gtld-servers.net.
+com. 172800 IN NS f.gtld-servers.net.
+com. 172800 IN NS g.gtld-servers.net.
+com. 172800 IN NS h.gtld-servers.net.
+com. 172800 IN NS i.gtld-servers.net.
+com. 172800 IN NS j.gtld-servers.net.
+com. 172800 IN NS k.gtld-servers.net.
+com. 172800 IN NS l.gtld-servers.net.
+com. 172800 IN NS m.gtld-servers.net.
+com. 86400 IN DS 30909 8 2 e2d3c916f6deeac73294e8268fb5885044a833fc5459588f4a9184cfc41a5766
+com. 86400 IN RRSIG DS 8 1 86400 20190708050000 20190625040000 25266 . h8CYVMqouUO2IAPlG4Iqf06ykpl07wny KuM2dRGhrfx5hQbF0CpzGRwT2B6i2drI td9i7BSA4GVKLlTYr9n3Xd+BcAHKwywv 44A2WmTAo3xWMv4THwowwu29B4bAKe0V WQKDfmZ92m1yn8T3MCNZWtuGGaLcY6+g fKgyuHu5fEakVn2GFMdAMayBBFTF0bp4 hVFuNSJBe/1EnFZMcxU9aNuCyC8xup25 7K3x1rcM0hthHr8o0Vevpima1YXsWDGb RDIkDyStPDIQ1c0C9LHMaaGR+MA+fxoL 2x4w2lwOptCK//zpfyPvj11oIyouwgdh Fe3PCf9hS03Y1FsiY+mtWw==
+SECTION ADDITIONAL
+a.gtld-servers.net. 172800 IN A 192.5.6.30
+a.gtld-servers.net. 172800 IN AAAA 2001:503:a83e::2:30
+b.gtld-servers.net. 172800 IN A 192.33.14.30
+b.gtld-servers.net. 172800 IN AAAA 2001:503:231d::2:30
+c.gtld-servers.net. 172800 IN A 192.26.92.30
+c.gtld-servers.net. 172800 IN AAAA 2001:503:83eb::30
+d.gtld-servers.net. 172800 IN A 192.31.80.30
+d.gtld-servers.net. 172800 IN AAAA 2001:500:856e::30
+e.gtld-servers.net. 172800 IN A 192.12.94.30
+e.gtld-servers.net. 172800 IN AAAA 2001:502:1ca1::30
+f.gtld-servers.net. 172800 IN A 192.35.51.30
+f.gtld-servers.net. 172800 IN AAAA 2001:503:d414::30
+g.gtld-servers.net. 172800 IN A 192.42.93.30
+g.gtld-servers.net. 172800 IN AAAA 2001:503:eea3::30
+h.gtld-servers.net. 172800 IN A 192.54.112.30
+h.gtld-servers.net. 172800 IN AAAA 2001:502:8cc::30
+i.gtld-servers.net. 172800 IN A 192.43.172.30
+i.gtld-servers.net. 172800 IN AAAA 2001:503:39c1::30
+j.gtld-servers.net. 172800 IN A 192.48.79.30
+j.gtld-servers.net. 172800 IN AAAA 2001:502:7094::30
+k.gtld-servers.net. 172800 IN A 192.52.178.30
+k.gtld-servers.net. 172800 IN AAAA 2001:503:d2d::30
+l.gtld-servers.net. 172800 IN A 192.41.162.30
+l.gtld-servers.net. 172800 IN AAAA 2001:500:d937::30
+m.gtld-servers.net. 172800 IN A 192.55.83.30
+m.gtld-servers.net. 172800 IN AAAA 2001:501:b1f9::30
+ENTRY_END
+
+
+
+
+RANGE_END
+
+
+
+; Group's zones:
+;	cz.
+;	nic.cz.
+; Server names:
+;	a.ns.nic.cz.
+;	b.ns.nic.cz.
+;	c.ns.nic.cz.
+;	d.ns.nic.cz.
+RANGE_BEGIN 0 1000
+	ADDRESS 194.0.14.1
+	ADDRESS 194.0.13.1
+	ADDRESS 193.29.206.1
+	ADDRESS 2001:678:1::1
+	ADDRESS 2001:678:11::1
+	ADDRESS 2001:678:10::1
+	ADDRESS 2001:678:f::1
+	ADDRESS 194.0.12.1
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+ns.nic.cz. IN NS
+SECTION AUTHORITY
+jnp2uc34hha9de64l3rjf6ulp4pra74n.nic.cz. 7200 IN NSEC3 1 0 10 879ec89c91d874a8 jsdlj2k5hipr7eb12ne8bads7lshvo1k
+jnp2uc34hha9de64l3rjf6ulp4pra74n.nic.cz. 7200 IN RRSIG NSEC3 13 3 7200 20190707164247 20190624124001 10486 nic.cz. lrFJPPGpHyoC5l4uM8l94ye/HG1kTVw7 dR98um06iG+2XK82Dib+wnzqoNNIqbaA FeaAkjfqgCHA8kDySAP+5g==
+nic.cz. 1800 IN RRSIG SOA 13 2 1800 20190708100906 20190624124001 10486 nic.cz. 1mDJpihqjobv42BXF8H1dT0/vLtPTpb/ k7flS9wr8tEPe57o6GrkimcSWZlS/lm5 OyhvjIpvU9Da8n2ezGiGHw==
+nic.cz. 1800 IN SOA a.ns.nic.cz. hostmaster.nic.cz. 1561383601 10800 3600 1209600 7200
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+b.ns.nic.cz. IN A
+SECTION ANSWER
+b.ns.nic.cz. 1800 IN A 194.0.13.1
+b.ns.nic.cz. 1800 IN RRSIG A 13 4 1800 20190708030702 20190624124001 10486 nic.cz. bV+9iqB6KDNUCZrcoo9fXj3X1BHhCpgh MGSXx8q4JWJ9mm9Hz6h63UfXTWPthvJy +J18PantZQVPScwMoXVzuw==
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+nic.cz. IN DNSKEY
+SECTION ANSWER
+nic.cz. 1800 IN DNSKEY 256 3 13 SmMYG4VjCgj4rAxB4sqgvIzcGtESoX1H m7Dsoekap6HJwj8WOEiFciSg537caOPl 4+7Dyp/b5JwkBemxQQRL9Q==
+nic.cz. 1800 IN DNSKEY 257 3 13 LM4zvjUgZi2XZKsYooDE0HFYGfWp242f KB+O8sLsuox8S6MJTowY8lBDjZD7JKbm aNot3+1H8zU9TrDzWmmHwQ==
+nic.cz. 1800 IN RRSIG DNSKEY 13 2 1800 20190707163411 20190624124001 61281 nic.cz. ggHlmuzLOTZOCYcbZ8TrNoTXOAg7xJ9N B+QLdmZYyny53ODMkRfDv28SSMkwtuc1 rZXfC+/c7oArzsBbbncTRA==
+nic.cz. 1800 IN RRSIG DNSKEY 13 2 1800 20190708092836 20190624124001 10486 nic.cz. lFYLLcm5ICS0BSdB0+dA8m7XxdRbB49+ 5N1w8AHOaPNDTWp9GlXA935IUk18C2to 1ghYmP2RZaNOTchSVRgWzA==
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+b.ns.nic.cz. IN A
+SECTION ANSWER
+b.ns.nic.cz. 1800 IN A 194.0.13.1
+b.ns.nic.cz. 1800 IN RRSIG A 13 4 1800 20190708030702 20190624124001 10486 nic.cz. bV+9iqB6KDNUCZrcoo9fXj3X1BHhCpgh MGSXx8q4JWJ9mm9Hz6h63UfXTWPthvJy +J18PantZQVPScwMoXVzuw==
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+b.ns.nic.cz. IN AAAA
+SECTION ANSWER
+b.ns.nic.cz. 1800 IN AAAA 2001:678:10::1
+b.ns.nic.cz. 1800 IN RRSIG AAAA 13 4 1800 20190707133636 20190624124001 10486 nic.cz. OuH2sPy1tH6CENbjioxaaYzCB8yxB1sP FyQXAcY4VpNmLnqthfGKTn5dONZuG4UD I9ihrEaPsV3RsDse0GpMqg==
+SECTION AUTHORITY
+nic.cz. 1800 IN NS a.ns.nic.cz.
+nic.cz. 1800 IN NS b.ns.nic.cz.
+nic.cz. 1800 IN NS d.ns.nic.cz.
+nic.cz. 1800 IN RRSIG NS 13 2 1800 20190707221726 20190624124001 10486 nic.cz. JhCrQB0nVFkti/j3weaalBPxqDG7PyiC KLV7hj61SLdRGcue9/fI9IN7lIanFWhL A1b7/L5DYejIY7WpHVU3Jg==
+SECTION ADDITIONAL
+a.ns.nic.cz. 1800 IN A 194.0.12.1
+a.ns.nic.cz. 1800 IN AAAA 2001:678:f::1
+a.ns.nic.cz. 1800 IN RRSIG A 13 4 1800 20190708050633 20190624124001 10486 nic.cz. 18u1P3Wvg0xoz3fTRtqVNlTHiZPOuGW7 C8nsMIBTCTT9mPYN0z+CcBDfRwVLNnfJ eNTfHXA9zERxbAT3WCHEXg==
+a.ns.nic.cz. 1800 IN RRSIG AAAA 13 4 1800 20190707232622 20190624124001 10486 nic.cz. qY1Rm171qERHJwykmMYDKXlIGUnHdMhX gYlvOZPGONNuapbsqzTQos9Vd7v4IQfp k6j8sVTjSId1/q/75D4vNQ==
+b.ns.nic.cz. 1800 IN A 194.0.13.1
+b.ns.nic.cz. 1800 IN RRSIG A 13 4 1800 20190708030702 20190624124001 10486 nic.cz. bV+9iqB6KDNUCZrcoo9fXj3X1BHhCpgh MGSXx8q4JWJ9mm9Hz6h63UfXTWPthvJy +J18PantZQVPScwMoXVzuw==
+d.ns.nic.cz. 1800 IN A 193.29.206.1
+d.ns.nic.cz. 1800 IN AAAA 2001:678:1::1
+d.ns.nic.cz. 1800 IN RRSIG A 13 4 1800 20190708114823 20190624124001 10486 nic.cz. p2nhRTWBo56GXRdL19wT+y/XyNb6wjrz Oy3AndSR2/L9BDZrX/mkGYh20x5KpdUV +r+DPy9XFXEmvGrwAD5meA==
+d.ns.nic.cz. 1800 IN RRSIG AAAA 13 4 1800 20190708121635 20190624124001 10486 nic.cz. QeqTWoaOuL+L+QdiGOIne/WCi+D0V6EH 0h96aDuMs2eySLXSWPC54ICz28gwudmh wX4oEdQf1nYVneO7iEDFew==
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+c.ns.nic.cz. IN A
+SECTION ANSWER
+c.ns.nic.cz. 1800 IN A 194.0.14.1
+c.ns.nic.cz. 1800 IN RRSIG A 13 4 1800 20190708123232 20190624124001 10486 nic.cz. ln7Q9H73Ba6dEbIrhA6QrK3OMMEIu4QA h4fJ3xeUIW4US+XU21wylj09Zaf6ALE+ V3E9jTWdPfo1UTGnuW1VUw==
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+d.ns.nic.cz. IN AAAA
+SECTION ANSWER
+d.ns.nic.cz. 1800 IN AAAA 2001:678:1::1
+d.ns.nic.cz. 1800 IN RRSIG AAAA 13 4 1800 20190708121635 20190624124001 10486 nic.cz. QeqTWoaOuL+L+QdiGOIne/WCi+D0V6EH 0h96aDuMs2eySLXSWPC54ICz28gwudmh wX4oEdQf1nYVneO7iEDFew==
+SECTION AUTHORITY
+nic.cz. 1800 IN NS a.ns.nic.cz.
+nic.cz. 1800 IN NS b.ns.nic.cz.
+nic.cz. 1800 IN NS d.ns.nic.cz.
+nic.cz. 1800 IN RRSIG NS 13 2 1800 20190707221726 20190624124001 10486 nic.cz. JhCrQB0nVFkti/j3weaalBPxqDG7PyiC KLV7hj61SLdRGcue9/fI9IN7lIanFWhL A1b7/L5DYejIY7WpHVU3Jg==
+SECTION ADDITIONAL
+a.ns.nic.cz. 1800 IN A 194.0.12.1
+a.ns.nic.cz. 1800 IN AAAA 2001:678:f::1
+a.ns.nic.cz. 1800 IN RRSIG A 13 4 1800 20190708050633 20190624124001 10486 nic.cz. 18u1P3Wvg0xoz3fTRtqVNlTHiZPOuGW7 C8nsMIBTCTT9mPYN0z+CcBDfRwVLNnfJ eNTfHXA9zERxbAT3WCHEXg==
+a.ns.nic.cz. 1800 IN RRSIG AAAA 13 4 1800 20190707232622 20190624124001 10486 nic.cz. qY1Rm171qERHJwykmMYDKXlIGUnHdMhX gYlvOZPGONNuapbsqzTQos9Vd7v4IQfp k6j8sVTjSId1/q/75D4vNQ==
+b.ns.nic.cz. 1800 IN A 194.0.13.1
+b.ns.nic.cz. 1800 IN AAAA 2001:678:10::1
+b.ns.nic.cz. 1800 IN RRSIG A 13 4 1800 20190708030702 20190624124001 10486 nic.cz. bV+9iqB6KDNUCZrcoo9fXj3X1BHhCpgh MGSXx8q4JWJ9mm9Hz6h63UfXTWPthvJy +J18PantZQVPScwMoXVzuw==
+b.ns.nic.cz. 1800 IN RRSIG AAAA 13 4 1800 20190707133636 20190624124001 10486 nic.cz. OuH2sPy1tH6CENbjioxaaYzCB8yxB1sP FyQXAcY4VpNmLnqthfGKTn5dONZuG4UD I9ihrEaPsV3RsDse0GpMqg==
+d.ns.nic.cz. 1800 IN A 193.29.206.1
+d.ns.nic.cz. 1800 IN RRSIG A 13 4 1800 20190708114823 20190624124001 10486 nic.cz. p2nhRTWBo56GXRdL19wT+y/XyNb6wjrz Oy3AndSR2/L9BDZrX/mkGYh20x5KpdUV +r+DPy9XFXEmvGrwAD5meA==
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+b.ns.nic.cz. IN AAAA
+SECTION ANSWER
+b.ns.nic.cz. 1800 IN AAAA 2001:678:10::1
+b.ns.nic.cz. 1800 IN RRSIG AAAA 13 4 1800 20190707133636 20190624124001 10486 nic.cz. OuH2sPy1tH6CENbjioxaaYzCB8yxB1sP FyQXAcY4VpNmLnqthfGKTn5dONZuG4UD I9ihrEaPsV3RsDse0GpMqg==
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+a.ns.nic.cz. IN NS
+SECTION AUTHORITY
+51npp2qit2otcucer39ql8d4q4h9mr5d.nic.cz. 7200 IN NSEC3 1 0 10 879ec89c91d874a8 52jm0s7pifluesur7b9p840f8fkcpcsi A AAAA RRSIG
+51npp2qit2otcucer39ql8d4q4h9mr5d.nic.cz. 7200 IN RRSIG NSEC3 13 3 7200 20190708102945 20190624124001 10486 nic.cz. ScbUA0IlzL0o1h34t007ViOD53YFHe+V zn2ge8gqiNeT29FW/sCwiyVsrUpMZ7nW O9gmXfdNjjtmyTA7iWbVTA==
+nic.cz. 1800 IN RRSIG SOA 13 2 1800 20190708100906 20190624124001 10486 nic.cz. 1mDJpihqjobv42BXF8H1dT0/vLtPTpb/ k7flS9wr8tEPe57o6GrkimcSWZlS/lm5 OyhvjIpvU9Da8n2ezGiGHw==
+nic.cz. 1800 IN SOA a.ns.nic.cz. hostmaster.nic.cz. 1561383601 10800 3600 1209600 7200
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+c.ns.nic.cz. IN A
+SECTION ANSWER
+c.ns.nic.cz. 1800 IN A 194.0.14.1
+c.ns.nic.cz. 1800 IN RRSIG A 13 4 1800 20190708123232 20190624124001 10486 nic.cz. ln7Q9H73Ba6dEbIrhA6QrK3OMMEIu4QA h4fJ3xeUIW4US+XU21wylj09Zaf6ALE+ V3E9jTWdPfo1UTGnuW1VUw==
+SECTION AUTHORITY
+nic.cz. 1800 IN NS a.ns.nic.cz.
+nic.cz. 1800 IN NS b.ns.nic.cz.
+nic.cz. 1800 IN NS d.ns.nic.cz.
+nic.cz. 1800 IN RRSIG NS 13 2 1800 20190707221726 20190624124001 10486 nic.cz. JhCrQB0nVFkti/j3weaalBPxqDG7PyiC KLV7hj61SLdRGcue9/fI9IN7lIanFWhL A1b7/L5DYejIY7WpHVU3Jg==
+SECTION ADDITIONAL
+a.ns.nic.cz. 1800 IN A 194.0.12.1
+a.ns.nic.cz. 1800 IN AAAA 2001:678:f::1
+a.ns.nic.cz. 1800 IN RRSIG A 13 4 1800 20190708050633 20190624124001 10486 nic.cz. 18u1P3Wvg0xoz3fTRtqVNlTHiZPOuGW7 C8nsMIBTCTT9mPYN0z+CcBDfRwVLNnfJ eNTfHXA9zERxbAT3WCHEXg==
+a.ns.nic.cz. 1800 IN RRSIG AAAA 13 4 1800 20190707232622 20190624124001 10486 nic.cz. qY1Rm171qERHJwykmMYDKXlIGUnHdMhX gYlvOZPGONNuapbsqzTQos9Vd7v4IQfp k6j8sVTjSId1/q/75D4vNQ==
+b.ns.nic.cz. 1800 IN A 194.0.13.1
+b.ns.nic.cz. 1800 IN AAAA 2001:678:10::1
+b.ns.nic.cz. 1800 IN RRSIG A 13 4 1800 20190708030702 20190624124001 10486 nic.cz. bV+9iqB6KDNUCZrcoo9fXj3X1BHhCpgh MGSXx8q4JWJ9mm9Hz6h63UfXTWPthvJy +J18PantZQVPScwMoXVzuw==
+b.ns.nic.cz. 1800 IN RRSIG AAAA 13 4 1800 20190707133636 20190624124001 10486 nic.cz. OuH2sPy1tH6CENbjioxaaYzCB8yxB1sP FyQXAcY4VpNmLnqthfGKTn5dONZuG4UD I9ihrEaPsV3RsDse0GpMqg==
+d.ns.nic.cz. 1800 IN A 193.29.206.1
+d.ns.nic.cz. 1800 IN AAAA 2001:678:1::1
+d.ns.nic.cz. 1800 IN RRSIG A 13 4 1800 20190708114823 20190624124001 10486 nic.cz. p2nhRTWBo56GXRdL19wT+y/XyNb6wjrz Oy3AndSR2/L9BDZrX/mkGYh20x5KpdUV +r+DPy9XFXEmvGrwAD5meA==
+d.ns.nic.cz. 1800 IN RRSIG AAAA 13 4 1800 20190708121635 20190624124001 10486 nic.cz. QeqTWoaOuL+L+QdiGOIne/WCi+D0V6EH 0h96aDuMs2eySLXSWPC54ICz28gwudmh wX4oEdQf1nYVneO7iEDFew==
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+nic.cz. IN DS
+SECTION ANSWER
+nic.cz. 3600 IN DS 61281 13 2 4104d40c8fe2030bf7a09a199fcf37b36f7ec8ddd16f5a84f2e61c248d3afd0f
+nic.cz. 3600 IN RRSIG DS 13 2 3600 20190705064642 20190622210528 6318 cz. h4tSy9MopxkbCg2mPu0s/CoE+DtoKUTL 5iw1cpQZOF1MJMZhTYo3yZjYiIkIrih8 xigA0UNFXtZEAxzsqI6omA==
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+c.ns.nic.cz. IN AAAA
+SECTION ANSWER
+c.ns.nic.cz. 1800 IN AAAA 2001:678:11::1
+c.ns.nic.cz. 1800 IN RRSIG AAAA 13 4 1800 20190707153808 20190624124001 10486 nic.cz. 2n+SYd+Eh6pFujzSb5u/ZFbJkfHGB3aB wo5vSKAp+s8RgEtwMawcs54psA6LWKc5 swrxP1C1xVyMLQ6L7eifGA==
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+a.ns.nic.cz. IN AAAA
+SECTION ANSWER
+a.ns.nic.cz. 1800 IN AAAA 2001:678:f::1
+a.ns.nic.cz. 1800 IN RRSIG AAAA 13 4 1800 20190707232622 20190624124001 10486 nic.cz. qY1Rm171qERHJwykmMYDKXlIGUnHdMhX gYlvOZPGONNuapbsqzTQos9Vd7v4IQfp k6j8sVTjSId1/q/75D4vNQ==
+SECTION AUTHORITY
+nic.cz. 1800 IN NS a.ns.nic.cz.
+nic.cz. 1800 IN NS b.ns.nic.cz.
+nic.cz. 1800 IN NS d.ns.nic.cz.
+nic.cz. 1800 IN RRSIG NS 13 2 1800 20190707221726 20190624124001 10486 nic.cz. JhCrQB0nVFkti/j3weaalBPxqDG7PyiC KLV7hj61SLdRGcue9/fI9IN7lIanFWhL A1b7/L5DYejIY7WpHVU3Jg==
+SECTION ADDITIONAL
+a.ns.nic.cz. 1800 IN A 194.0.12.1
+a.ns.nic.cz. 1800 IN RRSIG A 13 4 1800 20190708050633 20190624124001 10486 nic.cz. 18u1P3Wvg0xoz3fTRtqVNlTHiZPOuGW7 C8nsMIBTCTT9mPYN0z+CcBDfRwVLNnfJ eNTfHXA9zERxbAT3WCHEXg==
+b.ns.nic.cz. 1800 IN A 194.0.13.1
+b.ns.nic.cz. 1800 IN AAAA 2001:678:10::1
+b.ns.nic.cz. 1800 IN RRSIG A 13 4 1800 20190708030702 20190624124001 10486 nic.cz. bV+9iqB6KDNUCZrcoo9fXj3X1BHhCpgh MGSXx8q4JWJ9mm9Hz6h63UfXTWPthvJy +J18PantZQVPScwMoXVzuw==
+b.ns.nic.cz. 1800 IN RRSIG AAAA 13 4 1800 20190707133636 20190624124001 10486 nic.cz. OuH2sPy1tH6CENbjioxaaYzCB8yxB1sP FyQXAcY4VpNmLnqthfGKTn5dONZuG4UD I9ihrEaPsV3RsDse0GpMqg==
+d.ns.nic.cz. 1800 IN A 193.29.206.1
+d.ns.nic.cz. 1800 IN AAAA 2001:678:1::1
+d.ns.nic.cz. 1800 IN RRSIG A 13 4 1800 20190708114823 20190624124001 10486 nic.cz. p2nhRTWBo56GXRdL19wT+y/XyNb6wjrz Oy3AndSR2/L9BDZrX/mkGYh20x5KpdUV +r+DPy9XFXEmvGrwAD5meA==
+d.ns.nic.cz. 1800 IN RRSIG AAAA 13 4 1800 20190708121635 20190624124001 10486 nic.cz. QeqTWoaOuL+L+QdiGOIne/WCi+D0V6EH 0h96aDuMs2eySLXSWPC54ICz28gwudmh wX4oEdQf1nYVneO7iEDFew==
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+c.ns.nic.cz. IN NS
+SECTION AUTHORITY
+CNTVMLLA2O27TCBC4MEP7IV9P54L7FLE.nic.cz. 7200 IN NSEC3 1 0 10 879ec89c91d874a8 co07u5iiiqhl96t3hlmgkchj3203eqqj A AAAA RRSIG
+CNTVMLLA2O27TCBC4MEP7IV9P54L7FLE.nic.cz. 7200 IN RRSIG NSEC3 13 3 7200 20190707155010 20190624124001 10486 nic.cz. osfB/CgwWbwa/BX/fYo+gzrImuam0bhT bD9xmAH6w+acJ8GrCNHNcCgFdimdacEA rSx2ztVVWCiALLlqzFP1WQ==
+nic.cz. 1800 IN RRSIG SOA 13 2 1800 20190708100906 20190624124001 10486 nic.cz. 1mDJpihqjobv42BXF8H1dT0/vLtPTpb/ k7flS9wr8tEPe57o6GrkimcSWZlS/lm5 OyhvjIpvU9Da8n2ezGiGHw==
+nic.cz. 1800 IN SOA a.ns.nic.cz. hostmaster.nic.cz. 1561383601 10800 3600 1209600 7200
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+d.ns.nic.cz. IN A
+SECTION ANSWER
+d.ns.nic.cz. 1800 IN A 193.29.206.1
+d.ns.nic.cz. 1800 IN RRSIG A 13 4 1800 20190708114823 20190624124001 10486 nic.cz. p2nhRTWBo56GXRdL19wT+y/XyNb6wjrz Oy3AndSR2/L9BDZrX/mkGYh20x5KpdUV +r+DPy9XFXEmvGrwAD5meA==
+SECTION AUTHORITY
+nic.cz. 1800 IN NS a.ns.nic.cz.
+nic.cz. 1800 IN NS b.ns.nic.cz.
+nic.cz. 1800 IN NS d.ns.nic.cz.
+nic.cz. 1800 IN RRSIG NS 13 2 1800 20190707221726 20190624124001 10486 nic.cz. JhCrQB0nVFkti/j3weaalBPxqDG7PyiC KLV7hj61SLdRGcue9/fI9IN7lIanFWhL A1b7/L5DYejIY7WpHVU3Jg==
+SECTION ADDITIONAL
+a.ns.nic.cz. 1800 IN A 194.0.12.1
+a.ns.nic.cz. 1800 IN AAAA 2001:678:f::1
+a.ns.nic.cz. 1800 IN RRSIG A 13 4 1800 20190708050633 20190624124001 10486 nic.cz. 18u1P3Wvg0xoz3fTRtqVNlTHiZPOuGW7 C8nsMIBTCTT9mPYN0z+CcBDfRwVLNnfJ eNTfHXA9zERxbAT3WCHEXg==
+a.ns.nic.cz. 1800 IN RRSIG AAAA 13 4 1800 20190707232622 20190624124001 10486 nic.cz. qY1Rm171qERHJwykmMYDKXlIGUnHdMhX gYlvOZPGONNuapbsqzTQos9Vd7v4IQfp k6j8sVTjSId1/q/75D4vNQ==
+b.ns.nic.cz. 1800 IN A 194.0.13.1
+b.ns.nic.cz. 1800 IN AAAA 2001:678:10::1
+b.ns.nic.cz. 1800 IN RRSIG A 13 4 1800 20190708030702 20190624124001 10486 nic.cz. bV+9iqB6KDNUCZrcoo9fXj3X1BHhCpgh MGSXx8q4JWJ9mm9Hz6h63UfXTWPthvJy +J18PantZQVPScwMoXVzuw==
+b.ns.nic.cz. 1800 IN RRSIG AAAA 13 4 1800 20190707133636 20190624124001 10486 nic.cz. OuH2sPy1tH6CENbjioxaaYzCB8yxB1sP FyQXAcY4VpNmLnqthfGKTn5dONZuG4UD I9ihrEaPsV3RsDse0GpMqg==
+d.ns.nic.cz. 1800 IN AAAA 2001:678:1::1
+d.ns.nic.cz. 1800 IN RRSIG AAAA 13 4 1800 20190708121635 20190624124001 10486 nic.cz. QeqTWoaOuL+L+QdiGOIne/WCi+D0V6EH 0h96aDuMs2eySLXSWPC54ICz28gwudmh wX4oEdQf1nYVneO7iEDFew==
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+nic.cz. IN DNSKEY
+SECTION ANSWER
+nic.cz. 1800 IN DNSKEY 256 3 13 SmMYG4VjCgj4rAxB4sqgvIzcGtESoX1H m7Dsoekap6HJwj8WOEiFciSg537caOPl 4+7Dyp/b5JwkBemxQQRL9Q==
+nic.cz. 1800 IN DNSKEY 257 3 13 LM4zvjUgZi2XZKsYooDE0HFYGfWp242f KB+O8sLsuox8S6MJTowY8lBDjZD7JKbm aNot3+1H8zU9TrDzWmmHwQ==
+nic.cz. 1800 IN RRSIG DNSKEY 13 2 1800 20190707163411 20190624124001 61281 nic.cz. ggHlmuzLOTZOCYcbZ8TrNoTXOAg7xJ9N B+QLdmZYyny53ODMkRfDv28SSMkwtuc1 rZXfC+/c7oArzsBbbncTRA==
+nic.cz. 1800 IN RRSIG DNSKEY 13 2 1800 20190708092836 20190624124001 10486 nic.cz. lFYLLcm5ICS0BSdB0+dA8m7XxdRbB49+ 5N1w8AHOaPNDTWp9GlXA935IUk18C2to 1ghYmP2RZaNOTchSVRgWzA==
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+c.ns.nic.cz. IN NS
+SECTION AUTHORITY
+cntvmlla2o27tcbc4mep7iv9p54l7fle.nic.cz. 7200 IN NSEC3 1 0 10 879ec89c91d874a8 co07u5iiiqhl96t3hlmgkchj3203eqqj A AAAA RRSIG
+cntvmlla2o27tcbc4mep7iv9p54l7fle.nic.cz. 7200 IN RRSIG NSEC3 13 3 7200 20190707155010 20190624124001 10486 nic.cz. osfB/CgwWbwa/BX/fYo+gzrImuam0bhT bD9xmAH6w+acJ8GrCNHNcCgFdimdacEA rSx2ztVVWCiALLlqzFP1WQ==
+nic.cz. 1800 IN RRSIG SOA 13 2 1800 20190708100906 20190624124001 10486 nic.cz. 1mDJpihqjobv42BXF8H1dT0/vLtPTpb/ k7flS9wr8tEPe57o6GrkimcSWZlS/lm5 OyhvjIpvU9Da8n2ezGiGHw==
+nic.cz. 1800 IN SOA a.ns.nic.cz. hostmaster.nic.cz. 1561383601 10800 3600 1209600 7200
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+b.ns.nic.cz. IN NS
+SECTION AUTHORITY
+cu82t3qracdj063olk907dv20ine9dea.nic.cz. 7200 IN NSEC3 1 0 10 879ec89c91d874a8 d2749lueihj9moq02lt0k9i8tnbgest1 A AAAA RRSIG
+cu82t3qracdj063olk907dv20ine9dea.nic.cz. 7200 IN RRSIG NSEC3 13 3 7200 20190708122905 20190624124001 10486 nic.cz. fg5ypFDXqZlnzSbndkPm2VjZieL0t5NT zKu0cfcWHu4TlWB/OxxuaD4C2oGx5nki Pchj+FQNobNZJfCXKOa4ug==
+nic.cz. 1800 IN RRSIG SOA 13 2 1800 20190708100906 20190624124001 10486 nic.cz. 1mDJpihqjobv42BXF8H1dT0/vLtPTpb/ k7flS9wr8tEPe57o6GrkimcSWZlS/lm5 OyhvjIpvU9Da8n2ezGiGHw==
+nic.cz. 1800 IN SOA a.ns.nic.cz. hostmaster.nic.cz. 1561383601 10800 3600 1209600 7200
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+csas.cz. IN DS
+SECTION ANSWER
+csas.cz. 3600 IN DS 8196 7 2 c5c7974e1dc3bf036f8744a4d919e03ef01d8d6167db6201940ca87059558ee3
+csas.cz. 3600 IN RRSIG DS 13 2 3600 20190706080140 20190622110535 6318 cz. 5V0ZvjpT8zWMsVwPpyhsMc9DRFVMQtP2 D2o7S/dLbZ7YL4Mqd8P9n+o+4NQgaqQw 7VPBHnN3VzVDYvWjmr+rfw==
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+ns.nic.cz. IN NS
+SECTION AUTHORITY
+JNP2UC34HHA9DE64L3RJF6ULP4PRA74N.nic.cz. 7200 IN NSEC3 1 0 10 879ec89c91d874a8 jsdlj2k5hipr7eb12ne8bads7lshvo1k
+JNP2UC34HHA9DE64L3RJF6ULP4PRA74N.nic.cz. 7200 IN RRSIG NSEC3 13 3 7200 20190707164247 20190624124001 10486 nic.cz. lrFJPPGpHyoC5l4uM8l94ye/HG1kTVw7 dR98um06iG+2XK82Dib+wnzqoNNIqbaA FeaAkjfqgCHA8kDySAP+5g==
+nic.cz. 1800 IN RRSIG SOA 13 2 1800 20190708100906 20190624124001 10486 nic.cz. 1mDJpihqjobv42BXF8H1dT0/vLtPTpb/ k7flS9wr8tEPe57o6GrkimcSWZlS/lm5 OyhvjIpvU9Da8n2ezGiGHw==
+nic.cz. 1800 IN SOA a.ns.nic.cz. hostmaster.nic.cz. 1561383601 10800 3600 1209600 7200
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+d.ns.nic.cz. IN NS
+SECTION AUTHORITY
+nic.cz. 1800 IN RRSIG SOA 13 2 1800 20190708100906 20190624124001 10486 nic.cz. 1mDJpihqjobv42BXF8H1dT0/vLtPTpb/ k7flS9wr8tEPe57o6GrkimcSWZlS/lm5 OyhvjIpvU9Da8n2ezGiGHw==
+nic.cz. 1800 IN SOA a.ns.nic.cz. hostmaster.nic.cz. 1561383601 10800 3600 1209600 7200
+on20qsre8qs9a2asfdatp5cs6g2i5ssq.nic.cz. 7200 IN NSEC3 1 0 10 879ec89c91d874a8 onv9qnjm1krm9qdk0n6o6o23doo5jfug A AAAA RRSIG
+on20qsre8qs9a2asfdatp5cs6g2i5ssq.nic.cz. 7200 IN RRSIG NSEC3 13 3 7200 20190708041440 20190624124001 10486 nic.cz. WkMEKZUDwPTv5Y3KG/C9LTVTynACPb16 1OuoxTij1reZR4LzHVoGQKDf0Dbj2Rau 9LrBW5PI5PSDQ6BmUKRj6A==
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+a.ns.nic.cz. IN AAAA
+SECTION ANSWER
+a.ns.nic.cz. 1800 IN AAAA 2001:678:f::1
+a.ns.nic.cz. 1800 IN RRSIG AAAA 13 4 1800 20190707232622 20190624124001 10486 nic.cz. qY1Rm171qERHJwykmMYDKXlIGUnHdMhX gYlvOZPGONNuapbsqzTQos9Vd7v4IQfp k6j8sVTjSId1/q/75D4vNQ==
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+a.ns.nic.cz. IN A
+SECTION ANSWER
+a.ns.nic.cz. 1800 IN A 194.0.12.1
+a.ns.nic.cz. 1800 IN RRSIG A 13 4 1800 20190708050633 20190624124001 10486 nic.cz. 18u1P3Wvg0xoz3fTRtqVNlTHiZPOuGW7 C8nsMIBTCTT9mPYN0z+CcBDfRwVLNnfJ eNTfHXA9zERxbAT3WCHEXg==
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+cz. IN DS
+SECTION AUTHORITY
+cz. 3600 IN RRSIG SOA 13 1 3600 20190707192652 20190625123528 6318 cz. BYXtAj/BIXIb5xlT6TBQYaFhbloeuo0H RqJTdPu9gVVyuBKbvV6YmQbS4BBMM4qA Cp2Vw7yBK9+dONHp9JAmuA==
+cz. 3600 IN SOA a.ns.nic.cz. hostmaster.nic.cz. 1561469728 900 300 604800 900
+fu65o5n6kmh8a04mps1e4a73s37jr72u.cz. 900 IN NSEC3 1 0 10 357dda080afe0ef8 fu677p5qqp6ihbeeloacm3sr4ieklu7m NS SOA RRSIG DNSKEY NSEC3PARAM
+fu65o5n6kmh8a04mps1e4a73s37jr72u.cz. 900 IN RRSIG NSEC3 13 2 900 20190706134746 20190622170523 6318 cz. EsElag8LQ5TcunX40efTh35IN3GoQnPq XAZZ0cSPHT6GOohzp8iD1LSLLbwZUiNE yB4hCp1yqEi0pINRoHglNA==
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+cz. IN DNSKEY
+SECTION ANSWER
+cz. 18000 IN DNSKEY 256 3 13 7t+ZoZGIrV27M/PEAH8OKSjEXVAJhV6O o5ESS+Vry5ZhfoWogIKAXzvda/qY/WTA L09BEk+ko16oGRRktvzWEw==
+cz. 18000 IN DNSKEY 257 3 13 nqzH7xP1QU5UOVy/VvxFSlrB/XgX9JDJ zj51PzIj35TXjZTyalTlAT/f7PAfaSD5 mEG1N8Vk9NmI2nxgQqhzDQ==
+cz. 18000 IN RRSIG DNSKEY 13 1 18000 20190705000000 20190621000000 20237 cz. kJ1zRR76FpPS4SLyFuLbrQBvVnq6GY+x 5sOV2ayq6rt4D1sjpxROufFfBfi/6wAv qo3VZ0iUJSB03djeX8gk5A==
+cz. 18000 IN RRSIG DNSKEY 13 1 18000 20190709092856 20190625123528 6318 cz. Lpz5UZi8lVH1TCdz6DyjWvoUciOVqA4Z d+3TVxNF2GsLzM15nwc34FnaQF3dxhJZ mdf6dET7iOUmy2SN3majVg==
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+c.ns.nic.cz. IN AAAA
+SECTION ANSWER
+c.ns.nic.cz. 1800 IN AAAA 2001:678:11::1
+c.ns.nic.cz. 1800 IN RRSIG AAAA 13 4 1800 20190707153808 20190624124001 10486 nic.cz. 2n+SYd+Eh6pFujzSb5u/ZFbJkfHGB3aB wo5vSKAp+s8RgEtwMawcs54psA6LWKc5 swrxP1C1xVyMLQ6L7eifGA==
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+d.ns.nic.cz. IN A
+SECTION ANSWER
+d.ns.nic.cz. 1800 IN A 193.29.206.1
+d.ns.nic.cz. 1800 IN RRSIG A 13 4 1800 20190708114823 20190624124001 10486 nic.cz. p2nhRTWBo56GXRdL19wT+y/XyNb6wjrz Oy3AndSR2/L9BDZrX/mkGYh20x5KpdUV +r+DPy9XFXEmvGrwAD5meA==
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+d.ns.nic.cz. IN AAAA
+SECTION ANSWER
+d.ns.nic.cz. 1800 IN AAAA 2001:678:1::1
+d.ns.nic.cz. 1800 IN RRSIG AAAA 13 4 1800 20190708121635 20190624124001 10486 nic.cz. QeqTWoaOuL+L+QdiGOIne/WCi+D0V6EH 0h96aDuMs2eySLXSWPC54ICz28gwudmh wX4oEdQf1nYVneO7iEDFew==
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH subdomain
+ADJUST copy_id copy_query
+REPLY QR RD NOERROR
+SECTION QUESTION
+csas.cz. IN NS
+SECTION AUTHORITY
+csas.cz. 3600 IN DS 8196 7 2 c5c7974e1dc3bf036f8744a4d919e03ef01d8d6167db6201940ca87059558ee3
+csas.cz. 3600 IN NS ddnsa.csas.cz.
+csas.cz. 3600 IN NS ddnsb.csas.cz.
+csas.cz. 3600 IN RRSIG DS 13 2 3600 20190706080140 20190622110535 6318 cz. 5V0ZvjpT8zWMsVwPpyhsMc9DRFVMQtP2 D2o7S/dLbZ7YL4Mqd8P9n+o+4NQgaqQw 7VPBHnN3VzVDYvWjmr+rfw==
+SECTION ADDITIONAL
+ddnsa.csas.cz. 3600 IN A 194.50.240.64
+ddnsb.csas.cz. 3600 IN A 194.50.240.192
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH subdomain
+ADJUST copy_id copy_query
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+nic.cz. IN NS
+SECTION ANSWER
+nic.cz. 1800 IN NS a.ns.nic.cz.
+nic.cz. 1800 IN NS b.ns.nic.cz.
+nic.cz. 1800 IN NS d.ns.nic.cz.
+nic.cz. 1800 IN RRSIG NS 13 2 1800 20190707221726 20190624124001 10486 nic.cz. JhCrQB0nVFkti/j3weaalBPxqDG7PyiC KLV7hj61SLdRGcue9/fI9IN7lIanFWhL A1b7/L5DYejIY7WpHVU3Jg==
+SECTION ADDITIONAL
+a.ns.nic.cz. 1800 IN A 194.0.12.1
+a.ns.nic.cz. 1800 IN AAAA 2001:678:f::1
+a.ns.nic.cz. 1800 IN RRSIG A 13 4 1800 20190708050633 20190624124001 10486 nic.cz. 18u1P3Wvg0xoz3fTRtqVNlTHiZPOuGW7 C8nsMIBTCTT9mPYN0z+CcBDfRwVLNnfJ eNTfHXA9zERxbAT3WCHEXg==
+a.ns.nic.cz. 1800 IN RRSIG AAAA 13 4 1800 20190707232622 20190624124001 10486 nic.cz. qY1Rm171qERHJwykmMYDKXlIGUnHdMhX gYlvOZPGONNuapbsqzTQos9Vd7v4IQfp k6j8sVTjSId1/q/75D4vNQ==
+b.ns.nic.cz. 1800 IN A 194.0.13.1
+b.ns.nic.cz. 1800 IN AAAA 2001:678:10::1
+b.ns.nic.cz. 1800 IN RRSIG A 13 4 1800 20190708030702 20190624124001 10486 nic.cz. bV+9iqB6KDNUCZrcoo9fXj3X1BHhCpgh MGSXx8q4JWJ9mm9Hz6h63UfXTWPthvJy +J18PantZQVPScwMoXVzuw==
+b.ns.nic.cz. 1800 IN RRSIG AAAA 13 4 1800 20190707133636 20190624124001 10486 nic.cz. OuH2sPy1tH6CENbjioxaaYzCB8yxB1sP FyQXAcY4VpNmLnqthfGKTn5dONZuG4UD I9ihrEaPsV3RsDse0GpMqg==
+d.ns.nic.cz. 1800 IN A 193.29.206.1
+d.ns.nic.cz. 1800 IN AAAA 2001:678:1::1
+d.ns.nic.cz. 1800 IN RRSIG A 13 4 1800 20190708114823 20190624124001 10486 nic.cz. p2nhRTWBo56GXRdL19wT+y/XyNb6wjrz Oy3AndSR2/L9BDZrX/mkGYh20x5KpdUV +r+DPy9XFXEmvGrwAD5meA==
+d.ns.nic.cz. 1800 IN RRSIG AAAA 13 4 1800 20190708121635 20190624124001 10486 nic.cz. QeqTWoaOuL+L+QdiGOIne/WCi+D0V6EH 0h96aDuMs2eySLXSWPC54ICz28gwudmh wX4oEdQf1nYVneO7iEDFew==
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH subdomain
+ADJUST copy_id copy_query
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+cz. IN NS
+SECTION ANSWER
+cz. 3600 IN NS a.ns.nic.cz.
+cz. 3600 IN NS b.ns.nic.cz.
+cz. 3600 IN NS c.ns.nic.cz.
+cz. 3600 IN NS d.ns.nic.cz.
+cz. 3600 IN RRSIG NS 13 1 3600 20190705184721 20190622030526 6318 cz. SzhZGIFskUTnlxipSleB+IghUpyhS1eV PubDzCU/CC0LmDBoAVwfiY8zKWdPSu0X 5544N2KzZ5JrPoasQkOLzg==
+SECTION ADDITIONAL
+a.ns.nic.cz. 3600 IN A 194.0.12.1
+a.ns.nic.cz. 3600 IN AAAA 2001:678:f::1
+b.ns.nic.cz. 3600 IN A 194.0.13.1
+b.ns.nic.cz. 3600 IN AAAA 2001:678:10::1
+d.ns.nic.cz. 3600 IN A 193.29.206.1
+d.ns.nic.cz. 3600 IN AAAA 2001:678:1::1
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH subdomain
+ADJUST copy_id copy_query
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+cz. IN NS
+SECTION ANSWER
+cz. 3600 IN NS a.ns.nic.cz.
+cz. 3600 IN NS b.ns.nic.cz.
+cz. 3600 IN NS c.ns.nic.cz.
+cz. 3600 IN NS d.ns.nic.cz.
+cz. 3600 IN RRSIG NS 13 1 3600 20190705184721 20190622030526 6318 cz. SzhZGIFskUTnlxipSleB+IghUpyhS1eV PubDzCU/CC0LmDBoAVwfiY8zKWdPSu0X 5544N2KzZ5JrPoasQkOLzg==
+ENTRY_END
+
+
+
+
+RANGE_END
+
+
+
+; Group's zones:
+;	csas.cz.
+; Server names:
+;	ddnsa.csas.cz.
+;	ddnsb.csas.cz.
+;	ddnsc.csas.cz.
+;	ddnsd.csas.cz.
+RANGE_BEGIN 0 1000
+	ADDRESS 194.50.240.64
+	ADDRESS 194.50.240.192
+	ADDRESS 194.50.240.194
+	ADDRESS 194.50.240.66
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+ddnsd.csas.cz. IN NS
+SECTION AUTHORITY
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+csas.cz. 120 IN SOA ddnsa.csas.cz. domainservices.csas.cz. 2019061320 28800 1800 2592000 120
+gfr9qt699hmcloa9radenpk7pqeikiu8.csas.cz. 120 IN NSEC3 1 0 1 31245099125aedf7 gfr9qt699hmcloa9radenpk7pqeikiu9 TXT
+gfr9qt699hmcloa9radenpk7pqeikiu8.csas.cz. 120 IN RRSIG NSEC3 7 3 120 20190702130338 20190625130338 26663 csas.cz. OWtiEsmO7VnUV2MQp3gZJmOAQw4n81DH 9c5FFJW6MBE3afaIqGTvWYCgRipEEvZF qPBVxGpptVsMbuELagewwZYtR+EEh2A/ qMf/wVC//t2c67YFIxMILi9ijleYS5y8 m5Mu+logobk2Resxs0kC47kwNP9KSh7s gm3SFjK1LXRXg19UmiabMIINoOoAE1M0 XePGhiaqhFwros32p++2JrCdaYrPXLWy VuENN0chZ/hE55ic4M7KpxZ12+oPzigk tIeh9sqTaKpGJBZk4vlJQLq2zfL/gnKZ CRRN8bJQ/ZsSZG//rL0nqZcgyxQqXI9w As8TBPtQ9IQWq2K5MxjKHg==
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
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+SECTION AUTHORITY
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+csas.cz. 120 IN SOA ddnsa.csas.cz. domainservices.csas.cz. 2019061320 28800 1800 2592000 120
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
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+SECTION AUTHORITY
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+csas.cz. 120 IN SOA ddnsa.csas.cz. domainservices.csas.cz. 2019061320 28800 1800 2592000 120
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+ddnsd.csas.cz. IN AAAA
+SECTION AUTHORITY
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+csas.cz. 120 IN SOA ddnsa.csas.cz. domainservices.csas.cz. 2019061320 28800 1800 2592000 120
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+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+csas.cz. IN DNSKEY
+SECTION ANSWER
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+csas.cz. 7200 IN RRSIG DNSKEY 7 2 7200 20190630181024 20190623181024 8196 csas.cz. t8HaIHf6FCi91a3ppWC4bAiN+WvZPdbf ESinQ+iYFSWk7NlCw45eT/0SpRWNQ5jQ fvWkkvBDDuHDv9FVdmqkvAuMCf0/GgnM 2bdOQt/q2Hp3E91eFpHW1fx7YtQabj+r 9Ww30ewUplDE2v6JlHnJzm53mYsbUUum l+rAtq+QJnb8sjjn2JceDtQLBkZaLsLe vUuFL/Hz/WvvMgjYUyuxbK4xxJByiymo hZIDxA8TWcaoFFyiP+Rv4leqaxVLXun4 VsWsCE2YYtOqrYRaq2UJvbSIFAPdix5Q EL44TXYlJ00NbngD480tJ8TwyNTm4CLp 8Z85xtmpYfKO3VFAycL0zV/7fOJRkoPQ LrBxClIbeQJlQapm1FMQQK/FFfHKSVRq 659VLfDbxfbTU/yWOmlUldaB8r7y6BhD iq4u/IZqIU5eTIbeoMd3HBerKREo0vOy UPCoW4OJ3Q9/WQ18cPsVW+BKjkKRrV4T VQKc52jwkPufUq8fNuVeuZ+8cvgIaUfD 8Xie+N2Trlh5tfaAAg9etgu0EmoEAP8V 1mTzT54losWySfSh5JNx5fDtUaxZI/q3 2+mbgnO4QlGB9eAhoA6JRHByWf+Gf9rR hEktuZqg2Uw4ifOebJsQE4atFr8Tr910 xihtrgtx/y6HwpB9nIr7V91ewn6lKMEz d4ordmuS+1Q=
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+ddnsa.csas.cz. IN A
+SECTION ANSWER
+ddnsa.csas.cz. 7200 IN A 194.50.240.64
+ddnsa.csas.cz. 7200 IN RRSIG A 7 3 7200 20190630180929 20190623180929 26663 csas.cz. QJCNptf+bgoFFzW6vh6lMnevBqaHq1Qk p7UB7hJZfqewhVJsf4/aZlUJg9Ulq990 xe1K+Vw2H7zFKRmS+BhLL0NVS6F/uo3g VWU7UkiLCUdICMNmBlUfv6dTJmovHydF DeCtS8eunKTYKnvSklmr/aLKnFFEaeoi SUF8hkHM2fADZekxqTEMS2ATjlY0rbTb biDd4c1tZdSDeUV7z4B4pHVdgVFBOi6+ kL4MtMM2AY4o9h31jOUGFnfA0cJPmxNN Cx+qgBAl0zKL9+uFrBqB6nYgmd0a1pRa UEQCcVVKkSjDX3gWHtO/nqflFmyDNV4Y OlVLcHVCDNqRtwIRwucUOg==
+SECTION AUTHORITY
+csas.cz. 7200 IN NS ddnsa.csas.cz.
+csas.cz. 7200 IN NS ddnsb.csas.cz.
+csas.cz. 7200 IN NS ddnsc.csas.cz.
+csas.cz. 7200 IN NS ddnsd.csas.cz.
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+SECTION ADDITIONAL
+ddnsb.csas.cz. 7200 IN A 194.50.240.192
+ddnsb.csas.cz. 7200 IN RRSIG A 7 3 7200 20190630180929 20190623180929 26663 csas.cz. CXelkXBmt3nR60+gTwRcTXTVH1OBpfAE McYGfcEmxk8t+wFwLrCfM+6mJUWbV3a8 cIggoBHU8gJxarnIX4K5bXNel2QRzlTa +qTTPPTxH5LwHayDwoo5edk6c2HkCrY3 qChg5SyjuNxxsF4ybqvqIU0d/kM6wqG7 pKPmplD9BNJmzVIVQ8aTBMhdrvIcqK/f 81TGgNxMqJxfpTYKmnA8vVqpJ3C1kbfn no+ux39NY7Wj58NwI+UIcDlmBj414MSz Z4wEfYSgtVnEA8fO+ufZ3jaxjk6NClz+ XMP1gYj/y08bj0h5ACIKJqci2uqPujoi TNBYzQWn6LVPqNIM8O7eSg==
+ddnsc.csas.cz. 7200 IN A 194.50.240.66
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+ddnsd.csas.cz. 7200 IN A 194.50.240.194
+ddnsd.csas.cz. 7200 IN RRSIG A 7 3 7200 20190630180929 20190623180929 26663 csas.cz. nsWIVa/SusXOatYzHtX8IPkETOBo90yd Zz8ce1PQhUawbQamihm1di90qJSQJ/i4 QCdL5ulxKJdMv8jLBjIBGe1H08d43luD OmLwkiBNoROZ1apKKabSQAmJTuwIxZCD sqYti2+rEbmOaRC1n96fIH2HWL9pYAnn C0GrvoWEDeVkSHI70Ei9CUCpUNOrPzhS BZc3PrB0DhojkzlXj359e4OhO1gH2QDp 2Uj05suhlIEzQf3lsvvIRUOrMPG2i6Fh j3yThN21+kuVyasrsN5Pv6Dp52U1k60l Y7AuwQwMUXrsdrK3/15DyxSS+pHenpsq cBI3Rb8P4Z6uVxZv9sQ4rQ==
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+ddnsb.csas.cz. IN AAAA
+SECTION AUTHORITY
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+csas.cz. 120 IN SOA ddnsa.csas.cz. domainservices.csas.cz. 2019061320 28800 1800 2592000 120
+kl8ko9vcu5os0r0marmli019btprhvdr.csas.cz. 120 IN NSEC3 1 0 1 31245099125aedf7 kl8ko9vcu5os0r0marmli019btprhvds TXT
+kl8ko9vcu5os0r0marmli019btprhvdr.csas.cz. 120 IN RRSIG NSEC3 7 3 120 20190702130338 20190625130338 26663 csas.cz. ebbykapJt+h+uDJlz84Yu4rpx7spx8aY bbR/BCMIVJ6HjziYnwwbBQuyyd6t281+ pdn+2Dxo5tUJ0Kw4oatMPVhID8Psasd3 2Za8bZrouTk8RcQislJCj1jPi2HMIQUI dvJ1aCMC6vn1vI++ZMvcxfptxgmWyL46 i4P3xZAwtrB6hCVrctQ0dbbp1nswh1go YFIf3Hzxu2NHfXZYMdXXb1cLuOZ5L17g UZlqqgcrudLORc2cHj0NcjVT2PscMeoy a/jFNJwCHmkfI3nCAeXmemz/txQUY01u SxBNjkd/y2DVSIgvDPY/Zz0dW4gYdcMG 4T4D43oBTG6w06CgBg1QQw==
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+csas.cz. IN A
+SECTION ANSWER
+csas.cz. 120 IN A 194.50.240.198
+csas.cz. 120 IN A 194.50.240.70
+csas.cz. 120 IN RRSIG A 7 2 120 20190701063211 20190624063211 26663 csas.cz. UXxlRUL6nBVmcrcP4kkryr7lfVxnQHs4 z2WahLZEIaQdf56Iw/+bxddThPD9l3a0 rBCwURI8QMspgPks+7UprWN5TESIifiP W9qJLDuvtD+sVoLgunBAwgi1sE8KfRas asbiISaRpot+3IqJYzYi9X9O5JMdYCuS H9nfayDebVlbC4ChAo5Rcdpkzfb7DwFp gDFKdn+Lmp7IdImSlvJQQT2Mqxpew+gd vMBr5ZN82G8zlsrrHz4n2/kF/SqCYTCG q1WLZUsMvLsP+ha3TAR1t/iG9ayw5Mll 8N2c+AejB2lMwTIlBX+zLlJYT0MoNCyF cMNoCxwjENtDMbq9QZKowA==
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+ddnsc.csas.cz. IN A
+SECTION ANSWER
+ddnsc.csas.cz. 7200 IN A 194.50.240.66
+ddnsc.csas.cz. 7200 IN RRSIG A 7 3 7200 20190630180929 20190623180929 26663 csas.cz. AHQJp3i/UzKmjm/hhmEM1mhV7gPAq2rX 0z4ZOF+ZDyL57nXSHnzGqz4sdd3Q0E1H pmGENdgiOR1Grabo6X3QIp7mZbuAR14T 5TQYHSDoTZ+aTOkqvxCxfUCpEYLVHlbP whE+ntazt0gmkko3eGUBMefMv+JVmuwy tirS7pxlNL1VRnKtbfDsWJ2zmJuur/WK wGzHCMybt4fITB0Og/I9pnwMwykdxhpF bo/MQAa35oTefzvWsD3uFKOhrAc7CP2N MyqDFzv0QDN00s0yFXHHxNg3QFXLAg16 4khZaKT076k+F5N/ufsoIeU/AbByx82T PxpLg8NCh9nNvzgqoCEccw==
+SECTION AUTHORITY
+csas.cz. 7200 IN NS ddnsa.csas.cz.
+csas.cz. 7200 IN NS ddnsb.csas.cz.
+csas.cz. 7200 IN NS ddnsc.csas.cz.
+csas.cz. 7200 IN NS ddnsd.csas.cz.
+csas.cz. 7200 IN RRSIG NS 7 2 7200 20190630180929 20190623180929 26663 csas.cz. PLqM9UHNFbb8GmE+SlzSCjAEKYsklbgt CnWf9G26HkwtacOyJkIHe+T0m94rJZTd 6Mnn32Sw/at6idSvVNGQfE6DIKr2rtK6 lJNe0HPMxYWC9Tr5zpzW1/SjLVooMw6n m8K+18RBI33PBI69UgXyuePnWefdTYOJ g4SK3rR2wUlFxnELEFGfYkytZ6tLi1Cd bTgch93lDnXNBRZ2t/mu5jPyv4NTdKCo WgIMJJcuFdPr/YRVRaemkVEup7qVYImk pa4n+7MMERTL/dw+GxtnZ2YKqyxcepYo rPib3FSTaOFZjEPqNPDNfXXYW+bPmWFP 9ESqUtgmvZ1rMDZbr8lbgQ==
+SECTION ADDITIONAL
+ddnsa.csas.cz. 7200 IN A 194.50.240.64
+ddnsa.csas.cz. 7200 IN RRSIG A 7 3 7200 20190630180929 20190623180929 26663 csas.cz. QJCNptf+bgoFFzW6vh6lMnevBqaHq1Qk p7UB7hJZfqewhVJsf4/aZlUJg9Ulq990 xe1K+Vw2H7zFKRmS+BhLL0NVS6F/uo3g VWU7UkiLCUdICMNmBlUfv6dTJmovHydF DeCtS8eunKTYKnvSklmr/aLKnFFEaeoi SUF8hkHM2fADZekxqTEMS2ATjlY0rbTb biDd4c1tZdSDeUV7z4B4pHVdgVFBOi6+ kL4MtMM2AY4o9h31jOUGFnfA0cJPmxNN Cx+qgBAl0zKL9+uFrBqB6nYgmd0a1pRa UEQCcVVKkSjDX3gWHtO/nqflFmyDNV4Y OlVLcHVCDNqRtwIRwucUOg==
+ddnsb.csas.cz. 7200 IN A 194.50.240.192
+ddnsb.csas.cz. 7200 IN RRSIG A 7 3 7200 20190630180929 20190623180929 26663 csas.cz. CXelkXBmt3nR60+gTwRcTXTVH1OBpfAE McYGfcEmxk8t+wFwLrCfM+6mJUWbV3a8 cIggoBHU8gJxarnIX4K5bXNel2QRzlTa +qTTPPTxH5LwHayDwoo5edk6c2HkCrY3 qChg5SyjuNxxsF4ybqvqIU0d/kM6wqG7 pKPmplD9BNJmzVIVQ8aTBMhdrvIcqK/f 81TGgNxMqJxfpTYKmnA8vVqpJ3C1kbfn no+ux39NY7Wj58NwI+UIcDlmBj414MSz Z4wEfYSgtVnEA8fO+ufZ3jaxjk6NClz+ XMP1gYj/y08bj0h5ACIKJqci2uqPujoi TNBYzQWn6LVPqNIM8O7eSg==
+ddnsd.csas.cz. 7200 IN A 194.50.240.194
+ddnsd.csas.cz. 7200 IN RRSIG A 7 3 7200 20190630180929 20190623180929 26663 csas.cz. nsWIVa/SusXOatYzHtX8IPkETOBo90yd Zz8ce1PQhUawbQamihm1di90qJSQJ/i4 QCdL5ulxKJdMv8jLBjIBGe1H08d43luD OmLwkiBNoROZ1apKKabSQAmJTuwIxZCD sqYti2+rEbmOaRC1n96fIH2HWL9pYAnn C0GrvoWEDeVkSHI70Ei9CUCpUNOrPzhS BZc3PrB0DhojkzlXj359e4OhO1gH2QDp 2Uj05suhlIEzQf3lsvvIRUOrMPG2i6Fh j3yThN21+kuVyasrsN5Pv6Dp52U1k60l Y7AuwQwMUXrsdrK3/15DyxSS+pHenpsq cBI3Rb8P4Z6uVxZv9sQ4rQ==
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NXDOMAIN
+SECTION QUESTION
+csas.cz. IN DS
+SECTION AUTHORITY
+cz. 60 IN SOA cecf53-ant-MS2A-1.csin.cz. hostmaster.cecf53-ant-MS2A-1.csin.cz. 2019061307 10800 3600 604800 60
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+ddnsb.csas.cz. IN NS
+SECTION AUTHORITY
+csas.cz. 120 IN RRSIG SOA 7 2 120 20190630054550 20190623054550 26663 csas.cz. c/sxvp5WLJOsDGgnhxPOk9oBwXRtsUXa enyWg5rd8yBcquHqfFKQu1v8wEPjJjAH B6joG1tJXq99nxtCN4jlDipPKLIzWxba aYIxE8Pab199qiHrR5vxO4KgPxRXbg5d gzIVrrhB+h23DZDacQ+l+kQWSAcycjPh xFvNjAZrH4obU/F+jHt4ix5XqEVuDrPQ YTGBGEUpl7YbcyaROzVP3dtCQZamkfaB CQYoNAJlNw6YFG1qulPm3pn3jJHhu88f dFgCisWfp7TjMYn7Id7aYJtliagE47xu ASnhOtaeXAVxDGUIkOI5u8uUCC/jAiHr MgARE5rcqh2AIZeSv0BiMQ==
+csas.cz. 120 IN SOA ddnsa.csas.cz. domainservices.csas.cz. 2019061320 28800 1800 2592000 120
+kl8ko9vcu5os0r0marmli019btprhvdr.csas.cz. 120 IN NSEC3 1 0 1 31245099125aedf7 kl8ko9vcu5os0r0marmli019btprhvds TXT
+kl8ko9vcu5os0r0marmli019btprhvdr.csas.cz. 120 IN RRSIG NSEC3 7 3 120 20190702130338 20190625130338 26663 csas.cz. ebbykapJt+h+uDJlz84Yu4rpx7spx8aY bbR/BCMIVJ6HjziYnwwbBQuyyd6t281+ pdn+2Dxo5tUJ0Kw4oatMPVhID8Psasd3 2Za8bZrouTk8RcQislJCj1jPi2HMIQUI dvJ1aCMC6vn1vI++ZMvcxfptxgmWyL46 i4P3xZAwtrB6hCVrctQ0dbbp1nswh1go YFIf3Hzxu2NHfXZYMdXXb1cLuOZ5L17g UZlqqgcrudLORc2cHj0NcjVT2PscMeoy a/jFNJwCHmkfI3nCAeXmemz/txQUY01u SxBNjkd/y2DVSIgvDPY/Zz0dW4gYdcMG 4T4D43oBTG6w06CgBg1QQw==
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+ddnsb.csas.cz. IN A
+SECTION ANSWER
+ddnsb.csas.cz. 7200 IN A 194.50.240.192
+ddnsb.csas.cz. 7200 IN RRSIG A 7 3 7200 20190630180929 20190623180929 26663 csas.cz. CXelkXBmt3nR60+gTwRcTXTVH1OBpfAE McYGfcEmxk8t+wFwLrCfM+6mJUWbV3a8 cIggoBHU8gJxarnIX4K5bXNel2QRzlTa +qTTPPTxH5LwHayDwoo5edk6c2HkCrY3 qChg5SyjuNxxsF4ybqvqIU0d/kM6wqG7 pKPmplD9BNJmzVIVQ8aTBMhdrvIcqK/f 81TGgNxMqJxfpTYKmnA8vVqpJ3C1kbfn no+ux39NY7Wj58NwI+UIcDlmBj414MSz Z4wEfYSgtVnEA8fO+ufZ3jaxjk6NClz+ XMP1gYj/y08bj0h5ACIKJqci2uqPujoi TNBYzQWn6LVPqNIM8O7eSg==
+SECTION AUTHORITY
+csas.cz. 7200 IN NS ddnsa.csas.cz.
+csas.cz. 7200 IN NS ddnsb.csas.cz.
+csas.cz. 7200 IN NS ddnsc.csas.cz.
+csas.cz. 7200 IN NS ddnsd.csas.cz.
+csas.cz. 7200 IN RRSIG NS 7 2 7200 20190630180929 20190623180929 26663 csas.cz. PLqM9UHNFbb8GmE+SlzSCjAEKYsklbgt CnWf9G26HkwtacOyJkIHe+T0m94rJZTd 6Mnn32Sw/at6idSvVNGQfE6DIKr2rtK6 lJNe0HPMxYWC9Tr5zpzW1/SjLVooMw6n m8K+18RBI33PBI69UgXyuePnWefdTYOJ g4SK3rR2wUlFxnELEFGfYkytZ6tLi1Cd bTgch93lDnXNBRZ2t/mu5jPyv4NTdKCo WgIMJJcuFdPr/YRVRaemkVEup7qVYImk pa4n+7MMERTL/dw+GxtnZ2YKqyxcepYo rPib3FSTaOFZjEPqNPDNfXXYW+bPmWFP 9ESqUtgmvZ1rMDZbr8lbgQ==
+SECTION ADDITIONAL
+ddnsa.csas.cz. 7200 IN A 194.50.240.64
+ddnsa.csas.cz. 7200 IN RRSIG A 7 3 7200 20190630180929 20190623180929 26663 csas.cz. QJCNptf+bgoFFzW6vh6lMnevBqaHq1Qk p7UB7hJZfqewhVJsf4/aZlUJg9Ulq990 xe1K+Vw2H7zFKRmS+BhLL0NVS6F/uo3g VWU7UkiLCUdICMNmBlUfv6dTJmovHydF DeCtS8eunKTYKnvSklmr/aLKnFFEaeoi SUF8hkHM2fADZekxqTEMS2ATjlY0rbTb biDd4c1tZdSDeUV7z4B4pHVdgVFBOi6+ kL4MtMM2AY4o9h31jOUGFnfA0cJPmxNN Cx+qgBAl0zKL9+uFrBqB6nYgmd0a1pRa UEQCcVVKkSjDX3gWHtO/nqflFmyDNV4Y OlVLcHVCDNqRtwIRwucUOg==
+ddnsc.csas.cz. 7200 IN A 194.50.240.66
+ddnsc.csas.cz. 7200 IN RRSIG A 7 3 7200 20190630180929 20190623180929 26663 csas.cz. AHQJp3i/UzKmjm/hhmEM1mhV7gPAq2rX 0z4ZOF+ZDyL57nXSHnzGqz4sdd3Q0E1H pmGENdgiOR1Grabo6X3QIp7mZbuAR14T 5TQYHSDoTZ+aTOkqvxCxfUCpEYLVHlbP whE+ntazt0gmkko3eGUBMefMv+JVmuwy tirS7pxlNL1VRnKtbfDsWJ2zmJuur/WK wGzHCMybt4fITB0Og/I9pnwMwykdxhpF bo/MQAa35oTefzvWsD3uFKOhrAc7CP2N MyqDFzv0QDN00s0yFXHHxNg3QFXLAg16 4khZaKT076k+F5N/ufsoIeU/AbByx82T PxpLg8NCh9nNvzgqoCEccw==
+ddnsd.csas.cz. 7200 IN A 194.50.240.194
+ddnsd.csas.cz. 7200 IN RRSIG A 7 3 7200 20190630180929 20190623180929 26663 csas.cz. nsWIVa/SusXOatYzHtX8IPkETOBo90yd Zz8ce1PQhUawbQamihm1di90qJSQJ/i4 QCdL5ulxKJdMv8jLBjIBGe1H08d43luD OmLwkiBNoROZ1apKKabSQAmJTuwIxZCD sqYti2+rEbmOaRC1n96fIH2HWL9pYAnn C0GrvoWEDeVkSHI70Ei9CUCpUNOrPzhS BZc3PrB0DhojkzlXj359e4OhO1gH2QDp 2Uj05suhlIEzQf3lsvvIRUOrMPG2i6Fh j3yThN21+kuVyasrsN5Pv6Dp52U1k60l Y7AuwQwMUXrsdrK3/15DyxSS+pHenpsq cBI3Rb8P4Z6uVxZv9sQ4rQ==
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+ddnsd.csas.cz. IN A
+SECTION ANSWER
+ddnsd.csas.cz. 7200 IN A 194.50.240.194
+ddnsd.csas.cz. 7200 IN RRSIG A 7 3 7200 20190630180929 20190623180929 26663 csas.cz. nsWIVa/SusXOatYzHtX8IPkETOBo90yd Zz8ce1PQhUawbQamihm1di90qJSQJ/i4 QCdL5ulxKJdMv8jLBjIBGe1H08d43luD OmLwkiBNoROZ1apKKabSQAmJTuwIxZCD sqYti2+rEbmOaRC1n96fIH2HWL9pYAnn C0GrvoWEDeVkSHI70Ei9CUCpUNOrPzhS BZc3PrB0DhojkzlXj359e4OhO1gH2QDp 2Uj05suhlIEzQf3lsvvIRUOrMPG2i6Fh j3yThN21+kuVyasrsN5Pv6Dp52U1k60l Y7AuwQwMUXrsdrK3/15DyxSS+pHenpsq cBI3Rb8P4Z6uVxZv9sQ4rQ==
+SECTION AUTHORITY
+csas.cz. 7200 IN NS ddnsa.csas.cz.
+csas.cz. 7200 IN NS ddnsb.csas.cz.
+csas.cz. 7200 IN NS ddnsc.csas.cz.
+csas.cz. 7200 IN NS ddnsd.csas.cz.
+csas.cz. 7200 IN RRSIG NS 7 2 7200 20190630180929 20190623180929 26663 csas.cz. PLqM9UHNFbb8GmE+SlzSCjAEKYsklbgt CnWf9G26HkwtacOyJkIHe+T0m94rJZTd 6Mnn32Sw/at6idSvVNGQfE6DIKr2rtK6 lJNe0HPMxYWC9Tr5zpzW1/SjLVooMw6n m8K+18RBI33PBI69UgXyuePnWefdTYOJ g4SK3rR2wUlFxnELEFGfYkytZ6tLi1Cd bTgch93lDnXNBRZ2t/mu5jPyv4NTdKCo WgIMJJcuFdPr/YRVRaemkVEup7qVYImk pa4n+7MMERTL/dw+GxtnZ2YKqyxcepYo rPib3FSTaOFZjEPqNPDNfXXYW+bPmWFP 9ESqUtgmvZ1rMDZbr8lbgQ==
+SECTION ADDITIONAL
+ddnsa.csas.cz. 7200 IN A 194.50.240.64
+ddnsa.csas.cz. 7200 IN RRSIG A 7 3 7200 20190630180929 20190623180929 26663 csas.cz. QJCNptf+bgoFFzW6vh6lMnevBqaHq1Qk p7UB7hJZfqewhVJsf4/aZlUJg9Ulq990 xe1K+Vw2H7zFKRmS+BhLL0NVS6F/uo3g VWU7UkiLCUdICMNmBlUfv6dTJmovHydF DeCtS8eunKTYKnvSklmr/aLKnFFEaeoi SUF8hkHM2fADZekxqTEMS2ATjlY0rbTb biDd4c1tZdSDeUV7z4B4pHVdgVFBOi6+ kL4MtMM2AY4o9h31jOUGFnfA0cJPmxNN Cx+qgBAl0zKL9+uFrBqB6nYgmd0a1pRa UEQCcVVKkSjDX3gWHtO/nqflFmyDNV4Y OlVLcHVCDNqRtwIRwucUOg==
+ddnsb.csas.cz. 7200 IN A 194.50.240.192
+ddnsb.csas.cz. 7200 IN RRSIG A 7 3 7200 20190630180929 20190623180929 26663 csas.cz. CXelkXBmt3nR60+gTwRcTXTVH1OBpfAE McYGfcEmxk8t+wFwLrCfM+6mJUWbV3a8 cIggoBHU8gJxarnIX4K5bXNel2QRzlTa +qTTPPTxH5LwHayDwoo5edk6c2HkCrY3 qChg5SyjuNxxsF4ybqvqIU0d/kM6wqG7 pKPmplD9BNJmzVIVQ8aTBMhdrvIcqK/f 81TGgNxMqJxfpTYKmnA8vVqpJ3C1kbfn no+ux39NY7Wj58NwI+UIcDlmBj414MSz Z4wEfYSgtVnEA8fO+ufZ3jaxjk6NClz+ XMP1gYj/y08bj0h5ACIKJqci2uqPujoi TNBYzQWn6LVPqNIM8O7eSg==
+ddnsc.csas.cz. 7200 IN A 194.50.240.66
+ddnsc.csas.cz. 7200 IN RRSIG A 7 3 7200 20190630180929 20190623180929 26663 csas.cz. AHQJp3i/UzKmjm/hhmEM1mhV7gPAq2rX 0z4ZOF+ZDyL57nXSHnzGqz4sdd3Q0E1H pmGENdgiOR1Grabo6X3QIp7mZbuAR14T 5TQYHSDoTZ+aTOkqvxCxfUCpEYLVHlbP whE+ntazt0gmkko3eGUBMefMv+JVmuwy tirS7pxlNL1VRnKtbfDsWJ2zmJuur/WK wGzHCMybt4fITB0Og/I9pnwMwykdxhpF bo/MQAa35oTefzvWsD3uFKOhrAc7CP2N MyqDFzv0QDN00s0yFXHHxNg3QFXLAg16 4khZaKT076k+F5N/ufsoIeU/AbByx82T PxpLg8NCh9nNvzgqoCEccw==
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+ddnsa.csas.cz. IN AAAA
+SECTION AUTHORITY
+csas.cz. 120 IN RRSIG SOA 7 2 120 20190630054550 20190623054550 26663 csas.cz. c/sxvp5WLJOsDGgnhxPOk9oBwXRtsUXa enyWg5rd8yBcquHqfFKQu1v8wEPjJjAH B6joG1tJXq99nxtCN4jlDipPKLIzWxba aYIxE8Pab199qiHrR5vxO4KgPxRXbg5d gzIVrrhB+h23DZDacQ+l+kQWSAcycjPh xFvNjAZrH4obU/F+jHt4ix5XqEVuDrPQ YTGBGEUpl7YbcyaROzVP3dtCQZamkfaB CQYoNAJlNw6YFG1qulPm3pn3jJHhu88f dFgCisWfp7TjMYn7Id7aYJtliagE47xu ASnhOtaeXAVxDGUIkOI5u8uUCC/jAiHr MgARE5rcqh2AIZeSv0BiMQ==
+csas.cz. 120 IN SOA ddnsa.csas.cz. domainservices.csas.cz. 2019061320 28800 1800 2592000 120
+j0hp68elhot3j046r6mr0tnqlns1dbc7.csas.cz. 120 IN NSEC3 1 0 1 31245099125aedf7 j0hp68elhot3j046r6mr0tnqlns1dbc8 TXT
+j0hp68elhot3j046r6mr0tnqlns1dbc7.csas.cz. 120 IN RRSIG NSEC3 7 3 120 20190702130338 20190625130338 26663 csas.cz. gUyltGyzdD2L6M29xgqWXMO834aavtFc Si2oAbET0rEJZ5w9ewhEJdVT65MMUUlK wvVX239N7PtsyL+fQvxu5TZ8du0ML8Oi KBp3gao/stajg/lZFd6zVvDWliC3+psL 7PFmD5au5qcrYc6HLc8m8D4hHFPREyd6 1tLGA98RevbQGfrDYODXi6G28vwbxoYU POn4mo82MnVVTZhh58cu7nKRRvKAtay6 VZVWZBOuxy8u+LNsrj3vpDbaOIiWzHd0 pRACsv3LqGpxQNH8avSalWLBvLWchAHj 0T2M+doO8UVaCsyFo/3wF2TXdgFcOAr3 xDIdhHCCoanRVFZ+gFAwIw==
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+ddnsa.csas.cz. IN NS
+SECTION AUTHORITY
+csas.cz. 120 IN RRSIG SOA 7 2 120 20190630054550 20190623054550 26663 csas.cz. c/sxvp5WLJOsDGgnhxPOk9oBwXRtsUXa enyWg5rd8yBcquHqfFKQu1v8wEPjJjAH B6joG1tJXq99nxtCN4jlDipPKLIzWxba aYIxE8Pab199qiHrR5vxO4KgPxRXbg5d gzIVrrhB+h23DZDacQ+l+kQWSAcycjPh xFvNjAZrH4obU/F+jHt4ix5XqEVuDrPQ YTGBGEUpl7YbcyaROzVP3dtCQZamkfaB CQYoNAJlNw6YFG1qulPm3pn3jJHhu88f dFgCisWfp7TjMYn7Id7aYJtliagE47xu ASnhOtaeXAVxDGUIkOI5u8uUCC/jAiHr MgARE5rcqh2AIZeSv0BiMQ==
+csas.cz. 120 IN SOA ddnsa.csas.cz. domainservices.csas.cz. 2019061320 28800 1800 2592000 120
+j0hp68elhot3j046r6mr0tnqlns1dbc7.csas.cz. 120 IN NSEC3 1 0 1 31245099125aedf7 j0hp68elhot3j046r6mr0tnqlns1dbc8 TXT
+j0hp68elhot3j046r6mr0tnqlns1dbc7.csas.cz. 120 IN RRSIG NSEC3 7 3 120 20190702130338 20190625130338 26663 csas.cz. gUyltGyzdD2L6M29xgqWXMO834aavtFc Si2oAbET0rEJZ5w9ewhEJdVT65MMUUlK wvVX239N7PtsyL+fQvxu5TZ8du0ML8Oi KBp3gao/stajg/lZFd6zVvDWliC3+psL 7PFmD5au5qcrYc6HLc8m8D4hHFPREyd6 1tLGA98RevbQGfrDYODXi6G28vwbxoYU POn4mo82MnVVTZhh58cu7nKRRvKAtay6 VZVWZBOuxy8u+LNsrj3vpDbaOIiWzHd0 pRACsv3LqGpxQNH8avSalWLBvLWchAHj 0T2M+doO8UVaCsyFo/3wF2TXdgFcOAr3 xDIdhHCCoanRVFZ+gFAwIw==
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+ddnsc.csas.cz. IN AAAA
+SECTION AUTHORITY
+c1c03am0n36kncp4iqb4buoqo1ectql4.csas.cz. 120 IN NSEC3 1 0 1 31245099125aedf7 c1c03am0n36kncp4iqb4buoqo1ectql5 TXT
+c1c03am0n36kncp4iqb4buoqo1ectql4.csas.cz. 120 IN RRSIG NSEC3 7 3 120 20190702130338 20190625130338 26663 csas.cz. FKjWbcw5aP2HzHFy2t+M462dxM1ph0FW 02Tohh/aJQOp1iKQOi6u1V2tI3H9CMXW xeIAktZ+xiUDRYLX50fNuJZMaSsn7r5A LYjVAKGzwMPncIf6IlEDYkj1I1rdp6z8 LvWsWNO1wfIPq1Dw2geN60bcz3D7r/sY WfjU/7jO9f0nekZZXI2qFsMSYd9Dkaq7 mlpP0NrWnUbCjL+BfuLFNebh8g3D8f5w Tq3R9czwW5YTVXUquBIrjiZ0Ko9INgQ/ 4pvJqJ1bsTpmzdODfAssEtpu+es4wLwt ZTe8Ll9VeDB20RqEnAyHZwQRXXVF2t+F vdJU7Desbpu6rElA7IXwRw==
+csas.cz. 120 IN RRSIG SOA 7 2 120 20190630054550 20190623054550 26663 csas.cz. c/sxvp5WLJOsDGgnhxPOk9oBwXRtsUXa enyWg5rd8yBcquHqfFKQu1v8wEPjJjAH B6joG1tJXq99nxtCN4jlDipPKLIzWxba aYIxE8Pab199qiHrR5vxO4KgPxRXbg5d gzIVrrhB+h23DZDacQ+l+kQWSAcycjPh xFvNjAZrH4obU/F+jHt4ix5XqEVuDrPQ YTGBGEUpl7YbcyaROzVP3dtCQZamkfaB CQYoNAJlNw6YFG1qulPm3pn3jJHhu88f dFgCisWfp7TjMYn7Id7aYJtliagE47xu ASnhOtaeXAVxDGUIkOI5u8uUCC/jAiHr MgARE5rcqh2AIZeSv0BiMQ==
+csas.cz. 120 IN SOA ddnsa.csas.cz. domainservices.csas.cz. 2019061320 28800 1800 2592000 120
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH subdomain
+ADJUST copy_id copy_query
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+csas.cz. IN NS
+SECTION ANSWER
+csas.cz. 7200 IN NS ddnsa.csas.cz.
+csas.cz. 7200 IN NS ddnsb.csas.cz.
+csas.cz. 7200 IN NS ddnsc.csas.cz.
+csas.cz. 7200 IN NS ddnsd.csas.cz.
+csas.cz. 7200 IN RRSIG NS 7 2 7200 20190630180929 20190623180929 26663 csas.cz. PLqM9UHNFbb8GmE+SlzSCjAEKYsklbgt CnWf9G26HkwtacOyJkIHe+T0m94rJZTd 6Mnn32Sw/at6idSvVNGQfE6DIKr2rtK6 lJNe0HPMxYWC9Tr5zpzW1/SjLVooMw6n m8K+18RBI33PBI69UgXyuePnWefdTYOJ g4SK3rR2wUlFxnELEFGfYkytZ6tLi1Cd bTgch93lDnXNBRZ2t/mu5jPyv4NTdKCo WgIMJJcuFdPr/YRVRaemkVEup7qVYImk pa4n+7MMERTL/dw+GxtnZ2YKqyxcepYo rPib3FSTaOFZjEPqNPDNfXXYW+bPmWFP 9ESqUtgmvZ1rMDZbr8lbgQ==
+SECTION ADDITIONAL
+ddnsa.csas.cz. 7200 IN A 194.50.240.64
+ddnsa.csas.cz. 7200 IN RRSIG A 7 3 7200 20190630180929 20190623180929 26663 csas.cz. QJCNptf+bgoFFzW6vh6lMnevBqaHq1Qk p7UB7hJZfqewhVJsf4/aZlUJg9Ulq990 xe1K+Vw2H7zFKRmS+BhLL0NVS6F/uo3g VWU7UkiLCUdICMNmBlUfv6dTJmovHydF DeCtS8eunKTYKnvSklmr/aLKnFFEaeoi SUF8hkHM2fADZekxqTEMS2ATjlY0rbTb biDd4c1tZdSDeUV7z4B4pHVdgVFBOi6+ kL4MtMM2AY4o9h31jOUGFnfA0cJPmxNN Cx+qgBAl0zKL9+uFrBqB6nYgmd0a1pRa UEQCcVVKkSjDX3gWHtO/nqflFmyDNV4Y OlVLcHVCDNqRtwIRwucUOg==
+ddnsb.csas.cz. 7200 IN A 194.50.240.192
+ddnsb.csas.cz. 7200 IN RRSIG A 7 3 7200 20190630180929 20190623180929 26663 csas.cz. CXelkXBmt3nR60+gTwRcTXTVH1OBpfAE McYGfcEmxk8t+wFwLrCfM+6mJUWbV3a8 cIggoBHU8gJxarnIX4K5bXNel2QRzlTa +qTTPPTxH5LwHayDwoo5edk6c2HkCrY3 qChg5SyjuNxxsF4ybqvqIU0d/kM6wqG7 pKPmplD9BNJmzVIVQ8aTBMhdrvIcqK/f 81TGgNxMqJxfpTYKmnA8vVqpJ3C1kbfn no+ux39NY7Wj58NwI+UIcDlmBj414MSz Z4wEfYSgtVnEA8fO+ufZ3jaxjk6NClz+ XMP1gYj/y08bj0h5ACIKJqci2uqPujoi TNBYzQWn6LVPqNIM8O7eSg==
+ddnsc.csas.cz. 7200 IN A 194.50.240.66
+ddnsc.csas.cz. 7200 IN RRSIG A 7 3 7200 20190630180929 20190623180929 26663 csas.cz. AHQJp3i/UzKmjm/hhmEM1mhV7gPAq2rX 0z4ZOF+ZDyL57nXSHnzGqz4sdd3Q0E1H pmGENdgiOR1Grabo6X3QIp7mZbuAR14T 5TQYHSDoTZ+aTOkqvxCxfUCpEYLVHlbP whE+ntazt0gmkko3eGUBMefMv+JVmuwy tirS7pxlNL1VRnKtbfDsWJ2zmJuur/WK wGzHCMybt4fITB0Og/I9pnwMwykdxhpF bo/MQAa35oTefzvWsD3uFKOhrAc7CP2N MyqDFzv0QDN00s0yFXHHxNg3QFXLAg16 4khZaKT076k+F5N/ufsoIeU/AbByx82T PxpLg8NCh9nNvzgqoCEccw==
+ddnsd.csas.cz. 7200 IN A 194.50.240.194
+ddnsd.csas.cz. 7200 IN RRSIG A 7 3 7200 20190630180929 20190623180929 26663 csas.cz. nsWIVa/SusXOatYzHtX8IPkETOBo90yd Zz8ce1PQhUawbQamihm1di90qJSQJ/i4 QCdL5ulxKJdMv8jLBjIBGe1H08d43luD OmLwkiBNoROZ1apKKabSQAmJTuwIxZCD sqYti2+rEbmOaRC1n96fIH2HWL9pYAnn C0GrvoWEDeVkSHI70Ei9CUCpUNOrPzhS BZc3PrB0DhojkzlXj359e4OhO1gH2QDp 2Uj05suhlIEzQf3lsvvIRUOrMPG2i6Fh j3yThN21+kuVyasrsN5Pv6Dp52U1k60l Y7AuwQwMUXrsdrK3/15DyxSS+pHenpsq cBI3Rb8P4Z6uVxZv9sQ4rQ==
+ENTRY_END
+
+
+
+
+RANGE_END
+
+
+
+; Group's zones:
+;	com.
+;	net.
+; Server names:
+;	a.gtld-servers.net.
+;	j.gtld-servers.net.
+;	e.gtld-servers.net.
+;	i.gtld-servers.net.
+;	d.gtld-servers.net.
+;	m.gtld-servers.net.
+;	h.gtld-servers.net.
+;	c.gtld-servers.net.
+;	l.gtld-servers.net.
+;	g.gtld-servers.net.
+;	b.gtld-servers.net.
+;	k.gtld-servers.net.
+;	f.gtld-servers.net.
+RANGE_BEGIN 0 1000
+	ADDRESS 2001:502:8cc::30
+	ADDRESS 2001:503:eea3::30
+	ADDRESS 192.5.6.30
+	ADDRESS 192.33.14.30
+	ADDRESS 192.43.172.30
+	ADDRESS 192.12.94.30
+	ADDRESS 192.48.79.30
+	ADDRESS 2001:502:1ca1::30
+	ADDRESS 192.54.112.30
+	ADDRESS 2001:500:856e::30
+	ADDRESS 2001:503:a83e::2:30
+	ADDRESS 192.52.178.30
+	ADDRESS 2001:503:d2d::30
+	ADDRESS 192.26.92.30
+	ADDRESS 192.41.162.30
+	ADDRESS 192.31.80.30
+	ADDRESS 2001:503:83eb::30
+	ADDRESS 192.42.93.30
+	ADDRESS 2001:503:39c1::30
+	ADDRESS 2001:503:231d::2:30
+	ADDRESS 192.35.51.30
+	ADDRESS 2001:500:d937::30
+	ADDRESS 2001:503:d414::30
+	ADDRESS 2001:502:7094::30
+	ADDRESS 2001:501:b1f9::30
+	ADDRESS 192.55.83.30
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+nstld.com. IN DS
+SECTION AUTHORITY
+5V12UURISSGGLPAS52GE1V3R0V7KR5BS.com. 86400 IN NSEC3 1 1 0 - 5v13q049b9ittui4fbdtm34dtev47bgj NS DS RRSIG
+5V12UURISSGGLPAS52GE1V3R0V7KR5BS.com. 86400 IN RRSIG NSEC3 8 2 86400 20190630044250 20190623033250 3800 com. NlBOkX84YgGooJJ2vp+Z/O16Vkz6z1gC Jy1Va3fJyEXfZr/GIm8J3KJ6Eq+xxp1A x3ZWxwUjNH3TGUEme7pDrmusqRpx/TZF Za3dVAYIvsaVgIWtDCn4BLBPrg0HXcon HE60KLgWGQmezzFKrNsy5Tzz9TajUSgQ uOTQHB7TFDg=
+CK0POJMG874LJREF7EFN8430QVIT8BSM.com. 86400 IN NSEC3 1 1 0 - ck0q1gin43n1arrc9osm6qpqr81h5m9a NS SOA RRSIG DNSKEY NSEC3PARAM
+CK0POJMG874LJREF7EFN8430QVIT8BSM.com. 86400 IN RRSIG NSEC3 8 2 86400 20190702044530 20190625033530 3800 com. BMWhk6USUrb7TNJ3dSObn8QEPWvpzedW kP9i4RRPz7V9c2yVPmHSPt29QKsHOYTg iF4uyHt+K8RK8DBIziB19nrOjbb8iRDY 7m5koEj/OrS2peMuF6rqRRmkI6SY/ACy XHb/hRGE4tZd2gThNb7evZkk02IVuhEo njO3NBjCrsw=
+com. 900 IN RRSIG SOA 8 1 900 20190702140912 20190625125912 3800 com. c6kEiaL24fAOXZf4AexmGfQejNxB+Na5 Omftkar0u1SFkd7I03ieGTsJt/aiFVND ucQklNtxUqTC4SQpGLmNYlzIDRvb2vYC GL7tSomPB/Tt4xYczPvNIOJKQOtFAjoL hJn5hj1jCo56iBD5OmbLwQcq8XI/W7xs yvTMfjKpeEQ=
+com. 900 IN SOA a.gtld-servers.net. nstld.verisign-grs.com. 1561471752 1800 900 604800 86400
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+root-servers.net. IN DS
+SECTION AUTHORITY
+A1RT98BS5QGC9NFI51S9HCI47ULJG6JH.net. 86400 IN NSEC3 1 1 0 - a1ruuffjkct2q54p78f8ejgj8jbk7i8b NS SOA RRSIG DNSKEY NSEC3PARAM
+A1RT98BS5QGC9NFI51S9HCI47ULJG6JH.net. 86400 IN RRSIG NSEC3 8 2 86400 20190702055539 20190625044539 2129 net. KgEWjLXuYdPBhlNh2epfnKU879hg4GGf F4m4Fo7ZW+S3uhNqq8pF7sMJCvSs8ZZA Ctcm88XThCeIAxDxLZ5moOlMIWaweVX3 7B7s3mw+3K0cnkYF6J4FqBO8o7x6J3i2 c6kxI3q0DKub23GcXpWZu3x2yIkWuN0I ZgceikGAPpM=
+T2UF21DR03E0BNPB42UQMVUF38P2TA8D.net. 86400 IN NSEC3 1 1 0 - t2ukct9k5i0uhv7b3m3na6jaigdjm0gr NS DS RRSIG
+T2UF21DR03E0BNPB42UQMVUF38P2TA8D.net. 86400 IN RRSIG NSEC3 8 2 86400 20190630054523 20190623043523 2129 net. adpeQf+K6Hr5amhmF9DNK56LVWWnfGHK Dz9t9e7swG/P+4clc4yMKmUvK0OF9aTA kBzDwnzeB+FT+nsg1cWdibs4559AKQCL RtNErPhZRMojUFo6TLM9lQoXhv9i5rZB AJGmirHgSwiAvaUK7tgxX3nr1Atahyew iwHDQIVPhw4=
+net. 900 IN RRSIG SOA 8 1 900 20190702140916 20190625125916 2129 net. cMaAZOeBq2v9urE/L5RZEBRSTmY4/MMJ ADm+GUhaqP3FQ0RD3fO6IU7qdP3jCmlZ QmCl68ZVaMyZvVIcNcv7fokWbqTm9r4j 2NB0W9j/B/ZIOzCV4myDqaylU62tNTUA okGZMzclPCSd2n8ZDHZ3RysudhiZ/8WG FVdsHHtp67c=
+net. 900 IN SOA a.gtld-servers.net. nstld.verisign-grs.com. 1561471756 1800 900 604800 86400
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+net. IN DS
+SECTION AUTHORITY
+A1RT98BS5QGC9NFI51S9HCI47ULJG6JH.net. 86400 IN NSEC3 1 1 0 - a1ruuffjkct2q54p78f8ejgj8jbk7i8b NS SOA RRSIG DNSKEY NSEC3PARAM
+A1RT98BS5QGC9NFI51S9HCI47ULJG6JH.net. 86400 IN RRSIG NSEC3 8 2 86400 20190702055539 20190625044539 2129 net. KgEWjLXuYdPBhlNh2epfnKU879hg4GGf F4m4Fo7ZW+S3uhNqq8pF7sMJCvSs8ZZA Ctcm88XThCeIAxDxLZ5moOlMIWaweVX3 7B7s3mw+3K0cnkYF6J4FqBO8o7x6J3i2 c6kxI3q0DKub23GcXpWZu3x2yIkWuN0I ZgceikGAPpM=
+net. 900 IN RRSIG SOA 8 1 900 20190702140916 20190625125916 2129 net. cMaAZOeBq2v9urE/L5RZEBRSTmY4/MMJ ADm+GUhaqP3FQ0RD3fO6IU7qdP3jCmlZ QmCl68ZVaMyZvVIcNcv7fokWbqTm9r4j 2NB0W9j/B/ZIOzCV4myDqaylU62tNTUA okGZMzclPCSd2n8ZDHZ3RysudhiZ/8WG FVdsHHtp67c=
+net. 900 IN SOA a.gtld-servers.net. nstld.verisign-grs.com. 1561471756 1800 900 604800 86400
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+com. IN DS
+SECTION AUTHORITY
+CK0POJMG874LJREF7EFN8430QVIT8BSM.com. 86400 IN NSEC3 1 1 0 - ck0q1gin43n1arrc9osm6qpqr81h5m9a NS SOA RRSIG DNSKEY NSEC3PARAM
+CK0POJMG874LJREF7EFN8430QVIT8BSM.com. 86400 IN RRSIG NSEC3 8 2 86400 20190702044530 20190625033530 3800 com. BMWhk6USUrb7TNJ3dSObn8QEPWvpzedW kP9i4RRPz7V9c2yVPmHSPt29QKsHOYTg iF4uyHt+K8RK8DBIziB19nrOjbb8iRDY 7m5koEj/OrS2peMuF6rqRRmkI6SY/ACy XHb/hRGE4tZd2gThNb7evZkk02IVuhEo njO3NBjCrsw=
+com. 900 IN RRSIG SOA 8 1 900 20190702140912 20190625125912 3800 com. c6kEiaL24fAOXZf4AexmGfQejNxB+Na5 Omftkar0u1SFkd7I03ieGTsJt/aiFVND ucQklNtxUqTC4SQpGLmNYlzIDRvb2vYC GL7tSomPB/Tt4xYczPvNIOJKQOtFAjoL hJn5hj1jCo56iBD5OmbLwQcq8XI/W7xs yvTMfjKpeEQ=
+com. 900 IN SOA a.gtld-servers.net. nstld.verisign-grs.com. 1561471752 1800 900 604800 86400
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+net. IN DNSKEY
+SECTION ANSWER
+net. 86400 IN DNSKEY 256 3 8 AQPB6mADOfWU6hTegl+pTl1wtjTll+Zn WIuRb8+cU9XNWNPpc3mX+rUqPeiw0RpK kD4QkTqTefWjMqjXMvYn2TxX4V4FMQXY MJr0bgiZXGosA9C9Aa7RgYyt4GJCToXq lM+mTqBjXDkh7yBa8I2X3p6Tt/PoKhiq CtmNl6sggTanJw==
+net. 86400 IN DNSKEY 257 3 8 AQOYBnzqWXIEj6mlgXg4LWC0HP2n8eK8 XqgHlmJ/69iuIHsa1TrHDG6TcOra/pye GKwH0nKZhTmXSuUFGh9BCNiwVDuyyb6O BGy2Nte9Kr8NwWg4q+zhSoOf4D+gC9dE zg0yFdwT0DKEvmNPt0K4jbQDS4Yimb+u PKuF6yieWWrPYYCrv8C9KC8JMze2uT6N uWBfsl2fDUoV4l65qMww06D7n+p7Rbdw WkAZ0fA63mXVXBZF6kpDtsYD7SUB9jhh fLQE/r85bvg3FaSs5Wi2BaqN06SzGWI1 DHu7axthIOeHwg00zxlhTpoYCH0ldoQz +S65zWYi/fRJiyLSBb6JZOvn
+net. 86400 IN RRSIG DNSKEY 8 1 86400 20190704153857 20190619153357 35886 net. T0Dcg9EVsoYzu+hywAW4mW11X/+oW/zt 0tQ8TdsKgY/5+/RL0tZCoU1EqbkBfM5h PxZgupQ0SQ//haveGagTgXOAOpa2nmUa o26dJC0xyZRTHuViy5708DONc88JZt+U pAgFcmJYjTXLu2QNywtyCXhcjnCuYAVG lTrarCn0rzW7PZp94xyGTCegkK9TysCt aqnIS0z/LVA2PjF+5etoEl7nWxCa1iUY 7as3zQ8CYlSDLwf7Sx4pUA/4hLZftwdO gNvb/pUdy7Zy/+6SGS3K4CPFkWG9kfs/ /76iMG6GkV2loGJApIFtYlui5iFaNfIM YBTD29dqC2I9ofe4WJnmpg==
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+com. IN DNSKEY
+SECTION ANSWER
+com. 86400 IN DNSKEY 256 3 8 AQOcWJruwENIaapq3h3lKJlflLx6rWJz 2aKRBV6CBJRTxZu4ge2iDX164dQ7Hpc9 b8C9z2gqWyx1XyjvbQisgSid24voeUHQ gD0weedVDQjD6B9By7zMI6Yz+cM/w6H8 zB8ZRn6qZuWZAxFOjKvzoz+3vf32tyZE 7QmLFnXDgQpFxw==
+com. 86400 IN DNSKEY 257 3 8 AQPDzldNmMvZFX4NcNJ0uEnKDg7tmv/F 3MyQR0lpBmVcNcsIszxNFxsBfKNW9JYC Yqpik8366LE7VbIcNRzfp2h9OO8HRl+H +E08zauK8k7evWEmu/6od+2boggPoiEf GNyvNPaSI7FOIroDsnw/taggzHRX1Z7S OiOiPWPNIwSUyWOZ79VmcQ1GLkC6NlYv G3HwYmynQv6oFwGv/KELSw7ZSdrbTQ0H XvZbqMUI7BaMskmvgm1G7oKZ1YiF7O9i oVNc0+7ASbqmZN7Z98EGU/Qh2K/BgUe8 Hs0XVcdPKrtyYnoQHd2ynKPcMMlTEih2 /2HDHjRPJ2aywIpKNnv4oPo/
+com. 86400 IN RRSIG DNSKEY 8 1 86400 20190706182533 20190621182033 30909 com. v4xbl08Oyis8hHQ/7k9DuSLa75uMshqc V4783gXEEq1+dbgwBct8I2Td4+9mjIql fD1UO6Wu6VSYUtef39VQe4DuIWqtRrh/ WA/EOrrEY5Qieem9LTPL/zHWGQiILaHz CUHk1iUGFyZy4IRnZPkigTYKm1M7ZRXv qTTYSLemVZsna2/siDVYAdAhXWvJHQGl DkT3WDAvryFPpuEOrhUWkfhWAGy/ZsmD 87OiTX50TG/3ISEqFyzow/GZjViZnG5C tBmwdX/E8CIN6lVJV3LU3bMRYmuAHYEE lM+lVKAEyooxuRBNOdtZHD9tM8V6cfyd t89aE9LaiSn1DsFjUqFu/A==
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+gtld-servers.net. IN DS
+SECTION AUTHORITY
+5QDO29Q2PS5ARBKHB6R0BRN6NDSTSN90.net. 86400 IN NSEC3 1 1 0 - 5qdppotuk27kkp9ligtrb0k1cbvm9cim NS DS RRSIG
+5QDO29Q2PS5ARBKHB6R0BRN6NDSTSN90.net. 86400 IN RRSIG NSEC3 8 2 86400 20190629054715 20190622043715 2129 net. fvRKJkn9D2H3DFGE0zpk/tAkyjaoEZY4 4TkN6XtCAibjzQS8R0SCaXmZlQQujnjG wp0Rjhy0gMQaFUrJ8QuUbJSDZQaicAl7 pCESVKd95GZOSgi07BXSKwdUMAPROSjz gDkYGzHcUB5Kfe23gkL2eQ05YVigHYhI l0YCHui1wHE=
+A1RT98BS5QGC9NFI51S9HCI47ULJG6JH.net. 86400 IN NSEC3 1 1 0 - a1ruuffjkct2q54p78f8ejgj8jbk7i8b NS SOA RRSIG DNSKEY NSEC3PARAM
+A1RT98BS5QGC9NFI51S9HCI47ULJG6JH.net. 86400 IN RRSIG NSEC3 8 2 86400 20190702055539 20190625044539 2129 net. KgEWjLXuYdPBhlNh2epfnKU879hg4GGf F4m4Fo7ZW+S3uhNqq8pF7sMJCvSs8ZZA Ctcm88XThCeIAxDxLZ5moOlMIWaweVX3 7B7s3mw+3K0cnkYF6J4FqBO8o7x6J3i2 c6kxI3q0DKub23GcXpWZu3x2yIkWuN0I ZgceikGAPpM=
+net. 900 IN RRSIG SOA 8 1 900 20190702140916 20190625125916 2129 net. cMaAZOeBq2v9urE/L5RZEBRSTmY4/MMJ ADm+GUhaqP3FQ0RD3fO6IU7qdP3jCmlZ QmCl68ZVaMyZvVIcNcv7fokWbqTm9r4j 2NB0W9j/B/ZIOzCV4myDqaylU62tNTUA okGZMzclPCSd2n8ZDHZ3RysudhiZ/8WG FVdsHHtp67c=
+net. 900 IN SOA a.gtld-servers.net. nstld.verisign-grs.com. 1561471756 1800 900 604800 86400
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH subdomain
+ADJUST copy_id copy_query
+REPLY QR RD NOERROR
+SECTION QUESTION
+gtld-servers.net. IN NS
+SECTION AUTHORITY
+5QDO29Q2PS5ARBKHB6R0BRN6NDSTSN90.net. 86400 IN NSEC3 1 1 0 - 5qdppotuk27kkp9ligtrb0k1cbvm9cim NS DS RRSIG
+5QDO29Q2PS5ARBKHB6R0BRN6NDSTSN90.net. 86400 IN RRSIG NSEC3 8 2 86400 20190629054715 20190622043715 2129 net. fvRKJkn9D2H3DFGE0zpk/tAkyjaoEZY4 4TkN6XtCAibjzQS8R0SCaXmZlQQujnjG wp0Rjhy0gMQaFUrJ8QuUbJSDZQaicAl7 pCESVKd95GZOSgi07BXSKwdUMAPROSjz gDkYGzHcUB5Kfe23gkL2eQ05YVigHYhI l0YCHui1wHE=
+A1RT98BS5QGC9NFI51S9HCI47ULJG6JH.net. 86400 IN NSEC3 1 1 0 - a1ruuffjkct2q54p78f8ejgj8jbk7i8b NS SOA RRSIG DNSKEY NSEC3PARAM
+A1RT98BS5QGC9NFI51S9HCI47ULJG6JH.net. 86400 IN RRSIG NSEC3 8 2 86400 20190702055539 20190625044539 2129 net. KgEWjLXuYdPBhlNh2epfnKU879hg4GGf F4m4Fo7ZW+S3uhNqq8pF7sMJCvSs8ZZA Ctcm88XThCeIAxDxLZ5moOlMIWaweVX3 7B7s3mw+3K0cnkYF6J4FqBO8o7x6J3i2 c6kxI3q0DKub23GcXpWZu3x2yIkWuN0I ZgceikGAPpM=
+gtld-servers.net. 172800 IN NS av1.nstld.com.
+gtld-servers.net. 172800 IN NS av2.nstld.com.
+gtld-servers.net. 172800 IN NS av3.nstld.com.
+gtld-servers.net. 172800 IN NS av4.nstld.com.
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH subdomain
+ADJUST copy_id copy_query
+REPLY QR RD NOERROR
+SECTION QUESTION
+root-servers.net. IN NS
+SECTION AUTHORITY
+A1RT98BS5QGC9NFI51S9HCI47ULJG6JH.net. 86400 IN NSEC3 1 1 0 - a1ruuffjkct2q54p78f8ejgj8jbk7i8b NS SOA RRSIG DNSKEY NSEC3PARAM
+A1RT98BS5QGC9NFI51S9HCI47ULJG6JH.net. 86400 IN RRSIG NSEC3 8 2 86400 20190702055539 20190625044539 2129 net. KgEWjLXuYdPBhlNh2epfnKU879hg4GGf F4m4Fo7ZW+S3uhNqq8pF7sMJCvSs8ZZA Ctcm88XThCeIAxDxLZ5moOlMIWaweVX3 7B7s3mw+3K0cnkYF6J4FqBO8o7x6J3i2 c6kxI3q0DKub23GcXpWZu3x2yIkWuN0I ZgceikGAPpM=
+T2UF21DR03E0BNPB42UQMVUF38P2TA8D.net. 86400 IN NSEC3 1 1 0 - t2ukct9k5i0uhv7b3m3na6jaigdjm0gr NS DS RRSIG
+T2UF21DR03E0BNPB42UQMVUF38P2TA8D.net. 86400 IN RRSIG NSEC3 8 2 86400 20190630054523 20190623043523 2129 net. adpeQf+K6Hr5amhmF9DNK56LVWWnfGHK Dz9t9e7swG/P+4clc4yMKmUvK0OF9aTA kBzDwnzeB+FT+nsg1cWdibs4559AKQCL RtNErPhZRMojUFo6TLM9lQoXhv9i5rZB AJGmirHgSwiAvaUK7tgxX3nr1Atahyew iwHDQIVPhw4=
+root-servers.net. 172800 IN NS a.root-servers.net.
+root-servers.net. 172800 IN NS b.root-servers.net.
+root-servers.net. 172800 IN NS c.root-servers.net.
+root-servers.net. 172800 IN NS d.root-servers.net.
+root-servers.net. 172800 IN NS e.root-servers.net.
+root-servers.net. 172800 IN NS f.root-servers.net.
+root-servers.net. 172800 IN NS g.root-servers.net.
+root-servers.net. 172800 IN NS h.root-servers.net.
+root-servers.net. 172800 IN NS i.root-servers.net.
+root-servers.net. 172800 IN NS j.root-servers.net.
+root-servers.net. 172800 IN NS k.root-servers.net.
+root-servers.net. 172800 IN NS l.root-servers.net.
+root-servers.net. 172800 IN NS m.root-servers.net.
+SECTION ADDITIONAL
+a.root-servers.net. 172800 IN A 198.41.0.4
+a.root-servers.net. 172800 IN AAAA 2001:503:ba3e::2:30
+b.root-servers.net. 172800 IN A 199.9.14.201
+b.root-servers.net. 172800 IN AAAA 2001:500:200::b
+c.root-servers.net. 172800 IN A 192.33.4.12
+c.root-servers.net. 172800 IN AAAA 2001:500:2::c
+d.root-servers.net. 172800 IN A 199.7.91.13
+d.root-servers.net. 172800 IN AAAA 2001:500:2d::d
+e.root-servers.net. 172800 IN A 192.203.230.10
+e.root-servers.net. 172800 IN AAAA 2001:500:a8::e
+f.root-servers.net. 172800 IN A 192.5.5.241
+f.root-servers.net. 172800 IN AAAA 2001:500:2f::f
+g.root-servers.net. 172800 IN A 192.112.36.4
+g.root-servers.net. 172800 IN AAAA 2001:500:12::d0d
+h.root-servers.net. 172800 IN A 198.97.190.53
+h.root-servers.net. 172800 IN AAAA 2001:500:1::53
+i.root-servers.net. 172800 IN A 192.36.148.17
+i.root-servers.net. 172800 IN AAAA 2001:7fe::53
+j.root-servers.net. 172800 IN A 192.58.128.30
+j.root-servers.net. 172800 IN AAAA 2001:503:c27::2:30
+k.root-servers.net. 172800 IN A 193.0.14.129
+k.root-servers.net. 172800 IN AAAA 2001:7fd::1
+l.root-servers.net. 172800 IN A 199.7.83.42
+l.root-servers.net. 172800 IN AAAA 2001:500:9f::42
+m.root-servers.net. 172800 IN A 202.12.27.33
+m.root-servers.net. 172800 IN AAAA 2001:dc3::35
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH subdomain
+ADJUST copy_id copy_query
+REPLY QR RD NOERROR
+SECTION QUESTION
+nstld.com. IN NS
+SECTION AUTHORITY
+5V12UURISSGGLPAS52GE1V3R0V7KR5BS.com. 86400 IN NSEC3 1 1 0 - 5v13q049b9ittui4fbdtm34dtev47bgj NS DS RRSIG
+5V12UURISSGGLPAS52GE1V3R0V7KR5BS.com. 86400 IN RRSIG NSEC3 8 2 86400 20190630044250 20190623033250 3800 com. NlBOkX84YgGooJJ2vp+Z/O16Vkz6z1gC Jy1Va3fJyEXfZr/GIm8J3KJ6Eq+xxp1A x3ZWxwUjNH3TGUEme7pDrmusqRpx/TZF Za3dVAYIvsaVgIWtDCn4BLBPrg0HXcon HE60KLgWGQmezzFKrNsy5Tzz9TajUSgQ uOTQHB7TFDg=
+CK0POJMG874LJREF7EFN8430QVIT8BSM.com. 86400 IN NSEC3 1 1 0 - ck0q1gin43n1arrc9osm6qpqr81h5m9a NS SOA RRSIG DNSKEY NSEC3PARAM
+CK0POJMG874LJREF7EFN8430QVIT8BSM.com. 86400 IN RRSIG NSEC3 8 2 86400 20190702044530 20190625033530 3800 com. BMWhk6USUrb7TNJ3dSObn8QEPWvpzedW kP9i4RRPz7V9c2yVPmHSPt29QKsHOYTg iF4uyHt+K8RK8DBIziB19nrOjbb8iRDY 7m5koEj/OrS2peMuF6rqRRmkI6SY/ACy XHb/hRGE4tZd2gThNb7evZkk02IVuhEo njO3NBjCrsw=
+nstld.com. 172800 IN NS av1.nstld.com.
+nstld.com. 172800 IN NS av2.nstld.com.
+nstld.com. 172800 IN NS av3.nstld.com.
+nstld.com. 172800 IN NS av4.nstld.com.
+SECTION ADDITIONAL
+av1.nstld.com. 172800 IN A 192.42.177.30
+av1.nstld.com. 172800 IN AAAA 2001:500:124::30
+av2.nstld.com. 172800 IN A 192.42.178.30
+av2.nstld.com. 172800 IN AAAA 2001:500:125::30
+av3.nstld.com. 172800 IN A 192.82.133.30
+av3.nstld.com. 172800 IN AAAA 2001:500:126::30
+av4.nstld.com. 172800 IN A 192.82.134.30
+av4.nstld.com. 172800 IN AAAA 2001:500:127::30
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH subdomain
+ADJUST copy_id copy_query
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+net. IN NS
+SECTION ANSWER
+net. 172800 IN NS a.gtld-servers.net.
+net. 172800 IN NS b.gtld-servers.net.
+net. 172800 IN NS c.gtld-servers.net.
+net. 172800 IN NS d.gtld-servers.net.
+net. 172800 IN NS e.gtld-servers.net.
+net. 172800 IN NS f.gtld-servers.net.
+net. 172800 IN NS g.gtld-servers.net.
+net. 172800 IN NS h.gtld-servers.net.
+net. 172800 IN NS i.gtld-servers.net.
+net. 172800 IN NS j.gtld-servers.net.
+net. 172800 IN NS k.gtld-servers.net.
+net. 172800 IN NS l.gtld-servers.net.
+net. 172800 IN NS m.gtld-servers.net.
+net. 172800 IN RRSIG NS 8 1 172800 20190630055417 20190623044417 2129 net. WUAzfzoslC7YpzfY7qJ+vPaYpL/TN1fq Ak97qaEsQbPEka9AfUyL/ZKgGucOrDmB e0GK55jGT1B1XXiQasdlB8/SThSPm+Oc V/aQ8zUopPJ6gzCCRfEZOWCRvRbXa3am f6apMdig+NSxXgYQpVjZmka8XX8xDJar 3c4G5gZS9rA=
+SECTION ADDITIONAL
+a.gtld-servers.net. 172800 IN A 192.5.6.30
+a.gtld-servers.net. 172800 IN AAAA 2001:503:a83e::2:30
+b.gtld-servers.net. 172800 IN A 192.33.14.30
+b.gtld-servers.net. 172800 IN AAAA 2001:503:231d::2:30
+c.gtld-servers.net. 172800 IN A 192.26.92.30
+c.gtld-servers.net. 172800 IN AAAA 2001:503:83eb::30
+d.gtld-servers.net. 172800 IN A 192.31.80.30
+d.gtld-servers.net. 172800 IN AAAA 2001:500:856e::30
+e.gtld-servers.net. 172800 IN A 192.12.94.30
+e.gtld-servers.net. 172800 IN AAAA 2001:502:1ca1::30
+f.gtld-servers.net. 172800 IN A 192.35.51.30
+f.gtld-servers.net. 172800 IN AAAA 2001:503:d414::30
+g.gtld-servers.net. 172800 IN A 192.42.93.30
+g.gtld-servers.net. 172800 IN AAAA 2001:503:eea3::30
+h.gtld-servers.net. 172800 IN A 192.54.112.30
+h.gtld-servers.net. 172800 IN AAAA 2001:502:8cc::30
+i.gtld-servers.net. 172800 IN A 192.43.172.30
+i.gtld-servers.net. 172800 IN AAAA 2001:503:39c1::30
+j.gtld-servers.net. 172800 IN A 192.48.79.30
+j.gtld-servers.net. 172800 IN AAAA 2001:502:7094::30
+k.gtld-servers.net. 172800 IN A 192.52.178.30
+k.gtld-servers.net. 172800 IN AAAA 2001:503:d2d::30
+l.gtld-servers.net. 172800 IN A 192.41.162.30
+l.gtld-servers.net. 172800 IN AAAA 2001:500:d937::30
+m.gtld-servers.net. 172800 IN A 192.55.83.30
+m.gtld-servers.net. 172800 IN AAAA 2001:501:b1f9::30
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH subdomain
+ADJUST copy_id copy_query
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+com. IN NS
+SECTION ANSWER
+com. 172800 IN NS a.gtld-servers.net.
+com. 172800 IN NS b.gtld-servers.net.
+com. 172800 IN NS c.gtld-servers.net.
+com. 172800 IN NS d.gtld-servers.net.
+com. 172800 IN NS e.gtld-servers.net.
+com. 172800 IN NS f.gtld-servers.net.
+com. 172800 IN NS g.gtld-servers.net.
+com. 172800 IN NS h.gtld-servers.net.
+com. 172800 IN NS i.gtld-servers.net.
+com. 172800 IN NS j.gtld-servers.net.
+com. 172800 IN NS k.gtld-servers.net.
+com. 172800 IN NS l.gtld-servers.net.
+com. 172800 IN NS m.gtld-servers.net.
+com. 172800 IN RRSIG NS 8 1 172800 20190702044530 20190625033530 3800 com. F4MEGl13z9h8iv22sko8S8/JjSskipqt COrmfpx4p5XeRutUOpr/6wAEdSXWJ7yu 5Z/PMTBDjTo37WxfEhyvvYyiOLTzYOf+ AvFeeGDAxdOAlfjQ+6etggDPz1bsqIhE 2FX5i7dhfk0WYshBIUqCJmmPMdnVgLNN Bh4zYoT5irQ=
+SECTION ADDITIONAL
+a.gtld-servers.net. 172800 IN A 192.5.6.30
+a.gtld-servers.net. 172800 IN AAAA 2001:503:a83e::2:30
+b.gtld-servers.net. 172800 IN A 192.33.14.30
+b.gtld-servers.net. 172800 IN AAAA 2001:503:231d::2:30
+c.gtld-servers.net. 172800 IN A 192.26.92.30
+c.gtld-servers.net. 172800 IN AAAA 2001:503:83eb::30
+d.gtld-servers.net. 172800 IN A 192.31.80.30
+d.gtld-servers.net. 172800 IN AAAA 2001:500:856e::30
+e.gtld-servers.net. 172800 IN A 192.12.94.30
+e.gtld-servers.net. 172800 IN AAAA 2001:502:1ca1::30
+f.gtld-servers.net. 172800 IN A 192.35.51.30
+f.gtld-servers.net. 172800 IN AAAA 2001:503:d414::30
+g.gtld-servers.net. 172800 IN A 192.42.93.30
+g.gtld-servers.net. 172800 IN AAAA 2001:503:eea3::30
+h.gtld-servers.net. 172800 IN A 192.54.112.30
+h.gtld-servers.net. 172800 IN AAAA 2001:502:8cc::30
+i.gtld-servers.net. 172800 IN A 192.43.172.30
+i.gtld-servers.net. 172800 IN AAAA 2001:503:39c1::30
+j.gtld-servers.net. 172800 IN A 192.48.79.30
+j.gtld-servers.net. 172800 IN AAAA 2001:502:7094::30
+k.gtld-servers.net. 172800 IN A 192.52.178.30
+k.gtld-servers.net. 172800 IN AAAA 2001:503:d2d::30
+l.gtld-servers.net. 172800 IN A 192.41.162.30
+l.gtld-servers.net. 172800 IN AAAA 2001:500:d937::30
+m.gtld-servers.net. 172800 IN A 192.55.83.30
+m.gtld-servers.net. 172800 IN AAAA 2001:501:b1f9::30
+ENTRY_END
+
+
+
+
+RANGE_END
+
+
+
+; Group's zones:
+;	gtld-servers.net.
+;	nstld.com.
+; Server names:
+;	av1.nstld.com.
+;	av2.nstld.com.
+;	av3.nstld.com.
+;	av4.nstld.com.
+RANGE_BEGIN 0 1000
+	ADDRESS 192.42.178.30
+	ADDRESS 2001:500:125::30
+	ADDRESS 192.82.133.30
+	ADDRESS 192.42.177.30
+	ADDRESS 2001:500:124::30
+	ADDRESS 192.82.134.30
+	ADDRESS 2001:500:126::30
+	ADDRESS 2001:500:127::30
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+h.gtld-servers.net. IN A
+SECTION ANSWER
+h.gtld-servers.net. 86400 IN A 192.54.112.30
+SECTION AUTHORITY
+gtld-servers.net. 86400 IN NS av1.nstld.com.
+gtld-servers.net. 86400 IN NS av2.nstld.com.
+gtld-servers.net. 86400 IN NS av3.nstld.com.
+gtld-servers.net. 86400 IN NS av4.nstld.com.
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+i.gtld-servers.net. IN AAAA
+SECTION ANSWER
+i.gtld-servers.net. 86400 IN AAAA 2001:503:39c1::30
+SECTION AUTHORITY
+gtld-servers.net. 86400 IN NS av1.nstld.com.
+gtld-servers.net. 86400 IN NS av2.nstld.com.
+gtld-servers.net. 86400 IN NS av3.nstld.com.
+gtld-servers.net. 86400 IN NS av4.nstld.com.
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+av3.nstld.com. IN A
+SECTION ANSWER
+av3.nstld.com. 300 IN A 192.82.133.30
+SECTION AUTHORITY
+nstld.com. 86400 IN NS av1.nstld.com.
+nstld.com. 86400 IN NS av2.nstld.com.
+nstld.com. 86400 IN NS av3.nstld.com.
+nstld.com. 86400 IN NS av4.nstld.com.
+SECTION ADDITIONAL
+av1.nstld.com. 300 IN A 192.42.177.30
+av1.nstld.com. 300 IN AAAA 2001:500:124::30
+av2.nstld.com. 300 IN A 192.42.178.30
+av2.nstld.com. 300 IN AAAA 2001:500:125::30
+av3.nstld.com. 300 IN AAAA 2001:500:126::30
+av4.nstld.com. 300 IN A 192.82.134.30
+av4.nstld.com. 300 IN AAAA 2001:500:127::30
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+av1.nstld.com. IN A
+SECTION ANSWER
+av1.nstld.com. 300 IN A 192.42.177.30
+SECTION AUTHORITY
+nstld.com. 86400 IN NS av1.nstld.com.
+nstld.com. 86400 IN NS av2.nstld.com.
+nstld.com. 86400 IN NS av3.nstld.com.
+nstld.com. 86400 IN NS av4.nstld.com.
+SECTION ADDITIONAL
+av1.nstld.com. 300 IN AAAA 2001:500:124::30
+av2.nstld.com. 300 IN A 192.42.178.30
+av2.nstld.com. 300 IN AAAA 2001:500:125::30
+av3.nstld.com. 300 IN A 192.82.133.30
+av3.nstld.com. 300 IN AAAA 2001:500:126::30
+av4.nstld.com. 300 IN A 192.82.134.30
+av4.nstld.com. 300 IN AAAA 2001:500:127::30
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+j.gtld-servers.net. IN AAAA
+SECTION ANSWER
+j.gtld-servers.net. 86400 IN AAAA 2001:502:7094::30
+SECTION AUTHORITY
+gtld-servers.net. 86400 IN NS av1.nstld.com.
+gtld-servers.net. 86400 IN NS av2.nstld.com.
+gtld-servers.net. 86400 IN NS av3.nstld.com.
+gtld-servers.net. 86400 IN NS av4.nstld.com.
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+av2.nstld.com. IN AAAA
+SECTION ANSWER
+av2.nstld.com. 300 IN AAAA 2001:500:125::30
+SECTION AUTHORITY
+nstld.com. 86400 IN NS av1.nstld.com.
+nstld.com. 86400 IN NS av2.nstld.com.
+nstld.com. 86400 IN NS av3.nstld.com.
+nstld.com. 86400 IN NS av4.nstld.com.
+SECTION ADDITIONAL
+av1.nstld.com. 300 IN A 192.42.177.30
+av1.nstld.com. 300 IN AAAA 2001:500:124::30
+av2.nstld.com. 300 IN A 192.42.178.30
+av3.nstld.com. 300 IN A 192.82.133.30
+av3.nstld.com. 300 IN AAAA 2001:500:126::30
+av4.nstld.com. 300 IN A 192.82.134.30
+av4.nstld.com. 300 IN AAAA 2001:500:127::30
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+k.gtld-servers.net. IN AAAA
+SECTION ANSWER
+k.gtld-servers.net. 86400 IN AAAA 2001:503:d2d::30
+SECTION AUTHORITY
+gtld-servers.net. 86400 IN NS av1.nstld.com.
+gtld-servers.net. 86400 IN NS av2.nstld.com.
+gtld-servers.net. 86400 IN NS av3.nstld.com.
+gtld-servers.net. 86400 IN NS av4.nstld.com.
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+av1.nstld.com. IN NS
+SECTION AUTHORITY
+nstld.com. 86400 IN SOA av4.nstld.com. nstld.verisign-grs.com. 2018073100 7200 900 1209600 86400
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+f.gtld-servers.net. IN AAAA
+SECTION ANSWER
+f.gtld-servers.net. 86400 IN AAAA 2001:503:d414::30
+SECTION AUTHORITY
+gtld-servers.net. 86400 IN NS av1.nstld.com.
+gtld-servers.net. 86400 IN NS av2.nstld.com.
+gtld-servers.net. 86400 IN NS av3.nstld.com.
+gtld-servers.net. 86400 IN NS av4.nstld.com.
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+j.gtld-servers.net. IN NS
+SECTION AUTHORITY
+gtld-servers.net. 86400 IN SOA av4.nstld.com. nstld.verisign-grs.com. 2017061500 3600 900 1209600 86400
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+c.gtld-servers.net. IN NS
+SECTION AUTHORITY
+gtld-servers.net. 86400 IN SOA av4.nstld.com. nstld.verisign-grs.com. 2017061500 3600 900 1209600 86400
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+l.gtld-servers.net. IN AAAA
+SECTION ANSWER
+l.gtld-servers.net. 86400 IN AAAA 2001:500:d937::30
+SECTION AUTHORITY
+gtld-servers.net. 86400 IN NS av1.nstld.com.
+gtld-servers.net. 86400 IN NS av2.nstld.com.
+gtld-servers.net. 86400 IN NS av3.nstld.com.
+gtld-servers.net. 86400 IN NS av4.nstld.com.
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+b.gtld-servers.net. IN NS
+SECTION AUTHORITY
+gtld-servers.net. 86400 IN SOA av4.nstld.com. nstld.verisign-grs.com. 2017061500 3600 900 1209600 86400
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+f.gtld-servers.net. IN A
+SECTION ANSWER
+f.gtld-servers.net. 86400 IN A 192.35.51.30
+SECTION AUTHORITY
+gtld-servers.net. 86400 IN NS av1.nstld.com.
+gtld-servers.net. 86400 IN NS av2.nstld.com.
+gtld-servers.net. 86400 IN NS av3.nstld.com.
+gtld-servers.net. 86400 IN NS av4.nstld.com.
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+e.gtld-servers.net. IN NS
+SECTION AUTHORITY
+gtld-servers.net. 86400 IN SOA av4.nstld.com. nstld.verisign-grs.com. 2017061500 3600 900 1209600 86400
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+i.gtld-servers.net. IN A
+SECTION ANSWER
+i.gtld-servers.net. 86400 IN A 192.43.172.30
+SECTION AUTHORITY
+gtld-servers.net. 86400 IN NS av1.nstld.com.
+gtld-servers.net. 86400 IN NS av2.nstld.com.
+gtld-servers.net. 86400 IN NS av3.nstld.com.
+gtld-servers.net. 86400 IN NS av4.nstld.com.
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+d.gtld-servers.net. IN AAAA
+SECTION ANSWER
+d.gtld-servers.net. 86400 IN AAAA 2001:500:856e::30
+SECTION AUTHORITY
+gtld-servers.net. 86400 IN NS av1.nstld.com.
+gtld-servers.net. 86400 IN NS av2.nstld.com.
+gtld-servers.net. 86400 IN NS av3.nstld.com.
+gtld-servers.net. 86400 IN NS av4.nstld.com.
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+m.gtld-servers.net. IN NS
+SECTION AUTHORITY
+gtld-servers.net. 86400 IN SOA av4.nstld.com. nstld.verisign-grs.com. 2017061500 3600 900 1209600 86400
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+av3.nstld.com. IN NS
+SECTION AUTHORITY
+nstld.com. 86400 IN SOA av4.nstld.com. nstld.verisign-grs.com. 2018073100 7200 900 1209600 86400
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+g.gtld-servers.net. IN A
+SECTION ANSWER
+g.gtld-servers.net. 86400 IN A 192.42.93.30
+SECTION AUTHORITY
+gtld-servers.net. 86400 IN NS av1.nstld.com.
+gtld-servers.net. 86400 IN NS av2.nstld.com.
+gtld-servers.net. 86400 IN NS av3.nstld.com.
+gtld-servers.net. 86400 IN NS av4.nstld.com.
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+j.gtld-servers.net. IN A
+SECTION ANSWER
+j.gtld-servers.net. 86400 IN A 192.48.79.30
+SECTION AUTHORITY
+gtld-servers.net. 86400 IN NS av1.nstld.com.
+gtld-servers.net. 86400 IN NS av2.nstld.com.
+gtld-servers.net. 86400 IN NS av3.nstld.com.
+gtld-servers.net. 86400 IN NS av4.nstld.com.
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+f.gtld-servers.net. IN NS
+SECTION AUTHORITY
+gtld-servers.net. 86400 IN SOA av4.nstld.com. nstld.verisign-grs.com. 2017061500 3600 900 1209600 86400
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+av2.nstld.com. IN NS
+SECTION AUTHORITY
+nstld.com. 86400 IN SOA av4.nstld.com. nstld.verisign-grs.com. 2018073100 7200 900 1209600 86400
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+h.gtld-servers.net. IN NS
+SECTION AUTHORITY
+gtld-servers.net. 86400 IN SOA av4.nstld.com. nstld.verisign-grs.com. 2017061500 3600 900 1209600 86400
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+d.gtld-servers.net. IN NS
+SECTION AUTHORITY
+gtld-servers.net. 86400 IN SOA av4.nstld.com. nstld.verisign-grs.com. 2017061500 3600 900 1209600 86400
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+av1.nstld.com. IN AAAA
+SECTION ANSWER
+av1.nstld.com. 300 IN AAAA 2001:500:124::30
+SECTION AUTHORITY
+nstld.com. 86400 IN NS av1.nstld.com.
+nstld.com. 86400 IN NS av2.nstld.com.
+nstld.com. 86400 IN NS av3.nstld.com.
+nstld.com. 86400 IN NS av4.nstld.com.
+SECTION ADDITIONAL
+av1.nstld.com. 300 IN A 192.42.177.30
+av2.nstld.com. 300 IN A 192.42.178.30
+av2.nstld.com. 300 IN AAAA 2001:500:125::30
+av3.nstld.com. 300 IN A 192.82.133.30
+av3.nstld.com. 300 IN AAAA 2001:500:126::30
+av4.nstld.com. 300 IN A 192.82.134.30
+av4.nstld.com. 300 IN AAAA 2001:500:127::30
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+k.gtld-servers.net. IN A
+SECTION ANSWER
+k.gtld-servers.net. 86400 IN A 192.52.178.30
+SECTION AUTHORITY
+gtld-servers.net. 86400 IN NS av1.nstld.com.
+gtld-servers.net. 86400 IN NS av2.nstld.com.
+gtld-servers.net. 86400 IN NS av3.nstld.com.
+gtld-servers.net. 86400 IN NS av4.nstld.com.
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+h.gtld-servers.net. IN AAAA
+SECTION ANSWER
+h.gtld-servers.net. 86400 IN AAAA 2001:502:8cc::30
+SECTION AUTHORITY
+gtld-servers.net. 86400 IN NS av1.nstld.com.
+gtld-servers.net. 86400 IN NS av2.nstld.com.
+gtld-servers.net. 86400 IN NS av3.nstld.com.
+gtld-servers.net. 86400 IN NS av4.nstld.com.
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+a.gtld-servers.net. IN AAAA
+SECTION ANSWER
+a.gtld-servers.net. 86400 IN AAAA 2001:503:a83e::2:30
+SECTION AUTHORITY
+gtld-servers.net. 86400 IN NS av1.nstld.com.
+gtld-servers.net. 86400 IN NS av2.nstld.com.
+gtld-servers.net. 86400 IN NS av3.nstld.com.
+gtld-servers.net. 86400 IN NS av4.nstld.com.
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+l.gtld-servers.net. IN NS
+SECTION AUTHORITY
+gtld-servers.net. 86400 IN SOA av4.nstld.com. nstld.verisign-grs.com. 2017061500 3600 900 1209600 86400
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+b.gtld-servers.net. IN AAAA
+SECTION ANSWER
+b.gtld-servers.net. 86400 IN AAAA 2001:503:231d::2:30
+SECTION AUTHORITY
+gtld-servers.net. 86400 IN NS av1.nstld.com.
+gtld-servers.net. 86400 IN NS av2.nstld.com.
+gtld-servers.net. 86400 IN NS av3.nstld.com.
+gtld-servers.net. 86400 IN NS av4.nstld.com.
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+l.gtld-servers.net. IN A
+SECTION ANSWER
+l.gtld-servers.net. 86400 IN A 192.41.162.30
+SECTION AUTHORITY
+gtld-servers.net. 86400 IN NS av1.nstld.com.
+gtld-servers.net. 86400 IN NS av2.nstld.com.
+gtld-servers.net. 86400 IN NS av3.nstld.com.
+gtld-servers.net. 86400 IN NS av4.nstld.com.
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+d.gtld-servers.net. IN A
+SECTION ANSWER
+d.gtld-servers.net. 86400 IN A 192.31.80.30
+SECTION AUTHORITY
+gtld-servers.net. 86400 IN NS av1.nstld.com.
+gtld-servers.net. 86400 IN NS av2.nstld.com.
+gtld-servers.net. 86400 IN NS av3.nstld.com.
+gtld-servers.net. 86400 IN NS av4.nstld.com.
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+e.gtld-servers.net. IN AAAA
+SECTION ANSWER
+e.gtld-servers.net. 86400 IN AAAA 2001:502:1ca1::30
+SECTION AUTHORITY
+gtld-servers.net. 86400 IN NS av1.nstld.com.
+gtld-servers.net. 86400 IN NS av2.nstld.com.
+gtld-servers.net. 86400 IN NS av3.nstld.com.
+gtld-servers.net. 86400 IN NS av4.nstld.com.
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+k.gtld-servers.net. IN NS
+SECTION AUTHORITY
+gtld-servers.net. 86400 IN SOA av4.nstld.com. nstld.verisign-grs.com. 2017061500 3600 900 1209600 86400
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+av3.nstld.com. IN AAAA
+SECTION ANSWER
+av3.nstld.com. 300 IN AAAA 2001:500:126::30
+SECTION AUTHORITY
+nstld.com. 86400 IN NS av1.nstld.com.
+nstld.com. 86400 IN NS av2.nstld.com.
+nstld.com. 86400 IN NS av3.nstld.com.
+nstld.com. 86400 IN NS av4.nstld.com.
+SECTION ADDITIONAL
+av1.nstld.com. 300 IN A 192.42.177.30
+av1.nstld.com. 300 IN AAAA 2001:500:124::30
+av2.nstld.com. 300 IN A 192.42.178.30
+av2.nstld.com. 300 IN AAAA 2001:500:125::30
+av3.nstld.com. 300 IN A 192.82.133.30
+av4.nstld.com. 300 IN A 192.82.134.30
+av4.nstld.com. 300 IN AAAA 2001:500:127::30
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+a.gtld-servers.net. IN A
+SECTION ANSWER
+a.gtld-servers.net. 86400 IN A 192.5.6.30
+SECTION AUTHORITY
+gtld-servers.net. 86400 IN NS av1.nstld.com.
+gtld-servers.net. 86400 IN NS av2.nstld.com.
+gtld-servers.net. 86400 IN NS av3.nstld.com.
+gtld-servers.net. 86400 IN NS av4.nstld.com.
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+av4.nstld.com. IN AAAA
+SECTION ANSWER
+av4.nstld.com. 300 IN AAAA 2001:500:127::30
+SECTION AUTHORITY
+nstld.com. 86400 IN NS av1.nstld.com.
+nstld.com. 86400 IN NS av2.nstld.com.
+nstld.com. 86400 IN NS av3.nstld.com.
+nstld.com. 86400 IN NS av4.nstld.com.
+SECTION ADDITIONAL
+av1.nstld.com. 300 IN A 192.42.177.30
+av1.nstld.com. 300 IN AAAA 2001:500:124::30
+av2.nstld.com. 300 IN A 192.42.178.30
+av2.nstld.com. 300 IN AAAA 2001:500:125::30
+av3.nstld.com. 300 IN A 192.82.133.30
+av3.nstld.com. 300 IN AAAA 2001:500:126::30
+av4.nstld.com. 300 IN A 192.82.134.30
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+g.gtld-servers.net. IN AAAA
+SECTION ANSWER
+g.gtld-servers.net. 86400 IN AAAA 2001:503:eea3::30
+SECTION AUTHORITY
+gtld-servers.net. 86400 IN NS av1.nstld.com.
+gtld-servers.net. 86400 IN NS av2.nstld.com.
+gtld-servers.net. 86400 IN NS av3.nstld.com.
+gtld-servers.net. 86400 IN NS av4.nstld.com.
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+c.gtld-servers.net. IN A
+SECTION ANSWER
+c.gtld-servers.net. 86400 IN A 192.26.92.30
+SECTION AUTHORITY
+gtld-servers.net. 86400 IN NS av1.nstld.com.
+gtld-servers.net. 86400 IN NS av2.nstld.com.
+gtld-servers.net. 86400 IN NS av3.nstld.com.
+gtld-servers.net. 86400 IN NS av4.nstld.com.
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+av4.nstld.com. IN NS
+SECTION AUTHORITY
+nstld.com. 86400 IN SOA av4.nstld.com. nstld.verisign-grs.com. 2018073100 7200 900 1209600 86400
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+a.gtld-servers.net. IN NS
+SECTION AUTHORITY
+gtld-servers.net. 86400 IN SOA av4.nstld.com. nstld.verisign-grs.com. 2017061500 3600 900 1209600 86400
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+m.gtld-servers.net. IN AAAA
+SECTION ANSWER
+m.gtld-servers.net. 86400 IN AAAA 2001:501:b1f9::30
+SECTION AUTHORITY
+gtld-servers.net. 86400 IN NS av1.nstld.com.
+gtld-servers.net. 86400 IN NS av2.nstld.com.
+gtld-servers.net. 86400 IN NS av3.nstld.com.
+gtld-servers.net. 86400 IN NS av4.nstld.com.
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+m.gtld-servers.net. IN A
+SECTION ANSWER
+m.gtld-servers.net. 86400 IN A 192.55.83.30
+SECTION AUTHORITY
+gtld-servers.net. 86400 IN NS av1.nstld.com.
+gtld-servers.net. 86400 IN NS av2.nstld.com.
+gtld-servers.net. 86400 IN NS av3.nstld.com.
+gtld-servers.net. 86400 IN NS av4.nstld.com.
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+i.gtld-servers.net. IN NS
+SECTION AUTHORITY
+gtld-servers.net. 86400 IN SOA av4.nstld.com. nstld.verisign-grs.com. 2017061500 3600 900 1209600 86400
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+g.gtld-servers.net. IN NS
+SECTION AUTHORITY
+gtld-servers.net. 86400 IN SOA av4.nstld.com. nstld.verisign-grs.com. 2017061500 3600 900 1209600 86400
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+c.gtld-servers.net. IN AAAA
+SECTION ANSWER
+c.gtld-servers.net. 86400 IN AAAA 2001:503:83eb::30
+SECTION AUTHORITY
+gtld-servers.net. 86400 IN NS av1.nstld.com.
+gtld-servers.net. 86400 IN NS av2.nstld.com.
+gtld-servers.net. 86400 IN NS av3.nstld.com.
+gtld-servers.net. 86400 IN NS av4.nstld.com.
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+av2.nstld.com. IN A
+SECTION ANSWER
+av2.nstld.com. 300 IN A 192.42.178.30
+SECTION AUTHORITY
+nstld.com. 86400 IN NS av1.nstld.com.
+nstld.com. 86400 IN NS av2.nstld.com.
+nstld.com. 86400 IN NS av3.nstld.com.
+nstld.com. 86400 IN NS av4.nstld.com.
+SECTION ADDITIONAL
+av1.nstld.com. 300 IN A 192.42.177.30
+av1.nstld.com. 300 IN AAAA 2001:500:124::30
+av2.nstld.com. 300 IN AAAA 2001:500:125::30
+av3.nstld.com. 300 IN A 192.82.133.30
+av3.nstld.com. 300 IN AAAA 2001:500:126::30
+av4.nstld.com. 300 IN A 192.82.134.30
+av4.nstld.com. 300 IN AAAA 2001:500:127::30
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+av4.nstld.com. IN A
+SECTION ANSWER
+av4.nstld.com. 300 IN A 192.82.134.30
+SECTION AUTHORITY
+nstld.com. 86400 IN NS av1.nstld.com.
+nstld.com. 86400 IN NS av2.nstld.com.
+nstld.com. 86400 IN NS av3.nstld.com.
+nstld.com. 86400 IN NS av4.nstld.com.
+SECTION ADDITIONAL
+av1.nstld.com. 300 IN A 192.42.177.30
+av1.nstld.com. 300 IN AAAA 2001:500:124::30
+av2.nstld.com. 300 IN A 192.42.178.30
+av2.nstld.com. 300 IN AAAA 2001:500:125::30
+av3.nstld.com. 300 IN A 192.82.133.30
+av3.nstld.com. 300 IN AAAA 2001:500:126::30
+av4.nstld.com. 300 IN AAAA 2001:500:127::30
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+b.gtld-servers.net. IN A
+SECTION ANSWER
+b.gtld-servers.net. 86400 IN A 192.33.14.30
+SECTION AUTHORITY
+gtld-servers.net. 86400 IN NS av1.nstld.com.
+gtld-servers.net. 86400 IN NS av2.nstld.com.
+gtld-servers.net. 86400 IN NS av3.nstld.com.
+gtld-servers.net. 86400 IN NS av4.nstld.com.
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id 
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+e.gtld-servers.net. IN A
+SECTION ANSWER
+e.gtld-servers.net. 86400 IN A 192.12.94.30
+SECTION AUTHORITY
+gtld-servers.net. 86400 IN NS av1.nstld.com.
+gtld-servers.net. 86400 IN NS av2.nstld.com.
+gtld-servers.net. 86400 IN NS av3.nstld.com.
+gtld-servers.net. 86400 IN NS av4.nstld.com.
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH subdomain
+ADJUST copy_id copy_query
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+gtld-servers.net. IN NS
+SECTION ANSWER
+gtld-servers.net. 86400 IN NS av1.nstld.com.
+gtld-servers.net. 86400 IN NS av2.nstld.com.
+gtld-servers.net. 86400 IN NS av3.nstld.com.
+gtld-servers.net. 86400 IN NS av4.nstld.com.
+ENTRY_END
+
+
+ENTRY_BEGIN
+MATCH subdomain
+ADJUST copy_id copy_query
+REPLY QR AA RD NOERROR
+SECTION QUESTION
+nstld.com. IN NS
+SECTION ANSWER
+nstld.com. 86400 IN NS av1.nstld.com.
+nstld.com. 86400 IN NS av2.nstld.com.
+nstld.com. 86400 IN NS av3.nstld.com.
+nstld.com. 86400 IN NS av4.nstld.com.
+SECTION ADDITIONAL
+av1.nstld.com. 300 IN A 192.42.177.30
+av1.nstld.com. 300 IN AAAA 2001:500:124::30
+av2.nstld.com. 300 IN A 192.42.178.30
+av2.nstld.com. 300 IN AAAA 2001:500:125::30
+av3.nstld.com. 300 IN A 192.82.133.30
+av3.nstld.com. 300 IN AAAA 2001:500:126::30
+av4.nstld.com. 300 IN A 192.82.134.30
+av4.nstld.com. 300 IN AAAA 2001:500:127::30
+ENTRY_END
+
+
+
+
+RANGE_END
+
+
+
+
+
+; Sequence of queries made by browser
+
+; 1st query for AAAA
+STEP 10 QUERY
+ENTRY_BEGIN
+REPLY RD AD
+SECTION QUESTION
+csas.cz. IN AAAA
+ENTRY_END
+
+; answer for AAAA contains minimally covering NSEC3 answer with incorrect bitmap
+; it claims that csas.cz A RR is not present
+STEP 11 CHECK_ANSWER
+ENTRY_BEGIN
+MATCH opcode flags rcode question answer
+REPLY QR RD RA AD NOERROR
+SECTION QUESTION
+csas.cz. IN AAAA
+SECTION AUTHORITY
+csas.cz. 119 IN SOA ddnsa.csas.cz. domainservices.csas.cz. 2019061320 28800 1800 2592000 120
+ENTRY_END
+
+; 2nd query for A
+STEP 21 QUERY
+ENTRY_BEGIN
+REPLY RD AD
+SECTION QUESTION
+csas.cz. IN A
+ENTRY_END
+
+; check that A query gets an IP address
+; this answer would be empty
+; if minimally covering NSEC3 was not exempt from aggressive caching
+STEP 22 CHECK_ANSWER
+ENTRY_BEGIN
+MATCH opcode flags rcode question answer
+REPLY QR RD RA AD NOERROR
+SECTION QUESTION
+csas.cz. IN A
+SECTION ANSWER
+csas.cz. 120 IN A 194.50.240.198
+csas.cz. 120 IN A 194.50.240.70
+ENTRY_END
+
+SCENARIO_END
diff --git a/lib/cache/test.integr/deckard.yaml b/lib/cache/test.integr/deckard.yaml
new file mode 100644
index 0000000..df88f83
--- /dev/null
+++ b/lib/cache/test.integr/deckard.yaml
@@ -0,0 +1,13 @@
+# SPDX-License-Identifier: GPL-3.0-or-later
+programs:
+- name: kresd
+  binary: kresd
+  additional:
+    - --noninteractive
+  templates:
+    - lib/cache/test.integr/kresd_config.j2
+    - tests/integration/hints_zone.j2
+  configs:
+    - config
+    - hints
+noclean: True
diff --git a/lib/cache/test.integr/kresd_config.j2 b/lib/cache/test.integr/kresd_config.j2
new file mode 100644
index 0000000..7c3724b
--- /dev/null
+++ b/lib/cache/test.integr/kresd_config.j2
@@ -0,0 +1,69 @@
+-- SPDX-License-Identifier: GPL-3.0-or-later
+{% for TAF in TRUST_ANCHOR_FILES %}
+-- trust_anchors.add_file('{{TAF}}')
+{% endfor %}
+
+{% raw %}
+-- Disable RFC5011 TA update
+if ta_update then
+        modules.unload('ta_update')
+end
+
+-- Disable RFC8145 signaling, scenario doesn't provide expected answers
+if ta_signal_query then
+        modules.unload('ta_signal_query')
+end
+
+-- Disable RFC8109 priming, scenario doesn't provide expected answers
+if priming then
+        modules.unload('priming')
+end
+
+-- Disable this module because it make one priming query
+if detect_time_skew then
+        modules.unload('detect_time_skew')
+end
+
+_hint_root_file('hints')
+cache.size = 2*MB
+verbose(true)
+policy.add(policy.all(policy.DEBUG_ALWAYS))
+{% endraw %}
+
+net = { '{{SELF_ADDR}}' }
+
+{% if DO_IP6 == "true" %}
+net.ipv6 = true
+{% else %}
+net.ipv6 = false
+{% endif %}
+
+{% if DO_IP4 == "true" %}
+net.ipv4 = true
+{% else %}
+net.ipv4 = false
+{% endif %}
+
+{% if QMIN == "false" %}
+option('NO_MINIMIZE', true)
+{% else %}
+option('NO_MINIMIZE', false)
+{% endif %}
+
+
+-- Self-checks on globals
+assert(help() ~= nil)
+assert(worker.id ~= nil)
+-- Self-checks on facilities
+assert(cache.count() == 0)
+assert(cache.stats() ~= nil)
+assert(cache.backends() ~= nil)
+assert(worker.stats() ~= nil)
+assert(net.interfaces() ~= nil)
+-- Self-checks on loaded stuff
+assert(net.list()[1].transport.ip == '{{SELF_ADDR}}')
+assert(#modules.list() > 0)
+-- Self-check timers
+ev = event.recurrent(1 * sec, function (ev) return 1 end)
+event.cancel(ev)
+ev = event.after(0, function (ev) return 1 end)
diff --git a/lib/cache/util.h b/lib/cache/util.h
new file mode 100644
index 0000000..0a2f329
--- /dev/null
+++ b/lib/cache/util.h
@@ -0,0 +1,4 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+#include <libknot/packet/pkt.h>
+
+uint32_t packet_ttl(const knot_pkt_t *pkt, bool is_negative);
diff --git a/lib/cookies/alg_containers.c b/lib/cookies/alg_containers.c
new file mode 100644
index 0000000..491859b
--- /dev/null
+++ b/lib/cookies/alg_containers.c
@@ -0,0 +1,60 @@
+/*  Copyright (C) 2016-2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#include <assert.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+#include <libknot/cookies/alg-fnv64.h>
+
+#include "lib/cookies/alg_containers.h"
+#include "lib/cookies/alg_sha.h"
+
+const struct knot_cc_alg *kr_cc_alg_get(int id)
+{
+	/*
+	 * Client algorithm identifiers are used to index this array of
+	 * pointers.
+	 */
+	static const struct knot_cc_alg *const cc_algs[] = {
+		/* 0 */ &knot_cc_alg_fnv64,
+		/* 1 */ &knot_cc_alg_hmac_sha256_64
+	};
+
+	if (id >= 0 && id < 2) {
+		return cc_algs[id];
+	}
+
+	return NULL;
+}
+
+const knot_lookup_t kr_cc_alg_names[] = {
+	{ 0, "FNV-64" },
+	{ 1, "HMAC-SHA256-64" },
+	{ -1, NULL }
+};
+
+const struct knot_sc_alg *kr_sc_alg_get(int id)
+{
+	/*
+	 * Server algorithm identifiers are used to index this array of
+	 * pointers.
+	 */
+	static const struct knot_sc_alg *const sc_algs[] = {
+		/* 0 */ &knot_sc_alg_fnv64,
+		/* 1 */ &knot_sc_alg_hmac_sha256_64
+	};
+
+	if (id >= 0 && id < 2) {
+		return sc_algs[id];
+	}
+
+	return NULL;
+}
+
+const knot_lookup_t kr_sc_alg_names[] = {
+	{ 0, "FNV-64" },
+	{ 1, "HMAC-SHA256-64" },
+	{ -1, NULL }
+};
diff --git a/lib/cookies/alg_containers.h b/lib/cookies/alg_containers.h
new file mode 100644
index 0000000..3b50cca
--- /dev/null
+++ b/lib/cookies/alg_containers.h
@@ -0,0 +1,37 @@
+/*  Copyright (C) 2016-2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#pragma once
+
+#include <libknot/cookies/client.h>
+#include <libknot/cookies/server.h>
+#include <libknot/lookup.h>
+
+#include "lib/defines.h"
+
+/**
+ * @brief Returns pointer to client cookie algorithm.
+ *
+ * @param id algorithm identifier as defined by lookup table
+ * @return   pointer to algorithm structure with given id or NULL on error
+ */
+KR_EXPORT
+const struct knot_cc_alg *kr_cc_alg_get(int id);
+
+/** Binds client algorithm identifiers onto names. */
+KR_EXPORT
+extern const knot_lookup_t kr_cc_alg_names[];
+
+/**
+ * @brief Returns pointer to server cookie algorithm.
+ *
+ * @param id algorithm identifier as defined by lookup table
+ * @return   pointer to algorithm structure with given id or NULL on error
+ */
+KR_EXPORT
+const struct knot_sc_alg *kr_sc_alg_get(int id);
+
+/** Binds server algorithm identifiers onto names. */
+KR_EXPORT
+extern const knot_lookup_t kr_sc_alg_names[];
diff --git a/lib/cookies/alg_sha.c b/lib/cookies/alg_sha.c
new file mode 100644
index 0000000..37eafbc
--- /dev/null
+++ b/lib/cookies/alg_sha.c
@@ -0,0 +1,110 @@
+/*  Copyright (C) 2016-2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#include <assert.h>
+#include <nettle/hmac.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+#include <libknot/errcode.h>
+#include <libknot/rrtype/opt-cookie.h>
+
+#include "lib/cookies/alg_sha.h"
+#include "lib/utils.h"
+
+/**
+ * @brief Update hash value.
+ *
+ * @param ctx HMAC-SHA256 context to be updated.
+ * @param sa  Socket address.
+ */
+static inline void update_hash(struct hmac_sha256_ctx *ctx,
+                               const struct sockaddr *sa)
+{
+	assert(ctx && sa);
+
+	int addr_len = kr_inaddr_len(sa);
+	const uint8_t *addr = (uint8_t *)kr_inaddr(sa);
+
+	if (addr && addr_len > 0) {
+		hmac_sha256_update(ctx, addr_len, addr);
+	}
+}
+
+/**
+ * @brief Compute client cookie using HMAC-SHA256-64.
+ * @note At least one of the arguments must be non-null.
+ * @param input  input parameters
+ * @param cc_out buffer for computed client cookie
+ * @param cc_len buffer size
+ * @return Non-zero size of written data on success, 0 in case of a failure.
+ */
+static uint16_t cc_gen_hmac_sha256_64(const struct knot_cc_input *input,
+                                      uint8_t *cc_out, uint16_t cc_len)
+{
+	if (!knot_cc_input_is_valid(input) ||
+	    !cc_out || cc_len < KNOT_OPT_COOKIE_CLNT) {
+		return 0;
+	}
+
+	struct hmac_sha256_ctx ctx;
+	hmac_sha256_set_key(&ctx, input->secret_len, input->secret_data);
+
+	if (input->clnt_sockaddr) {
+		update_hash(&ctx, input->clnt_sockaddr);
+	}
+
+	if (input->srvr_sockaddr) {
+		update_hash(&ctx, input->srvr_sockaddr);
+	}
+
+	/* KNOT_OPT_COOKIE_CLNT <= SHA256_DIGEST_SIZE */
+
+	hmac_sha256_digest(&ctx, KNOT_OPT_COOKIE_CLNT, cc_out);
+
+	return KNOT_OPT_COOKIE_CLNT;
+}
+
+#define SRVR_HMAC_SHA256_64_HASH_SIZE 8
+
+/**
+ * @brief Compute server cookie hash using HMAC-SHA256-64).
+ * @note Server cookie = nonce | time | HMAC-SHA256-64( server secret, client cookie | nonce| time | client IP )
+ * @param input    data to compute cookie from
+ * @param hash_out hash output buffer
+ * @param hash_len buffer size
+ * @return Non-zero size of written data on success, 0 in case of a failure.
+ */
+static uint16_t sc_gen_hmac_sha256_64(const struct knot_sc_input *input,
+                                      uint8_t *hash_out, uint16_t hash_len)
+{
+	if (!knot_sc_input_is_valid(input) ||
+	    !hash_out || hash_len < SRVR_HMAC_SHA256_64_HASH_SIZE) {
+		return 0;
+	}
+
+	struct hmac_sha256_ctx ctx;
+	hmac_sha256_set_key(&ctx, input->srvr_data->secret_len,
+	                    input->srvr_data->secret_data);
+
+	hmac_sha256_update(&ctx, input->cc_len, input->cc);
+
+	if (input->nonce && input->nonce_len) {
+		hmac_sha256_update(&ctx, input->nonce_len, input->nonce);
+	}
+
+	if (input->srvr_data->clnt_sockaddr) {
+		update_hash(&ctx, input->srvr_data->clnt_sockaddr);
+	}
+
+	/* SRVR_HMAC_SHA256_64_HASH_SIZE < SHA256_DIGEST_SIZE */
+
+	hmac_sha256_digest(&ctx, SRVR_HMAC_SHA256_64_HASH_SIZE, hash_out);
+
+	return SRVR_HMAC_SHA256_64_HASH_SIZE;
+}
+
+const struct knot_cc_alg knot_cc_alg_hmac_sha256_64 = { KNOT_OPT_COOKIE_CLNT, cc_gen_hmac_sha256_64 };
+
+const struct knot_sc_alg knot_sc_alg_hmac_sha256_64 = { SRVR_HMAC_SHA256_64_HASH_SIZE, sc_gen_hmac_sha256_64 };
diff --git a/lib/cookies/alg_sha.h b/lib/cookies/alg_sha.h
new file mode 100644
index 0000000..de7a75a
--- /dev/null
+++ b/lib/cookies/alg_sha.h
@@ -0,0 +1,18 @@
+/*  Copyright (C) 2016-2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#pragma once
+
+#include <libknot/cookies/client.h>
+#include <libknot/cookies/server.h>
+
+#include "lib/defines.h"
+
+/* These structures are not meant to be part of public interface. */
+
+/** HMAC-SHA256-64 client cookie algorithm. */
+extern const struct knot_cc_alg knot_cc_alg_hmac_sha256_64;
+
+/** HMAC-SHA256-64 server cookie algorithm. */
+extern const struct knot_sc_alg knot_sc_alg_hmac_sha256_64;
diff --git a/lib/cookies/control.h b/lib/cookies/control.h
new file mode 100644
index 0000000..f977c94
--- /dev/null
+++ b/lib/cookies/control.h
@@ -0,0 +1,37 @@
+/*  Copyright (C) 2016-2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#pragma once
+
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+#include "lib/defines.h"
+
+/** Holds secret quantity. */
+struct kr_cookie_secret {
+	size_t size; /*!< Secret quantity size. */
+	uint8_t data[]; /*!< Secret quantity data. */
+};
+
+/** Holds settings that have direct influence on cookie values computation. */
+struct kr_cookie_comp {
+	struct kr_cookie_secret *secr; /*!< Secret data. */
+	int alg_id; /*!< Cookie algorithm identifier. */
+};
+
+/** Holds settings that control client/server cookie behaviour. */
+struct kr_cookie_settings {
+	bool enabled; /**< Enable/disables DNS cookies functionality. */
+
+	struct kr_cookie_comp current; /**< Current cookie settings. */
+	struct kr_cookie_comp recent; /**< Recent cookie settings. */
+};
+
+/** DNS cookies controlling structure. */
+struct kr_cookie_ctx {
+	struct kr_cookie_settings clnt; /**< Client settings. */
+	struct kr_cookie_settings srvr; /**< Server settings. */
+};
diff --git a/lib/cookies/helper.c b/lib/cookies/helper.c
new file mode 100644
index 0000000..55c4fbc
--- /dev/null
+++ b/lib/cookies/helper.c
@@ -0,0 +1,284 @@
+/*  Copyright (C) 2016-2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#include <assert.h>
+#include <libknot/rrtype/opt.h>
+#include <libknot/rrtype/opt-cookie.h>
+
+#include "lib/cookies/helper.h"
+#include "lib/defines.h"
+
+/**
+ * @brief Check whether there is a cached cookie that matches the current
+ *        client cookie.
+ */
+static const uint8_t *peek_and_check_cc(kr_cookie_lru_t *cache, const void *sa,
+                                        const uint8_t *cc, uint16_t cc_len)
+{
+	assert(cache && sa && cc && cc_len);
+
+	const uint8_t *cached_opt = kr_cookie_lru_get(cache, sa);
+	if (!cached_opt) {
+		return NULL;
+	}
+
+	const uint8_t *cached_cc = knot_edns_opt_get_data((uint8_t *) cached_opt);
+
+	if (cc_len == KNOT_OPT_COOKIE_CLNT &&
+	    0 == memcmp(cc, cached_cc, cc_len)) {
+		return cached_opt;
+	}
+
+	return NULL;
+}
+
+/**
+ * @brief Put a client cookie into the RR Set.
+ */
+static int opt_rr_put_cookie(knot_rrset_t *opt_rr, uint8_t *data,
+                             uint16_t data_len, knot_mm_t *mm)
+{
+	assert(opt_rr && data && data_len > 0);
+
+	const uint8_t *cc = NULL, *sc = NULL;
+	uint16_t cc_len = 0, sc_len = 0;
+
+	int ret = knot_edns_opt_cookie_parse(data, data_len, &cc, &cc_len,
+	                                     &sc, &sc_len);
+	if (ret != KNOT_EOK) {
+		return kr_error(EINVAL);
+	}
+	assert(data_len == cc_len + sc_len);
+
+	uint16_t cookies_size = data_len;
+	uint8_t *cookies_data = NULL;
+
+	ret = knot_edns_reserve_unique_option(opt_rr, KNOT_EDNS_OPTION_COOKIE,
+	                                      cookies_size, &cookies_data, mm);
+	if (ret != KNOT_EOK) {
+		return kr_error(EINVAL);
+	}
+	assert(cookies_data != NULL);
+
+	cookies_size = knot_edns_opt_cookie_write(cc, cc_len, sc, sc_len,
+	                                          cookies_data, cookies_size);
+	if (cookies_size == 0) {
+		return kr_error(EINVAL);
+	}
+	assert(cookies_size == data_len);
+
+	return kr_ok();
+}
+
+/**
+ * @brief Puts entire EDNS option into the RR Set.
+ */
+static int opt_rr_put_cookie_opt(knot_rrset_t *opt_rr, uint8_t *option, knot_mm_t *mm)
+{
+	assert(opt_rr && option);
+
+	uint16_t opt_code = knot_edns_opt_get_code(option);
+	if (opt_code != KNOT_EDNS_OPTION_COOKIE) {
+		return kr_error(EINVAL);
+	}
+
+	uint16_t opt_len = knot_edns_opt_get_length(option);
+	uint8_t *opt_data = knot_edns_opt_get_data(option);
+	if (!opt_data || opt_len == 0) {
+		return kr_error(EINVAL);
+	}
+
+	return opt_rr_put_cookie(opt_rr, opt_data, opt_len, mm);
+}
+
+int kr_request_put_cookie(const struct kr_cookie_comp *clnt_comp,
+                          kr_cookie_lru_t *cookie_cache,
+                          const struct sockaddr *clnt_sa,
+                          const struct sockaddr *srvr_sa,
+                          struct kr_request *req)
+{
+	if (!clnt_comp || !req) {
+		return kr_error(EINVAL);
+	}
+
+	if (!req->ctx->opt_rr) {
+		return kr_ok();
+	}
+
+	if (!clnt_comp->secr || (clnt_comp->alg_id < 0) || !cookie_cache) {
+		return kr_error(EINVAL);
+	}
+
+	/*
+	 * Generate client cookie from client address, server address and
+	 * secret quantity.
+	 */
+	struct knot_cc_input input = {
+		.clnt_sockaddr = clnt_sa,
+		.srvr_sockaddr = srvr_sa,
+		.secret_data = clnt_comp->secr->data,
+		.secret_len = clnt_comp->secr->size
+	};
+	uint8_t cc[KNOT_OPT_COOKIE_CLNT];
+	uint16_t cc_len = KNOT_OPT_COOKIE_CLNT;
+	const struct knot_cc_alg *cc_alg = kr_cc_alg_get(clnt_comp->alg_id);
+	if (!cc_alg) {
+		return kr_error(EINVAL);
+	}
+	assert(cc_alg->gen_func);
+	cc_len = cc_alg->gen_func(&input, cc, cc_len);
+	if (cc_len != KNOT_OPT_COOKIE_CLNT) {
+		return kr_error(EINVAL);
+	}
+
+	const uint8_t *cached_cookie = peek_and_check_cc(cookie_cache,
+	                                                 srvr_sa, cc, cc_len);
+
+	/* Add cookie option. */
+	int ret;
+	if (cached_cookie) {
+		ret = opt_rr_put_cookie_opt(req->ctx->opt_rr,
+		                            (uint8_t *)cached_cookie,
+		                            req->ctx->pool);
+	} else {
+		ret = opt_rr_put_cookie(req->ctx->opt_rr, cc, cc_len,
+		                        req->ctx->pool);
+	}
+
+	return ret;
+}
+
+int kr_answer_write_cookie(struct knot_sc_input *sc_input,
+                           const struct kr_nonce_input *nonce,
+                           const struct knot_sc_alg *alg, knot_pkt_t *pkt)
+{
+	if (!sc_input || !sc_input->cc || sc_input->cc_len == 0) {
+		return kr_error(EINVAL);
+	}
+
+	if (!sc_input->srvr_data || !sc_input->srvr_data->clnt_sockaddr ||
+	    !sc_input->srvr_data->secret_data ||
+	    !sc_input->srvr_data->secret_len) {
+		return kr_error(EINVAL);
+	}
+
+	if (!nonce) {
+		return kr_error(EINVAL);
+	}
+
+	if (!alg || !alg->hash_size || !alg->hash_func) {
+		return kr_error(EINVAL);
+	}
+
+	if (!pkt || !pkt->opt_rr) {
+		return kr_error(EINVAL);
+	}
+
+	uint16_t nonce_len = KR_NONCE_LEN;
+	uint16_t hash_len = alg->hash_size;
+
+	/*
+	 * Space for cookie is reserved inside the EDNS OPT RR of
+	 * the answer packet.
+	 */
+	uint8_t *cookie = NULL;
+	uint16_t cookie_len = knot_edns_opt_cookie_data_len(sc_input->cc_len,
+	                                                    nonce_len + hash_len);
+	if (cookie_len == 0) {
+		return kr_error(EINVAL);
+	}
+
+	int ret = knot_edns_reserve_unique_option(pkt->opt_rr,
+	                                          KNOT_EDNS_OPTION_COOKIE,
+	                                          cookie_len, &cookie,
+	                                          &pkt->mm);
+	if (ret != KNOT_EOK) {
+		return kr_error(ENOMEM);
+	}
+	assert(cookie != NULL);
+
+	/*
+	 * Function knot_edns_opt_cookie_data_len() returns the sum of its
+	 * parameters or zero. Anyway, let's check again.
+	 */
+	if (cookie_len < (sc_input->cc_len + nonce_len + hash_len)) {
+		return kr_error(EINVAL);
+	}
+
+	/* Copy client cookie data portion. */
+	memcpy(cookie, sc_input->cc, sc_input->cc_len);
+
+	if (nonce_len) {
+		/* Write nonce data portion. */
+		kr_nonce_write_wire(cookie + sc_input->cc_len, nonce_len,
+		                    nonce);
+		/* Adjust input for written nonce value. */
+		sc_input->nonce = cookie + sc_input->cc_len;
+		sc_input->nonce_len = nonce_len;
+	}
+
+	hash_len = alg->hash_func(sc_input,
+	                          cookie + sc_input->cc_len + nonce_len,
+	                          hash_len);
+	/* Zero nonce values. */
+	sc_input->nonce = NULL;
+	sc_input->nonce_len = 0;
+
+	return (hash_len != 0) ? kr_ok() : kr_error(EINVAL);
+}
+
+int kr_pkt_set_ext_rcode(knot_pkt_t *pkt, uint16_t whole_rcode)
+{
+	/*
+	 * RFC6891 6.1.3 -- extended RCODE forms the upper 8 bits of whole
+	 * 12-bit RCODE (together with the 4 bits of 'normal' RCODE).
+	 *
+	 * | 11 10 09 08 07 06 05 04 | 03 02 01 00 |
+	 * |          12-bit whole RCODE           |
+	 * |   8-bit extended RCODE  | 4-bit RCODE |
+	 */
+
+	if (!pkt || !knot_pkt_has_edns(pkt)) {
+		return kr_error(EINVAL);
+	}
+
+	uint8_t rcode = whole_rcode & 0x0f;
+	uint8_t ext_rcode = whole_rcode >> 4;
+	knot_wire_set_rcode(pkt->wire, rcode);
+	knot_edns_set_ext_rcode(pkt->opt_rr, ext_rcode);
+
+	return kr_ok();
+}
+
+uint8_t *kr_no_question_cookie_query(const knot_pkt_t *pkt)
+{
+	if (!pkt || knot_wire_get_qdcount(pkt->wire) > 0) {
+		return false;
+	}
+
+	if (knot_wire_get_qr(pkt->wire) != 0 || !pkt->opt_rr) {
+		return false;
+	}
+
+	return knot_edns_get_option(pkt->opt_rr, KNOT_EDNS_OPTION_COOKIE);
+}
+
+int kr_parse_cookie_opt(uint8_t *cookie_opt, struct knot_dns_cookies *cookies)
+{
+	if (!cookie_opt || !cookies) {
+		return kr_error(EINVAL);
+	}
+
+	const uint8_t *cookie_data = knot_edns_opt_get_data(cookie_opt);
+	uint16_t cookie_len = knot_edns_opt_get_length(cookie_opt);
+	if (!cookie_data || cookie_len == 0) {
+		return kr_error(EINVAL);
+	}
+
+	int ret =  knot_edns_opt_cookie_parse(cookie_data, cookie_len,
+	                                      &cookies->cc, &cookies->cc_len,
+	                                      &cookies->sc, &cookies->sc_len);
+
+	return (ret == KNOT_EOK) ? kr_ok() : kr_error(EINVAL);
+}
diff --git a/lib/cookies/helper.h b/lib/cookies/helper.h
new file mode 100644
index 0000000..0fee2fc
--- /dev/null
+++ b/lib/cookies/helper.h
@@ -0,0 +1,74 @@
+/*  Copyright (C) 2016-2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#pragma once
+
+#include <libknot/packet/pkt.h>
+
+#include "lib/cookies/alg_containers.h"
+#include "lib/cookies/control.h"
+#include "lib/cookies/lru_cache.h"
+#include "lib/cookies/nonce.h"
+#include "lib/defines.h"
+#include "lib/resolve.h"
+
+/**
+ * @brief Updates DNS cookie in the request EDNS options.
+ * @note This function must be called before the request packet is finalised.
+ * @param clnt_comp    client cookie control structure
+ * @param cookie_cache cookie cache
+ * @param clnt_sa      client socket address
+ * @param srvr_sa      server socket address
+ * @param req          name resolution request
+ * @return kr_ok() or error code
+ */
+KR_EXPORT
+int kr_request_put_cookie(const struct kr_cookie_comp *clnt_comp,
+                          kr_cookie_lru_t *cookie_cache,
+                          const struct sockaddr *clnt_sa,
+                          const struct sockaddr *srvr_sa,
+                          struct kr_request *req);
+
+/**
+ * @brief Inserts a cookie option into the OPT RR. It does not write any
+ *        wire data.
+ * @note The content of @a sc_input is modified. Any pre-set nonce value is
+ *       ignored. After retuning its nonce value will be null.
+ * @param sc_input  data needed to compute server cookie, nonce is ignored
+ * @param nonce     nonce value that is actually used
+ * @param alg       hash algorithm
+ * @param pkt       DNS response packet
+ */
+KR_EXPORT
+int kr_answer_write_cookie(struct knot_sc_input *sc_input,
+                           const struct kr_nonce_input *nonce,
+                           const struct knot_sc_alg *alg, knot_pkt_t *pkt);
+
+/**
+ * @brief Set RCODE and extended RCODE.
+ * @param pkt DNS packet
+ * @param whole_rcode RCODE value
+ * @return kr_ok() or error code
+ */
+KR_EXPORT
+int kr_pkt_set_ext_rcode(knot_pkt_t *pkt, uint16_t whole_rcode);
+
+/**
+ * @brief Check whether packet is a server cookie request according to
+ *        RFC7873 5.4.
+ * @param pkt Packet to be examined.
+ * @return Pointer to entire cookie option if is a server cookie query, NULL on
+ *         errors or if packet doesn't contain cookies or if QDCOUNT > 0.
+ */
+KR_EXPORT
+uint8_t *kr_no_question_cookie_query(const knot_pkt_t *pkt);
+
+/**
+ * @brief Parse cookies from cookie option.
+ * @param cookie_opt Cookie option.
+ * @param cookies    Cookie structure to be set.
+ * @return kr_ok() on success, error if cookies are malformed.
+ */
+KR_EXPORT
+int kr_parse_cookie_opt(uint8_t *cookie_opt, struct knot_dns_cookies *cookies);
diff --git a/lib/cookies/lru_cache.c b/lib/cookies/lru_cache.c
new file mode 100644
index 0000000..1b629f7
--- /dev/null
+++ b/lib/cookies/lru_cache.c
@@ -0,0 +1,58 @@
+/*  Copyright (C) 2016-2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#include <libknot/rrtype/opt.h>
+#include <string.h>
+
+#include "lib/cookies/lru_cache.h"
+#include "lib/utils.h"
+
+const uint8_t *kr_cookie_lru_get(kr_cookie_lru_t *cache,
+                                 const struct sockaddr *sa)
+{
+	if (!cache || !sa) {
+		return NULL;
+	}
+
+	int addr_len = kr_inaddr_len(sa);
+	const char *addr = kr_inaddr(sa);
+	if (!addr || addr_len <= 0) {
+		return NULL;
+	}
+
+	struct cookie_opt_data *cached = lru_get_try(cache, addr, addr_len);
+	return cached ? cached->opt_data : NULL;
+}
+
+int kr_cookie_lru_set(kr_cookie_lru_t *cache, const struct sockaddr *sa,
+                      uint8_t *opt)
+{
+	if (!cache || !sa) {
+		return kr_error(EINVAL);
+	}
+
+	if (!opt) {
+		return kr_ok();
+	}
+
+	int addr_len = kr_inaddr_len(sa);
+	const char *addr = kr_inaddr(sa);
+	if (!addr || addr_len <= 0) {
+		return kr_error(EINVAL);
+	}
+
+	uint16_t opt_size = KNOT_EDNS_OPTION_HDRLEN +
+	                    knot_edns_opt_get_length(opt);
+
+	if (opt_size > KR_COOKIE_OPT_MAX_LEN) {
+		return kr_error(EINVAL);
+	}
+
+	struct cookie_opt_data *cached = lru_get_new(cache, addr, addr_len, NULL);
+	if (cached) {
+		memcpy(cached->opt_data, opt, opt_size);
+	}
+
+	return kr_ok();
+}
diff --git a/lib/cookies/lru_cache.h b/lib/cookies/lru_cache.h
new file mode 100644
index 0000000..3594ee1
--- /dev/null
+++ b/lib/cookies/lru_cache.h
@@ -0,0 +1,57 @@
+/*  Copyright (C) 2016-2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#pragma once
+
+#include <netinet/in.h>
+#include <stdint.h>
+
+#if ENABLE_COOKIES
+#include <libknot/rrtype/opt.h>
+#include <libknot/rrtype/opt-cookie.h>
+#else
+#define KNOT_OPT_COOKIE_CLNT 8
+#define KNOT_OPT_COOKIE_SRVR_MAX 32
+#endif /* ENABLE_COOKIES */
+
+#include "lib/defines.h"
+#include "lib/generic/lru.h"
+
+/** Maximal size of a cookie option. */
+#define KR_COOKIE_OPT_MAX_LEN (KNOT_EDNS_OPTION_HDRLEN + KNOT_OPT_COOKIE_CLNT + KNOT_OPT_COOKIE_SRVR_MAX)
+
+/**
+ * Cookie option entry.
+ */
+struct cookie_opt_data {
+	uint8_t opt_data[KR_COOKIE_OPT_MAX_LEN];
+};
+
+/**
+ * DNS cookies tracking.
+ */
+typedef lru_t(struct cookie_opt_data) kr_cookie_lru_t;
+
+/**
+ * @brief Obtain LRU cache entry.
+ *
+ * @param cache cookie LRU cache
+ * @param sa socket address serving as key
+ * @return pointer to cached option or NULL if not found or error occurred
+ */
+KR_EXPORT
+const uint8_t *kr_cookie_lru_get(kr_cookie_lru_t *cache,
+                                 const struct sockaddr *sa);
+
+/**
+ * @brief Stores cookie option into LRU cache.
+ *
+ * @param cache cookie LRU cache
+ * @param sa socket address serving as key
+ * @param opt cookie option to be stored
+ * @return kr_ok() or error code
+ */
+KR_EXPORT
+int kr_cookie_lru_set(kr_cookie_lru_t *cache, const struct sockaddr *sa,
+                      uint8_t *opt);
diff --git a/lib/cookies/nonce.c b/lib/cookies/nonce.c
new file mode 100644
index 0000000..8e4b754
--- /dev/null
+++ b/lib/cookies/nonce.c
@@ -0,0 +1,22 @@
+/*  Copyright (C) 2016-2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#include <assert.h>
+
+#include "contrib/wire.h"
+#include "lib/cookies/nonce.h"
+
+uint16_t kr_nonce_write_wire(uint8_t *buf, uint16_t buf_len,
+                             const struct kr_nonce_input *input)
+{
+	if (!buf || buf_len < KR_NONCE_LEN || !input) {
+		return 0;
+	}
+
+	wire_write_u32(buf, input->rand);
+	wire_write_u32(buf + sizeof(uint32_t), input->time);
+	buf_len = 2 * sizeof(uint32_t);
+
+	return buf_len;
+}
diff --git a/lib/cookies/nonce.h b/lib/cookies/nonce.h
new file mode 100644
index 0000000..4d8460f
--- /dev/null
+++ b/lib/cookies/nonce.h
@@ -0,0 +1,31 @@
+/*  Copyright (C) 2016-2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#pragma once
+
+#include "lib/defines.h"
+
+/* RFC7873 Appendix B.2 mentions an algorithm using two values before the
+ * actual server cookie hash. */
+
+/** Nonce value length. */
+#define KR_NONCE_LEN 8
+
+/** Input data to generate nonce from. */
+struct kr_nonce_input {
+	uint32_t rand; /**< some random value */
+	uint32_t time; /**< time stamp */
+};
+
+/**
+ * @brief Writes server cookie nonce value into given buffer.
+ *
+ * @param buf     buffer to write nonce data in wire format into
+ * @param buf_len buffer size
+ * @param input   data to generate wire data from
+ * @return non-zero size of written data on success, 0 on failure
+ */
+KR_EXPORT
+uint16_t kr_nonce_write_wire(uint8_t *buf, uint16_t buf_len,
+                             const struct kr_nonce_input *input);
diff --git a/lib/defines.h b/lib/defines.h
new file mode 100644
index 0000000..dc8c378
--- /dev/null
+++ b/lib/defines.h
@@ -0,0 +1,99 @@
+/*  Copyright (C) 2014-2020 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#pragma once
+
+#include <errno.h>
+#include <libknot/errcode.h>
+#include <libknot/dname.h>
+#include <libknot/rrset.h>
+
+/* Function attributes */
+#if __GNUC__ >= 4
+#define KR_EXPORT __attribute__ ((visibility ("default")))
+#define KR_CONST __attribute__((__const__))
+#define KR_PURE __attribute__((__pure__))
+#define KR_NORETURN __attribute__((__noreturn__))
+#define KR_COLD __attribute__((__cold__))
+#define KR_PRINTF(n) __attribute__((format (printf, n, (n+1))))
+#else
+#define KR_EXPORT
+#define KR_CONST
+#define KR_PURE
+#define KR_NORETURN
+#define KR_COLD
+#define KR_PRINTF(n)
+#endif
+
+#ifndef uint /* Redefining typedef is a C11 feature. */
+typedef unsigned int uint;
+#define uint uint
+#endif
+
+/*
+ * Error codes.
+ */
+#define kr_ok() 0
+/* Mark as cold to mark all branches as unlikely. */
+static inline int KR_COLD kr_error(int x) {
+    return x <= 0 ? x : -x;
+}
+#define kr_strerror(x) strerror(abs(x))
+
+/*
+ * Connection limits.
+ * @cond internal
+ */
+#define KR_CONN_RTT_MAX 2000 /* Timeout for network activity */
+#define KR_CONN_RETRY 200    /* Retry interval for network activity */
+#define KR_ITER_LIMIT 100    /* Built-in iterator limit */
+#define KR_RESOLVE_TIME_LIMIT 10000 /* Upper limit for resolution time of single query, ms */
+#define KR_CNAME_CHAIN_LIMIT 13 /* Built-in maximum CNAME chain length */
+#define KR_TIMEOUT_LIMIT 10   /* Maximum number of retries after timeout. */
+#define KR_QUERY_NSRETRY_LIMIT 4 /* Maximum number of retries per query. */
+#define KR_COUNT_NO_NSADDR_LIMIT 5
+#define KR_CONSUME_FAIL_ROW_LIMIT 3 /* Maximum number of KR_STATE_FAIL in a row. */
+
+/*
+ * Defines.
+ */
+#define KR_DNS_PORT   53
+#define KR_DNS_DOH_PORT 443
+#define KR_DNS_TLS_PORT 853
+#define KR_EDNS_VERSION 0
+#define KR_EDNS_PAYLOAD 1232 /* Default UDP payload; see https://dnsflagday.net/2020/ */
+#define KR_CACHE_DEFAULT_TTL_MIN (5) /* avoid bursts of queries */
+#define KR_CACHE_DEFAULT_TTL_MAX (6 * 24 * 3600) /* 6 days, like the root NS TTL */
+
+#define KR_DNAME_STR_MAXLEN (KNOT_DNAME_TXT_MAXLEN + 1)
+#define KR_RRTYPE_STR_MAXLEN (16 + 1)
+
+/*
+ * Address sanitizer hints.
+ */
+#if !defined(__SANITIZE_ADDRESS__) && defined(__has_feature)
+# if __has_feature(address_sanitizer)
+#  define __SANITIZE_ADDRESS__ 1
+# endif
+#endif
+#if defined(__SANITIZE_ADDRESS__)
+void __asan_poison_memory_region(void const volatile *addr, size_t size);
+void __asan_unpoison_memory_region(void const volatile *addr, size_t size);
+#define kr_asan_poison(addr, size) __asan_poison_memory_region((addr), (size))
+#define kr_asan_unpoison(addr, size) __asan_unpoison_memory_region((addr), (size))
+#define kr_asan_custom_poison(fn, addr) fn ##_poison((addr))
+#define kr_asan_custom_unpoison(fn, addr) fn ##_unpoison((addr))
+#else
+#define kr_asan_poison(addr, size)
+#define kr_asan_unpoison(addr, size)
+#define kr_asan_custom_poison(fn, addr)
+#define kr_asan_custom_unpoison(fn, addr)
+#endif
+
+#if defined(__SANITIZE_ADDRESS__) && defined(_FORTIFY_SOURCE)
+	#error "You can't use address sanitizer with _FORTIFY_SOURCE"
+	// https://github.com/google/sanitizers/issues/247
+#endif
+
+/* @endcond */
diff --git a/lib/dnssec.c b/lib/dnssec.c
new file mode 100644
index 0000000..7490a67
--- /dev/null
+++ b/lib/dnssec.c
@@ -0,0 +1,479 @@
+/*  Copyright (C) 2015-2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#include <assert.h>
+#include <libdnssec/binary.h>
+#include <libdnssec/crypto.h>
+#include <libdnssec/error.h>
+#include <libdnssec/key.h>
+#include <libdnssec/sign.h>
+#include <libknot/descriptor.h>
+#include <libknot/packet/wire.h>
+#include <libknot/rdataset.h>
+#include <libknot/rrset.h>
+#include <libknot/rrtype/dnskey.h>
+#include <libknot/rrtype/nsec.h>
+#include <libknot/rrtype/rrsig.h>
+
+#include "contrib/cleanup.h"
+#include "contrib/wire.h"
+#include "lib/defines.h"
+#include "lib/dnssec/nsec.h"
+#include "lib/dnssec/nsec3.h"
+#include "lib/dnssec/signature.h"
+#include "lib/dnssec.h"
+#include "lib/resolve.h"
+
+/* forward */
+static int kr_rrset_validate_with_key(kr_rrset_validation_ctx_t *vctx,
+	knot_rrset_t *covered, size_t key_pos, const struct dseckey *key);
+
+void kr_crypto_init(void)
+{
+	dnssec_crypto_init();
+}
+
+void kr_crypto_cleanup(void)
+{
+	dnssec_crypto_cleanup();
+}
+
+void kr_crypto_reinit(void)
+{
+	dnssec_crypto_reinit();
+}
+
+#define FLG_WILDCARD_EXPANSION 0x01 /**< Possibly generated by using wildcard expansion. */
+
+/**
+ * Check the RRSIG RR validity according to RFC4035 5.3.1 .
+ * @param flags     The flags are going to be set according to validation result.
+ * @param cov_labels Covered RRSet owner label count.
+ * @param rrsigs    rdata containing the signatures.
+ * @param key_owner Associated DNSKEY's owner.
+ * @param key_rdata Associated DNSKEY's rdata.
+ * @param keytag    Used key tag.
+ * @param zone_name The name of the zone cut.
+ * @param timestamp Validation time.
+ */
+static int validate_rrsig_rr(int *flags, int cov_labels,
+                             const knot_rdata_t *rrsigs,
+                             const knot_dname_t *key_owner, const knot_rdata_t *key_rdata,
+			     uint16_t keytag,
+                             const knot_dname_t *zone_name, uint32_t timestamp,
+                             kr_rrset_validation_ctx_t *vctx)
+{
+	if (!flags || !rrsigs || !key_owner || !key_rdata || !zone_name) {
+		return kr_error(EINVAL);
+	}
+	/* bullet 5 */
+	if (knot_rrsig_sig_expiration(rrsigs) < timestamp) {
+		vctx->rrs_counters.expired++;
+		return kr_error(EINVAL);
+	}
+	/* bullet 6 */
+	if (knot_rrsig_sig_inception(rrsigs) > timestamp) {
+		vctx->rrs_counters.notyet++;
+		return kr_error(EINVAL);
+	}
+	/* bullet 2 */
+	const knot_dname_t *signer_name = knot_rrsig_signer_name(rrsigs);
+	if (!signer_name || !knot_dname_is_equal(signer_name, zone_name)) {
+		vctx->rrs_counters.signer_invalid++;
+		return kr_error(EAGAIN);
+	}
+	/* bullet 4 */
+	{
+		int rrsig_labels = knot_rrsig_labels(rrsigs);
+		if (rrsig_labels > cov_labels) {
+			vctx->rrs_counters.labels_invalid++;
+			return kr_error(EINVAL);
+		}
+		if (rrsig_labels < cov_labels) {
+			*flags |= FLG_WILDCARD_EXPANSION;
+		}
+	}
+
+	/* bullet 7 */
+	if ((!knot_dname_is_equal(key_owner, signer_name)) ||
+	    (knot_dnskey_alg(key_rdata) != knot_rrsig_alg(rrsigs)) ||
+	    (keytag != knot_rrsig_key_tag(rrsigs))) {
+		vctx->rrs_counters.key_invalid++;
+		return kr_error(EINVAL);
+	}
+	/* bullet 8 */
+	/* Checked somewhere else. */
+	/* bullet 9 and 10 */
+	/* One of the requirements should be always fulfilled. */
+
+	return kr_ok();
+}
+
+/**
+ * Returns the number of labels that have been added by wildcard expansion.
+ * @param expanded Expanded wildcard.
+ * @param rrsigs   RRSet containing the signatures.
+ * @param sig_pos  Specifies the signature within the RRSIG RRSet.
+ * @return         Number of added labels, -1 on error.
+ */
+static inline int wildcard_radix_len_diff(const knot_dname_t *expanded,
+					  const knot_rdata_t *rrsig)
+{
+	if (!expanded || !rrsig) {
+		return -1;
+	}
+
+	return knot_dname_labels(expanded, NULL) - knot_rrsig_labels(rrsig);
+}
+
+int kr_rrset_validate(kr_rrset_validation_ctx_t *vctx, knot_rrset_t *covered)
+{
+	if (!vctx) {
+		return kr_error(EINVAL);
+	}
+	if (!vctx->pkt || !covered || !vctx->keys || !vctx->zone_name) {
+		return kr_error(EINVAL);
+	}
+
+	memset(&vctx->rrs_counters, 0, sizeof(vctx->rrs_counters));
+	for (unsigned i = 0; i < vctx->keys->rrs.count; ++i) {
+		int ret = kr_rrset_validate_with_key(vctx, covered, i, NULL);
+		if (ret == 0) {
+			return ret;
+		}
+	}
+
+	return kr_error(ENOENT);
+}
+
+/**
+ * Validate RRSet using a specific key.
+ * @param vctx    Pointer to validation context.
+ * @param covered RRSet covered by a signature.  It must be in canonical format.
+ * 		  TTL may get lowered.
+ * @param key_pos Position of the key to be validated with.
+ * @param key     Key to be used to validate.
+ *		  If NULL, then key from DNSKEY RRSet is used.
+ * @return        0 or error code, same as vctx->result.
+ */
+static int kr_rrset_validate_with_key(kr_rrset_validation_ctx_t *vctx,
+				knot_rrset_t *covered,
+				size_t key_pos, const struct dseckey *key)
+{
+	const knot_pkt_t *pkt         = vctx->pkt;
+	const knot_rrset_t *keys      = vctx->keys;
+	const knot_dname_t *zone_name = vctx->zone_name;
+	uint32_t timestamp            = vctx->timestamp;
+	bool has_nsec3		      = vctx->has_nsec3;
+	struct dseckey *created_key = NULL;
+
+	/* It's just caller's approximation that the RR is in that particular zone.
+	 * We MUST guard against attempts of zones signing out-of-bailiwick records. */
+	if (knot_dname_in_bailiwick(covered->owner, zone_name) < 0) {
+		vctx->result = kr_error(ENOENT);
+		return vctx->result;
+	}
+
+	const knot_rdata_t *key_rdata = knot_rdataset_at(&keys->rrs, key_pos);
+	if (key == NULL) {
+		int ret = kr_dnssec_key_from_rdata(&created_key, keys->owner,
+						   key_rdata->data, key_rdata->len);
+		if (ret != 0) {
+			vctx->result = ret;
+			return vctx->result;
+		}
+		key = created_key;
+	}
+	uint16_t keytag = dnssec_key_get_keytag((dnssec_key_t *)key);
+	int covered_labels = knot_dname_labels(covered->owner, NULL);
+	if (knot_dname_is_wildcard(covered->owner)) {
+		/* The asterisk does not count, RFC4034 3.1.3, paragraph 3. */
+		--covered_labels;
+	}
+
+	for (uint16_t i = 0; i < vctx->rrs->len; ++i) {
+		/* Consider every RRSIG that matches and comes from the same query. */
+		const knot_rrset_t *rrsig = vctx->rrs->at[i]->rr;
+		const bool ok = vctx->rrs->at[i]->qry_uid == vctx->qry_uid
+			&& rrsig->type == KNOT_RRTYPE_RRSIG
+			&& rrsig->rclass == covered->rclass
+			&& knot_dname_is_equal(rrsig->owner, covered->owner);
+		if (!ok)
+			continue;
+
+		knot_rdata_t *rdata_j = rrsig->rrs.rdata;
+		for (uint16_t j = 0; j < rrsig->rrs.count; ++j, rdata_j = knot_rdataset_next(rdata_j)) {
+			int val_flgs = 0;
+			int trim_labels = 0;
+			if (knot_rrsig_type_covered(rdata_j) != covered->type) {
+				continue;
+			}
+			kr_rank_set(&vctx->rrs->at[i]->rank, KR_RANK_BOGUS); /* defensive style */
+			vctx->rrs_counters.matching_name_type++;
+			int retv = validate_rrsig_rr(&val_flgs, covered_labels, rdata_j,
+			                      keys->owner, key_rdata, keytag,
+			                      zone_name, timestamp, vctx);
+			if (retv == kr_error(EAGAIN)) {
+				kr_dnssec_key_free(&created_key);
+				vctx->result = retv;
+				return retv;
+			} else if (retv != 0) {
+				continue;
+			}
+			if (val_flgs & FLG_WILDCARD_EXPANSION) {
+				trim_labels = wildcard_radix_len_diff(covered->owner, rdata_j);
+				if (trim_labels < 0) {
+					break;
+				}
+			}
+			if (kr_check_signature(rdata_j, (dnssec_key_t *) key, covered, trim_labels) != 0) {
+				vctx->rrs_counters.crypto_invalid++;
+				continue;
+			}
+			if (val_flgs & FLG_WILDCARD_EXPANSION) {
+				int ret = 0;
+				if (!has_nsec3) {
+					ret = kr_nsec_wildcard_answer_response_check(pkt, KNOT_AUTHORITY, covered->owner);
+				} else {
+					ret = kr_nsec3_wildcard_answer_response_check(pkt, KNOT_AUTHORITY, covered->owner, trim_labels - 1);
+					if (ret == kr_error(KNOT_ERANGE)) {
+						ret = 0;
+						vctx->flags |= KR_DNSSEC_VFLG_OPTOUT;
+					}
+				}
+				if (ret != 0) {
+					vctx->rrs_counters.nsec_invalid++;
+					continue;
+				}
+				vctx->flags |= KR_DNSSEC_VFLG_WEXPAND;
+			}
+			/* Validated with current key, OK;
+			 * now just trim TTL in case it's over-extended. */
+			const uint32_t ttl_max = MIN(knot_rrsig_original_ttl(rdata_j),
+					knot_rrsig_sig_expiration(rdata_j) - timestamp);
+			if (unlikely(covered->ttl > ttl_max)) {
+				if (VERBOSE_STATUS) {
+					auto_free char
+						*name_str = kr_dname_text(covered->owner),
+						*type_str = kr_rrtype_text(covered->type);
+					QRVERBOSE(NULL, "vldr",
+						"trimming TTL of %s %s: %d -> %d\n",
+						name_str, type_str,
+						(int)covered->ttl, (int)ttl_max);
+				}
+				covered->ttl = ttl_max;
+			}
+
+			kr_dnssec_key_free(&created_key);
+			vctx->result = kr_ok();
+			kr_rank_set(&vctx->rrs->at[i]->rank, KR_RANK_SECURE); /* upgrade from bogus */
+			return vctx->result;
+		}
+	}
+	/* No applicable key found, cannot be validated. */
+	kr_dnssec_key_free(&created_key);
+	vctx->result = kr_error(ENOENT);
+	return vctx->result;
+}
+
+bool kr_ds_algo_support(const knot_rrset_t *ta)
+{
+	assert(ta && ta->type == KNOT_RRTYPE_DS && ta->rclass == KNOT_CLASS_IN);
+	/* Check if at least one DS has a usable algorithm pair. */
+	knot_rdata_t *rdata_i = ta->rrs.rdata;
+	for (uint16_t i = 0; i < ta->rrs.count;
+			++i, rdata_i = knot_rdataset_next(rdata_i)) {
+		if (dnssec_algorithm_digest_support(knot_ds_digest_type(rdata_i))
+		    && dnssec_algorithm_key_support(knot_ds_alg(rdata_i))) {
+			return true;
+		}
+	}
+	return false;
+}
+
+int kr_dnskeys_trusted(kr_rrset_validation_ctx_t *vctx, const knot_rrset_t *ta)
+{
+	const knot_pkt_t *pkt         = vctx->pkt;
+	knot_rrset_t *keys            = vctx->keys;
+
+	const bool ok = pkt && keys && ta && ta->rrs.count && ta->rrs.rdata
+			&& ta->type == KNOT_RRTYPE_DS;
+	if (!ok) {
+		assert(false);
+		return kr_error(EINVAL);
+	}
+
+	/* RFC4035 5.2, bullet 1
+	 * The supplied DS record has been authenticated.
+	 * It has been validated or is part of a configured trust anchor.
+	 */
+	memset(&vctx->rrs_counters, 0, sizeof(vctx->rrs_counters));
+	for (uint16_t i = 0; i < keys->rrs.count; ++i) {
+		/* RFC4035 5.3.1, bullet 8 */ /* ZSK */
+		/* LATER(optim.): more efficient way to iterate than _at() */
+		knot_rdata_t *krr = knot_rdataset_at(&keys->rrs, i);
+		if (!kr_dnssec_key_zsk(krr->data) || kr_dnssec_key_revoked(krr->data)) {
+			continue;
+		}
+		
+		struct dseckey *key = NULL;
+		if (kr_dnssec_key_from_rdata(&key, keys->owner, krr->data, krr->len) != 0) {
+			continue;
+		}
+		if (kr_authenticate_referral(ta, (dnssec_key_t *) key) != 0) {
+			kr_dnssec_key_free(&key);
+			continue;
+		}
+		if (kr_rrset_validate_with_key(vctx, keys, i, key) != 0) {
+			kr_dnssec_key_free(&key);
+			continue;
+		}
+		kr_dnssec_key_free(&key);
+		assert (vctx->result == 0);
+		return vctx->result;
+	}
+
+	/* No useable key found */
+	vctx->result = kr_error(ENOENT);
+	return vctx->result;
+}
+
+bool kr_dnssec_key_zsk(const uint8_t *dnskey_rdata)
+{
+	return wire_read_u16(dnskey_rdata) & 0x0100;
+}
+
+bool kr_dnssec_key_ksk(const uint8_t *dnskey_rdata)
+{
+	return wire_read_u16(dnskey_rdata) & 0x0001;
+}
+
+/** Return true if the DNSKEY is revoked. */
+bool kr_dnssec_key_revoked(const uint8_t *dnskey_rdata)
+{
+	return wire_read_u16(dnskey_rdata) & 0x0080;
+}
+
+int kr_dnssec_key_tag(uint16_t rrtype, const uint8_t *rdata, size_t rdlen)
+{
+	if (!rdata || rdlen == 0 || (rrtype != KNOT_RRTYPE_DS && rrtype != KNOT_RRTYPE_DNSKEY)) {
+		return kr_error(EINVAL);
+	}
+	if (rrtype == KNOT_RRTYPE_DS) {
+		return wire_read_u16(rdata);
+	} else if (rrtype == KNOT_RRTYPE_DNSKEY) {
+		struct dseckey *key = NULL;
+		int ret = kr_dnssec_key_from_rdata(&key, NULL, rdata, rdlen);
+		if (ret != 0) {
+			return ret;
+		}
+		uint16_t keytag = dnssec_key_get_keytag((dnssec_key_t *)key);
+		kr_dnssec_key_free(&key);
+		return keytag;
+	} else {
+		return kr_error(EINVAL);
+	}
+}
+
+int kr_dnssec_key_match(const uint8_t *key_a_rdata, size_t key_a_rdlen,
+                        const uint8_t *key_b_rdata, size_t key_b_rdlen)
+{
+	dnssec_key_t *key_a = NULL, *key_b = NULL;
+	int ret = kr_dnssec_key_from_rdata((struct dseckey **)&key_a, NULL, key_a_rdata, key_a_rdlen);
+	if (ret != 0) {
+		return ret;
+	}
+	ret = kr_dnssec_key_from_rdata((struct dseckey **)&key_b, NULL, key_b_rdata, key_b_rdlen);
+	if (ret != 0) {
+		dnssec_key_free(key_a);
+		return ret;
+	}
+	/* If the algorithm and the public key match, we can be sure
+	 * that they are the same key. */
+	ret = kr_error(ENOENT);
+	dnssec_binary_t pk_a, pk_b;
+	if (dnssec_key_get_algorithm(key_a) == dnssec_key_get_algorithm(key_b) &&
+	    dnssec_key_get_pubkey(key_a, &pk_a) == DNSSEC_EOK &&
+	    dnssec_key_get_pubkey(key_b, &pk_b) == DNSSEC_EOK) {
+		if (pk_a.size == pk_b.size && memcmp(pk_a.data, pk_b.data, pk_a.size) == 0) {
+			ret = 0;
+		}
+	}
+	dnssec_key_free(key_a);
+	dnssec_key_free(key_b);
+	return ret;
+}
+
+int kr_dnssec_key_from_rdata(struct dseckey **key, const knot_dname_t *kown, const uint8_t *rdata, size_t rdlen)
+{
+	if (!key || !rdata || rdlen == 0) {
+		return kr_error(EINVAL);
+	}
+
+	dnssec_key_t *new_key = NULL;
+	const dnssec_binary_t binary_key = {
+		.size = rdlen,
+		.data = (uint8_t *)rdata
+	};
+
+	int ret = dnssec_key_new(&new_key);
+	if (ret != DNSSEC_EOK) {
+		return kr_error(ENOMEM);
+	}
+	ret = dnssec_key_set_rdata(new_key, &binary_key);
+	if (ret != DNSSEC_EOK) {
+		dnssec_key_free(new_key);
+		return kr_error(ret);
+	}
+	if (kown) {
+		ret = dnssec_key_set_dname(new_key, kown);
+		if (ret != DNSSEC_EOK) {
+			dnssec_key_free(new_key);
+			return kr_error(ENOMEM);
+		}
+	}
+
+	*key = (struct dseckey *) new_key;
+	return kr_ok();
+}
+
+void kr_dnssec_key_free(struct dseckey **key)
+{
+	assert(key);
+
+	dnssec_key_free((dnssec_key_t *) *key);
+	*key = NULL;
+}
+
+int kr_dnssec_matches_name_and_type(const ranked_rr_array_t *rrs, uint32_t qry_uid,
+				    const knot_dname_t *name, uint16_t type)
+{
+	int ret = kr_error(ENOENT);
+	for (size_t i = 0; i < rrs->len; ++i) {
+		const ranked_rr_array_entry_t *entry = rrs->at[i];
+		assert(!entry->in_progress);
+		const knot_rrset_t *nsec = entry->rr;
+		if (entry->qry_uid != qry_uid || entry->yielded) {
+			continue;
+		}
+		if (nsec->type != KNOT_RRTYPE_NSEC &&
+		    nsec->type != KNOT_RRTYPE_NSEC3) {
+			continue;
+		}
+		if (!kr_rank_test(entry->rank, KR_RANK_SECURE)) {
+			continue;
+		}
+		if (nsec->type == KNOT_RRTYPE_NSEC) {
+			ret = kr_nsec_matches_name_and_type(nsec, name, type);
+		} else {
+			ret = kr_nsec3_matches_name_and_type(nsec, name, type);
+		}
+		if (ret == kr_ok()) {
+			return kr_ok();
+		} else if (ret != kr_error(ENOENT)) {
+			return ret;
+		}
+	}
+	return ret;
+}
diff --git a/lib/dnssec.h b/lib/dnssec.h
new file mode 100644
index 0000000..d9601ea
--- /dev/null
+++ b/lib/dnssec.h
@@ -0,0 +1,145 @@
+/*  Copyright (C) 2015-2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#pragma once
+
+#include "lib/defines.h"
+#include "lib/utils.h"
+#include <libknot/packet/pkt.h>
+
+/**
+ * Initialise cryptographic back-end.
+ */
+KR_EXPORT
+void kr_crypto_init(void);
+
+/**
+ * De-initialise cryptographic back-end.
+ */
+KR_EXPORT
+void kr_crypto_cleanup(void);
+
+/**
+ * Re-initialise cryptographic back-end.
+ * @note Must be called after fork() in the child.
+ */
+KR_EXPORT
+void kr_crypto_reinit(void);
+
+/** Opaque DNSSEC key pointer. */
+struct dseckey;
+
+#define KR_DNSSEC_VFLG_WEXPAND 0x01
+#define KR_DNSSEC_VFLG_OPTOUT  0x02
+
+/** DNSSEC validation context. */
+struct kr_rrset_validation_ctx {
+	const knot_pkt_t *pkt;		/*!< Packet to be validated. */
+	ranked_rr_array_t *rrs;		/*!< List of preselected RRs to be validated. */
+	knot_section_t section_id;	/*!< Section to work with. */
+	knot_rrset_t *keys;		/*!< DNSKEY RRSet; TTLs may get lowered when validating this set. */
+        const knot_dname_t *zone_name;	/*!< Name of the zone containing the RRSIG RRSet. */
+	uint32_t timestamp;		/*!< Validation time. */
+        bool has_nsec3;			/*!< Whether to use NSEC3 validation. */
+	uint32_t qry_uid;		/*!< Current query uid. */
+	uint32_t flags;			/*!< Output - Flags. */
+	uint32_t err_cnt;		/*!< Output - Number of validation failures. */
+	uint32_t cname_norrsig_cnt;	/*!< Output - Number of CNAMEs missing RRSIGs. */
+	int result;			/*!< Output - 0 or error code. */
+	struct {
+		unsigned int matching_name_type;	/*!< Name + type matches */
+		unsigned int expired;
+		unsigned int notyet;
+		unsigned int signer_invalid;		/*!< Signer is not zone apex */
+		unsigned int labels_invalid;		/*!< Number of labels in RRSIG */
+		unsigned int key_invalid;		/*!< Algorithm/keytag/key owner */
+		unsigned int crypto_invalid;
+		unsigned int nsec_invalid;
+	} rrs_counters;	/*!< Error counters for single RRset validation. */
+};
+
+typedef struct kr_rrset_validation_ctx kr_rrset_validation_ctx_t;
+
+/**
+ * Validate RRSet.
+ * @param vctx    Pointer to validation context.
+ * @param covered RRSet covered by a signature. It must be in canonical format.
+ * 		  Its TTL may get lowered.
+ * @return        0 or error code, same as vctx->result.
+ */
+int kr_rrset_validate(kr_rrset_validation_ctx_t *vctx, knot_rrset_t *covered);
+
+/**
+ * Return true iff the RRset contains at least one usable DS.  See RFC6840 5.2.
+ */
+KR_EXPORT KR_PURE
+bool kr_ds_algo_support(const knot_rrset_t *ta);
+
+/**
+ * Check whether the DNSKEY rrset matches the supplied trust anchor RRSet.
+ * @param vctx  Pointer to validation context.  Note that TTL of vctx->keys may get lowered.
+ * @param ta    Trust anchor RRSet against which to validate the DNSKEY RRSet.
+ * @return      0 or error code, same as vctx->result.
+ */
+int kr_dnskeys_trusted(kr_rrset_validation_ctx_t *vctx, const knot_rrset_t *ta);
+
+/** Return true if the DNSKEY can be used as a ZSK.  */
+KR_EXPORT KR_PURE
+bool kr_dnssec_key_zsk(const uint8_t *dnskey_rdata);
+
+/** Return true if the DNSKEY indicates being KSK (=> has SEP).  */
+KR_EXPORT KR_PURE
+bool kr_dnssec_key_ksk(const uint8_t *dnskey_rdata);
+
+/** Return true if the DNSKEY is revoked. */
+KR_EXPORT KR_PURE
+bool kr_dnssec_key_revoked(const uint8_t *dnskey_rdata);
+
+/** Return DNSKEY tag.
+  * @param rrtype RR type (either DS or DNSKEY are supported)
+  * @param rdata  Key/digest RDATA.
+  * @param rdlen  RDATA length.
+  * @return Key tag (positive number), or an error code
+  */
+KR_EXPORT KR_PURE
+int kr_dnssec_key_tag(uint16_t rrtype, const uint8_t *rdata, size_t rdlen);
+
+/** Return 0 if the two keys are identical.
+  * @note This compares RDATA only, algorithm and public key must match.
+  * @param key_a_rdata First key RDATA
+  * @param key_a_rdlen First key RDATA length
+  * @param key_b_rdata Second key RDATA
+  * @param key_b_rdlen Second key RDATA length
+  * @return 0 if they match or an error code
+  */
+KR_EXPORT KR_PURE
+int kr_dnssec_key_match(const uint8_t *key_a_rdata, size_t key_a_rdlen,
+                        const uint8_t *key_b_rdata, size_t key_b_rdlen);
+
+/**
+ * Construct a DNSSEC key.
+ * @param key   Pointer to be set to newly created DNSSEC key.
+ * @param kown  DNSKEY owner name.
+ * @param rdata DNSKEY RDATA
+ * @param rdlen DNSKEY RDATA length
+ * @return 0 or error code; in particular: DNSSEC_INVALID_KEY_ALGORITHM
+ */
+int kr_dnssec_key_from_rdata(struct dseckey **key, const knot_dname_t *kown, const uint8_t *rdata, size_t rdlen);
+
+/**
+ * Frees the DNSSEC key.
+ * @param key Pointer to freed key.
+ */
+void kr_dnssec_key_free(struct dseckey **key);
+
+/**
+ * Checks whether NSEC/NSEC3 RR selected by iterator matches the supplied name and type.
+ * @param rrs     Records selected by iterator.
+ * @param qry_uid Query unique identifier where NSEC/NSEC3 belongs to.
+ * @param name    Name to be checked.
+ * @param type    Type to be checked.
+ * @return        0 or error code.
+ */
+int kr_dnssec_matches_name_and_type(const ranked_rr_array_t *rrs, uint32_t qry_uid,
+				    const knot_dname_t *name, uint16_t type);
diff --git a/lib/dnssec/nsec.c b/lib/dnssec/nsec.c
new file mode 100644
index 0000000..caab245
--- /dev/null
+++ b/lib/dnssec/nsec.c
@@ -0,0 +1,528 @@
+/*  Copyright (C) 2015-2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#include <assert.h>
+#include <stdlib.h>
+
+#include <libknot/descriptor.h>
+#include <libknot/dname.h>
+#include <libknot/packet/wire.h>
+#include <libknot/rrset.h>
+#include <libknot/rrtype/nsec.h>
+#include <libknot/rrtype/rrsig.h>
+#include <libdnssec/error.h>
+#include <libdnssec/nsec.h>
+
+#include "lib/defines.h"
+#include "lib/dnssec/nsec.h"
+
+
+int kr_nsec_children_in_zone_check(const uint8_t *bm, uint16_t bm_size)
+{
+	if (!bm) {
+		return kr_error(EINVAL);
+	}
+	const bool parent_side =
+		dnssec_nsec_bitmap_contains(bm, bm_size, KNOT_RRTYPE_DNAME)
+		|| (dnssec_nsec_bitmap_contains(bm, bm_size, KNOT_RRTYPE_NS)
+		    && !dnssec_nsec_bitmap_contains(bm, bm_size, KNOT_RRTYPE_SOA)
+		);
+	return parent_side ? abs(ENOENT) : kr_ok();
+	/* LATER: after refactoring, probably also check if signer name equals owner,
+	 * but even without that it's not possible to attack *correctly* signed zones.
+	 */
+}
+
+/**
+ * Check whether the NSEC RR proves that there is no closer match for <SNAME, SCLASS>.
+ * @param nsec  NSEC RRSet.
+ * @param sname Searched name.
+ * @return      0 if proves, >0 if not (abs(ENOENT)), or error code (<0).
+ */
+static int nsec_covers(const knot_rrset_t *nsec, const knot_dname_t *sname)
+{
+	assert(nsec && sname);
+	if (knot_dname_cmp(sname, nsec->owner) <= 0) {
+		return abs(ENOENT); /* 'sname' before 'owner', so can't be covered */
+	}
+
+	/* If NSEC 'owner' >= 'next', it means that there is nothing after 'owner' */
+	/* We have to lower-case it with libknot >= 2.7; see also RFC 6840 5.1. */
+	knot_dname_t next[KNOT_DNAME_MAXLEN];
+	int ret = knot_dname_to_wire(next, knot_nsec_next(nsec->rrs.rdata), sizeof(next));
+	if (ret < 0) {
+		assert(!ret);
+		return kr_error(ret);
+	}
+	knot_dname_to_lower(next);
+
+	const bool is_last_nsec = knot_dname_cmp(nsec->owner, next) >= 0;
+	const bool in_range = is_last_nsec || knot_dname_cmp(sname, next) < 0;
+	if (!in_range) {
+		return abs(ENOENT);
+	}
+	/* Before returning kr_ok(), we have to check a special case:
+	 * sname might be under delegation from owner and thus
+	 * not in the zone of this NSEC at all.
+	 */
+	if (knot_dname_in_bailiwick(sname, nsec->owner) <= 0) {
+		return kr_ok();
+	}
+	const uint8_t *bm = knot_nsec_bitmap(nsec->rrs.rdata);
+	uint16_t bm_size = knot_nsec_bitmap_len(nsec->rrs.rdata);
+
+	return kr_nsec_children_in_zone_check(bm, bm_size);
+}
+
+#define FLG_NOEXIST_RRTYPE (1 << 0) /**< <SNAME, SCLASS> exists, <SNAME, SCLASS, STYPE> does not exist. */
+#define FLG_NOEXIST_RRSET  (1 << 1) /**< <SNAME, SCLASS> does not exist. */
+#define FLG_NOEXIST_WILDCARD (1 << 2) /**< No wildcard covering <SNAME, SCLASS> exists. */
+#define FLG_NOEXIST_CLOSER (1 << 3) /**< Wildcard covering <SNAME, SCLASS> exists, but doesn't match STYPE. */
+
+
+/**
+ * According to set flags determine whether NSEC proving
+ * RRset or RRType non-existense has been found.
+ * @param f Flags to inspect.
+ * @return  True if required NSEC exists.
+ */
+#define kr_nsec_rrset_noexist(f) \
+        ((f) & (FLG_NOEXIST_RRTYPE | FLG_NOEXIST_RRSET))
+/**
+ * According to set flags determine whether wildcard non-existense
+ * has been proven.
+ * @param f Flags to inspect.
+ * @return  True if wildcard not exists.
+ */
+#define kr_nsec_wcard_noexist(f) ((f) & FLG_NOEXIST_WILDCARD)
+
+/**
+ * According to set flags determine whether authenticated denial of existence has been proven.
+ * @param f Flags to inspect.
+ * @return  True if denial of existence proven.
+ */
+#define kr_nsec_existence_denied(f) \
+	((kr_nsec_rrset_noexist(f)) && (kr_nsec_wcard_noexist(f)))
+
+/**
+ * Name error response check (RFC4035 3.1.3.2; RFC4035 5.4, bullet 2).
+ * @note Returned flags must be checked in order to prove denial.
+ * @param flags Flags to be set according to check outcome.
+ * @param nsec  NSEC RR.
+ * @param name  Name to be checked.
+ * @param pool
+ * @return      0 or error code.
+ */
+static int name_error_response_check_rr(int *flags, const knot_rrset_t *nsec,
+                                        const knot_dname_t *name)
+{
+	assert(flags && nsec && name);
+
+	if (nsec_covers(nsec, name) == 0) {
+		*flags |= FLG_NOEXIST_RRSET;
+	}
+
+	/* Try to find parent wildcard that is proved by this NSEC. */ 
+	uint8_t namebuf[KNOT_DNAME_MAXLEN];
+	int ret = knot_dname_to_wire(namebuf, name, sizeof(namebuf));
+	if (ret < 0)
+		return ret;
+	knot_dname_t *ptr = namebuf;
+	while (ptr[0]) {
+		/* Remove leftmost label and replace it with '\1*'. */
+		ptr = (uint8_t *) knot_wire_next_label(ptr, NULL);
+		if (!ptr) {
+			return kr_error(EINVAL);
+		}
+		*(--ptr) = '*';
+		*(--ptr) = 1;
+		/* True if this wildcard provably doesn't exist. */
+		if (nsec_covers(nsec, ptr) == 0) {
+			*flags |= FLG_NOEXIST_WILDCARD;
+			break;
+		}
+		/* Remove added leftmost asterisk. */
+		ptr += 2;
+	}
+
+	return kr_ok();
+}
+
+int kr_nsec_name_error_response_check(const knot_pkt_t *pkt, knot_section_t section_id,
+                                      const knot_dname_t *sname)
+{
+	const knot_pktsection_t *sec = knot_pkt_section(pkt, section_id);
+	if (!sec || !sname) {
+		return kr_error(EINVAL);
+	}
+
+	int flags = 0;
+	for (unsigned i = 0; i < sec->count; ++i) {
+		const knot_rrset_t *rrset = knot_pkt_rr(sec, i);
+		if (rrset->type != KNOT_RRTYPE_NSEC) {
+			continue;
+		}
+		int ret = name_error_response_check_rr(&flags, rrset, sname);
+		if (ret != 0) {
+			return ret;
+		}
+	}
+
+	return kr_nsec_existence_denied(flags) ? kr_ok() : kr_error(ENOENT);
+}
+
+/**
+ * Returns the labels from the covering RRSIG RRs.
+ * @note The number must be the same in all covering RRSIGs.
+ * @param nsec NSEC RR.
+ * @param sec  Packet section.
+ * @param      Number of labels or (negative) error code.
+ */
+static int coverign_rrsig_labels(const knot_rrset_t *nsec, const knot_pktsection_t *sec)
+{
+	assert(nsec && sec);
+
+	int ret = kr_error(ENOENT);
+
+	for (unsigned i = 0; i < sec->count; ++i) {
+		const knot_rrset_t *rrset = knot_pkt_rr(sec, i);
+		if ((rrset->type != KNOT_RRTYPE_RRSIG) ||
+		    (!knot_dname_is_equal(rrset->owner, nsec->owner))) {
+			continue;
+		}
+
+		knot_rdata_t *rdata_j = rrset->rrs.rdata;
+		for (uint16_t j = 0; j < rrset->rrs.count;
+				++j, rdata_j = knot_rdataset_next(rdata_j)) {
+			if (knot_rrsig_type_covered(rdata_j) != KNOT_RRTYPE_NSEC) {
+				continue;
+			}
+
+			if (ret < 0) {
+				ret = knot_rrsig_labels(rdata_j);
+			} else {
+				if (ret != knot_rrsig_labels(rdata_j)) {
+					return kr_error(EINVAL);
+				}
+			}
+		}
+	}
+
+	return ret;
+}
+
+
+int kr_nsec_bitmap_nodata_check(const uint8_t *bm, uint16_t bm_size, uint16_t type, const knot_dname_t *owner)
+{
+	const int NO_PROOF = abs(ENOENT);
+	if (!bm || !owner) {
+		return kr_error(EINVAL);
+	}
+	if (dnssec_nsec_bitmap_contains(bm, bm_size, type)) {
+		return NO_PROOF;
+	}
+
+	if (type != KNOT_RRTYPE_CNAME
+	    && dnssec_nsec_bitmap_contains(bm, bm_size, KNOT_RRTYPE_CNAME)) {
+		return NO_PROOF;
+	}
+	/* Special behavior around zone cuts. */
+	switch (type) {
+	case KNOT_RRTYPE_DS:
+		/* Security feature: in case of DS also check for SOA
+		 * non-existence to be more certain that we don't hold
+		 * a child-side NSEC by some mistake (e.g. when forwarding).
+		 * See RFC4035 5.2, next-to-last paragraph.
+		 * This doesn't apply for root DS as it doesn't exist in DNS hierarchy.
+		 */
+		if (owner[0] != '\0' && dnssec_nsec_bitmap_contains(bm, bm_size, KNOT_RRTYPE_SOA)) {
+			return NO_PROOF;
+		}
+		break;
+	case KNOT_RRTYPE_CNAME:
+		/* Exception from the `default` rule.  It's perhaps disputable,
+		 * but existence of CNAME at zone apex is not allowed, so we
+		 * consider a parent-side record to be enough to prove non-existence. */
+		break;
+	default:
+		/* Parent-side delegation record isn't authoritative for non-DS;
+		 * see RFC6840 4.1. */
+		if (dnssec_nsec_bitmap_contains(bm, bm_size, KNOT_RRTYPE_NS)
+		    && !dnssec_nsec_bitmap_contains(bm, bm_size, KNOT_RRTYPE_SOA)) {
+			return NO_PROOF;
+		}
+		/* LATER(opt): perhaps short-circuit test if we repeat it here. */
+	}
+
+	return kr_ok();
+}
+
+/**
+ * Attempt to prove NODATA given a matching NSEC.
+ * @param flags Flags to be set according to check outcome.
+ * @param nsec  NSEC RR.
+ * @param type  Type to be checked.
+ * @return      0 on success, abs(ENOENT) for no proof, or error code (<0).
+ * @note        It's not a *full* proof, of course (wildcards, etc.)
+ * @TODO returning result via `flags` is just ugly.
+ */
+static int no_data_response_check_rrtype(int *flags, const knot_rrset_t *nsec,
+                                         uint16_t type)
+{
+	assert(flags && nsec);
+
+	const uint8_t *bm = knot_nsec_bitmap(nsec->rrs.rdata);
+	uint16_t bm_size = knot_nsec_bitmap_len(nsec->rrs.rdata);
+	int ret = kr_nsec_bitmap_nodata_check(bm, bm_size, type, nsec->owner);
+	if (ret == kr_ok()) {
+		*flags |= FLG_NOEXIST_RRTYPE;
+	}
+	return ret <= 0 ? ret : kr_ok();
+}
+
+/**
+ * Perform check for RR type wildcard existence denial according to RFC4035 5.4, bullet 1.
+ * @param flags Flags to be set according to check outcome.
+ * @param nsec  NSEC RR.
+ * @param sec   Packet section to work with.
+ * @return      0 or error code.
+ */
+static int no_data_wildcard_existence_check(int *flags, const knot_rrset_t *nsec,
+                                            const knot_pktsection_t *sec)
+{
+	assert(flags && nsec && sec);
+
+	int rrsig_labels = coverign_rrsig_labels(nsec, sec);
+	if (rrsig_labels < 0) {
+		return rrsig_labels;
+	}
+	int nsec_labels = knot_dname_labels(nsec->owner, NULL);
+	if (nsec_labels < 0) {
+		return nsec_labels;
+	}
+
+	if (rrsig_labels == nsec_labels) {
+		*flags |= FLG_NOEXIST_WILDCARD;
+	}
+
+	return kr_ok();
+}
+
+/**
+ * Perform check for NSEC wildcard existence that covers sname and
+ * have no stype bit set.
+ * @param pkt   Packet structure to be processed.
+ * @param sec   Packet section to work with.
+ * @param sname Queried domain name.
+ * @param stype Queried type.
+ * @return      0 or error code.
+ */
+static int wildcard_match_check(const knot_pkt_t *pkt, const knot_pktsection_t *sec,
+				const knot_dname_t *sname, uint16_t stype)
+{
+	if (!sec || !sname) {
+		return kr_error(EINVAL);
+	}
+
+	int flags = 0;
+	for (unsigned i = 0; i < sec->count; ++i) {
+		const knot_rrset_t *rrset = knot_pkt_rr(sec, i);
+		if (rrset->type != KNOT_RRTYPE_NSEC) {
+			continue;
+		}
+		if (!knot_dname_is_wildcard(rrset->owner)) {
+			continue;
+		}
+		if (!knot_dname_is_equal(rrset->owner, sname)) {
+			int wcard_labels = knot_dname_labels(rrset->owner, NULL);
+			int common_labels = knot_dname_matched_labels(rrset->owner, sname);
+			int rrsig_labels = coverign_rrsig_labels(rrset, sec);
+			if (wcard_labels < 1 ||
+			    common_labels != wcard_labels - 1 ||
+			    common_labels != rrsig_labels) {
+				continue;
+			}
+		}
+		int ret = no_data_response_check_rrtype(&flags, rrset, stype);
+		if (ret != 0) {
+			return ret;
+		}
+	}
+	return (flags & FLG_NOEXIST_RRTYPE) ? kr_ok() : kr_error(ENOENT);
+}
+
+int kr_nsec_no_data_response_check(const knot_pkt_t *pkt, knot_section_t section_id,
+                                   const knot_dname_t *sname, uint16_t stype)
+{
+	const knot_pktsection_t *sec = knot_pkt_section(pkt, section_id);
+	if (!sec || !sname) {
+		return kr_error(EINVAL);
+	}
+
+	int flags = 0;
+	for (unsigned i = 0; i < sec->count; ++i) {
+		const knot_rrset_t *rrset = knot_pkt_rr(sec, i);
+		if (rrset->type != KNOT_RRTYPE_NSEC) {
+			continue;
+		}
+		if (knot_dname_is_equal(rrset->owner, sname)) {
+			int ret = no_data_response_check_rrtype(&flags, rrset, stype);
+			if (ret != 0) {
+				return ret;
+			}
+		}
+	}
+
+	return (flags & FLG_NOEXIST_RRTYPE) ? kr_ok() : kr_error(ENOENT);
+}
+
+int kr_nsec_wildcard_answer_response_check(const knot_pkt_t *pkt, knot_section_t section_id,
+                                           const knot_dname_t *sname)
+{
+	const knot_pktsection_t *sec = knot_pkt_section(pkt, section_id);
+	if (!sec || !sname) {
+		return kr_error(EINVAL);
+	}
+
+	for (unsigned i = 0; i < sec->count; ++i) {
+		const knot_rrset_t *rrset = knot_pkt_rr(sec, i);
+		if (rrset->type != KNOT_RRTYPE_NSEC) {
+			continue;
+		}
+		if (nsec_covers(rrset, sname) == 0) {
+			return kr_ok();
+		}
+	}
+
+	return kr_error(ENOENT);
+}
+
+int kr_nsec_existence_denial(const knot_pkt_t *pkt, knot_section_t section_id,
+                             const knot_dname_t *sname, uint16_t stype)
+{
+	const knot_pktsection_t *sec = knot_pkt_section(pkt, section_id);
+	if (!sec || !sname) {
+		return kr_error(EINVAL);
+	}
+
+	int flags = 0;
+	for (unsigned i = 0; i < sec->count; ++i) {
+		const knot_rrset_t *rrset = knot_pkt_rr(sec, i);
+		if (rrset->type != KNOT_RRTYPE_NSEC) {
+			continue;
+		}
+		/* NSEC proves that name exists, but has no data (RFC4035 4.9, 1) */
+		if (knot_dname_is_equal(rrset->owner, sname)) {
+			no_data_response_check_rrtype(&flags, rrset, stype);
+		} else {
+			/* NSEC proves that name doesn't exist (RFC4035, 4.9, 2) */
+			name_error_response_check_rr(&flags, rrset, sname);
+		}
+		no_data_wildcard_existence_check(&flags, rrset, sec);
+	}
+	if (kr_nsec_existence_denied(flags)) {
+		/* denial of existence proved accordignly to 4035 5.4 -
+		 * NSEC proving either rrset non-existance or
+		 * qtype non-existance has been found,
+		 * and no wildcard expansion occurred.
+		 */
+		return kr_ok();
+	} else if (kr_nsec_rrset_noexist(flags)) {
+		/* NSEC proving either rrset non-existance or
+		 * qtype non-existance has been found,
+		 * but wildcard expansion occurs.
+		 * Try to find matching wildcard and check
+		 * corresponding types.
+		 */
+		return wildcard_match_check(pkt, sec, sname, stype);
+	}
+	return kr_error(ENOENT);
+}
+
+int kr_nsec_ref_to_unsigned(const knot_pkt_t *pkt)
+{
+	int nsec_found = 0;
+	const knot_pktsection_t *sec = knot_pkt_section(pkt, KNOT_AUTHORITY);
+	if (!sec) {
+		return kr_error(EINVAL);
+	}
+	for (unsigned i = 0; i < sec->count; ++i) {
+		const knot_rrset_t *ns = knot_pkt_rr(sec, i);
+		if (ns->type == KNOT_RRTYPE_DS) {
+			return kr_error(EEXIST);
+		}
+		if (ns->type != KNOT_RRTYPE_NS) {
+			continue;
+		}
+		nsec_found = 0;
+		for (unsigned j = 0; j < sec->count; ++j) {
+			const knot_rrset_t *nsec = knot_pkt_rr(sec, j);
+			if (nsec->type == KNOT_RRTYPE_DS) {
+				return kr_error(EEXIST);
+			}
+			if (nsec->type != KNOT_RRTYPE_NSEC) {
+				continue;
+			}
+			/* nsec found
+			 * check if owner name matches the delegation name
+			 */
+			if (!knot_dname_is_equal(nsec->owner, ns->owner)) {
+				/* nsec does not match the delegation */
+				continue;
+			}
+			nsec_found = 1;
+			const uint8_t *bm = knot_nsec_bitmap(nsec->rrs.rdata);
+			uint16_t bm_size = knot_nsec_bitmap_len(nsec->rrs.rdata);
+			if (!bm) {
+				return kr_error(EINVAL);
+			}
+			if (dnssec_nsec_bitmap_contains(bm, bm_size,
+							  KNOT_RRTYPE_NS) &&
+			    !dnssec_nsec_bitmap_contains(bm, bm_size,
+							  KNOT_RRTYPE_DS) &&
+			    !dnssec_nsec_bitmap_contains(bm, bm_size,
+							  KNOT_RRTYPE_SOA)) {
+				/* rfc4035, 5.2 */
+				return kr_ok();
+			}
+		}
+		if (nsec_found) {
+			/* nsec which owner matches
+			 * the delegation name was found,
+			 * but nsec type bitmap contains wrong types
+			 */
+			return kr_error(EINVAL);
+		} else {
+			/* nsec that matches delegation was not found */
+			return kr_error(DNSSEC_NOT_FOUND);
+		}
+	}
+
+	return kr_error(EINVAL);
+}
+
+int kr_nsec_matches_name_and_type(const knot_rrset_t *nsec,
+				   const knot_dname_t *name, uint16_t type)
+{
+	/* It's not secure enough to just check a single bit for (some) other types,
+	 * but we don't (currently) only use this API for NS.  See RFC 6840 sec. 4.
+	 */
+	if (type != KNOT_RRTYPE_NS || !nsec || !name) {
+		assert(!EINVAL);
+		return kr_error(EINVAL);
+	}
+	if (!knot_dname_is_equal(nsec->owner, name)) {
+		return kr_error(ENOENT);
+	}
+	const uint8_t *bm = knot_nsec_bitmap(nsec->rrs.rdata);
+	uint16_t bm_size = knot_nsec_bitmap_len(nsec->rrs.rdata);
+	if (!bm) {
+		return kr_error(EINVAL);
+	}
+	if (dnssec_nsec_bitmap_contains(bm, bm_size, type)) {
+		return kr_ok();
+	} else {
+		return kr_error(ENOENT);
+	}
+}
diff --git a/lib/dnssec/nsec.h b/lib/dnssec/nsec.h
new file mode 100644
index 0000000..1a2a092
--- /dev/null
+++ b/lib/dnssec/nsec.h
@@ -0,0 +1,93 @@
+/*  Copyright (C) 2015-2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#pragma once
+
+#include <libknot/packet/pkt.h>
+
+/**
+ * Check bitmap that child names are contained in the same zone.
+ * @note see RFC6840 4.1.
+ * @param bm      Bitmap from NSEC or NSEC3.
+ * @param bm_size Bitmap size.
+ * @return 0 if they are, >0 if not (abs(ENOENT)), <0 on error.
+ */
+int kr_nsec_children_in_zone_check(const uint8_t *bm, uint16_t bm_size);
+
+/**
+ * Check an NSEC or NSEC3 bitmap for NODATA for a type.
+ * @param bm      Bitmap.
+ * @param bm_size Bitmap size.
+ * @param type    RR type to check.
+ * @param owner   NSEC record owner.
+ * @note This includes special checks for zone cuts, e.g. from RFC 6840 sec. 4.
+ * @return 0, abs(ENOENT) (no proof), kr_error(EINVAL)
+ */
+int kr_nsec_bitmap_nodata_check(const uint8_t *bm, uint16_t bm_size, uint16_t type, const knot_dname_t *owner);
+
+/**
+ * Name error response check (RFC4035 3.1.3.2; RFC4035 5.4, bullet 2).
+ * @note No RRSIGs are validated.
+ * @param pkt        Packet structure to be processed.
+ * @param section_id Packet section to be processed.
+ * @param sname      Name to be checked.
+ * @return           0 or error code.
+ */
+int kr_nsec_name_error_response_check(const knot_pkt_t *pkt, knot_section_t section_id,
+                                      const knot_dname_t *sname);
+
+/**
+ * No data response check (RFC4035 3.1.3.1; RFC4035 5.4, bullet 1).
+ * @param pkt        Packet structure to be processed.
+ * @param section_id Packet section to be processed.
+ * @param sname      Name to be checked.
+ * @param stype      Type to be checked.
+ * @return           0 or error code.
+ */
+int kr_nsec_no_data_response_check(const knot_pkt_t *pkt, knot_section_t section_id,
+                                   const knot_dname_t *sname, uint16_t stype);
+
+/**
+ * Wildcard answer response check (RFC4035 3.1.3.3).
+ * @param pkt        Packet structure to be processed.
+ * @param section_id Packet section to be processed.
+ * @param sname      Name to be checked.
+ * @return           0 or error code.
+ */
+int kr_nsec_wildcard_answer_response_check(const knot_pkt_t *pkt, knot_section_t section_id,
+                                           const knot_dname_t *sname);
+
+/**
+ * Authenticated denial of existence according to RFC4035 5.4.
+ * @note No RRSIGs are validated.
+ * @param pkt        Packet structure to be processed.
+ * @param section_id Packet section to be processed.
+ * @param sname      Queried domain name.
+ * @param stype      Queried type.
+ * @return           0 or error code.
+ */
+int kr_nsec_existence_denial(const knot_pkt_t *pkt, knot_section_t section_id,
+                             const knot_dname_t *sname, uint16_t stype);
+
+/**
+ * Referral to unsigned subzone check (RFC4035 5.2).
+ * @note 	     No RRSIGs are validated.
+ * @param pkt        Packet structure to be processed.
+ * @return           0 or error code:
+ * 		     DNSSEC_NOT_FOUND - neither ds nor nsec records
+ *		     were not found.
+ *		     EEXIST - ds record was found.
+ *		     EINVAL - bogus.
+ */
+int kr_nsec_ref_to_unsigned(const knot_pkt_t *pkt);
+
+/**
+ * Checks whether supplied NSEC RR matches the supplied name and type.
+ * @param nsec  NSEC RR.
+ * @param name  Name to be checked.
+ * @param type  Type to be checked.  Only use with NS!  TODO (+copy&paste NSEC3)
+ * @return      0 or error code.
+ */
+int kr_nsec_matches_name_and_type(const knot_rrset_t *nsec,
+				   const knot_dname_t *name, uint16_t type);
diff --git a/lib/dnssec/nsec3.c b/lib/dnssec/nsec3.c
new file mode 100644
index 0000000..e9e536a
--- /dev/null
+++ b/lib/dnssec/nsec3.c
@@ -0,0 +1,768 @@
+/*  Copyright (C) 2015-2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#include <assert.h>
+#include <string.h>
+
+#include <libdnssec/binary.h>
+#include <libdnssec/error.h>
+#include <libdnssec/nsec.h>
+#include <libknot/descriptor.h>
+#include <contrib/base32hex.h>
+#include <libknot/rrset.h>
+#include <libknot/rrtype/nsec3.h>
+
+#include "lib/defines.h"
+#include "lib/dnssec/nsec.h"
+#include "lib/dnssec/nsec3.h"
+
+#define OPT_OUT_BIT 0x01
+
+//#define FLG_CLOSEST_ENCLOSER (1 << 0)
+#define FLG_CLOSEST_PROVABLE_ENCLOSER (1 << 1)
+#define FLG_NAME_COVERED (1 << 2)
+#define FLG_NAME_MATCHED (1 << 3)
+#define FLG_TYPE_BIT_MISSING (1 << 4)
+#define FLG_CNAME_BIT_MISSING (1 << 5)
+
+/**
+ * Obtains NSEC3 parameters from RR.
+ * @param params NSEC3 parameters structure to be set.
+ * @param nsec3  NSEC3 RR containing the parameters.
+ * @return       0 or error code.
+ */
+static int nsec3_parameters(dnssec_nsec3_params_t *params, const knot_rrset_t *nsec3)
+{
+	assert(params && nsec3);
+
+	const knot_rdata_t *rr = knot_rdataset_at(&nsec3->rrs, 0);
+	assert(rr);
+
+	/* Every NSEC3 RR contains data from NSEC3PARAMS. */
+	const size_t SALT_OFFSET = 5; /* First 5 octets contain { Alg, Flags, Iterations, Salt length } */
+	dnssec_binary_t rdata = {
+		.size = SALT_OFFSET + (size_t)knot_nsec3_salt_len(nsec3->rrs.rdata),
+		.data = /*const-cast*/(uint8_t *)rr->data,
+	};
+	if (rdata.size > rr->len)
+		return kr_error(EMSGSIZE);
+
+	int ret = dnssec_nsec3_params_from_rdata(params, &rdata);
+	if (ret != DNSSEC_EOK) {
+		return kr_error(EINVAL);
+	}
+
+	return kr_ok();
+}
+
+/**
+ * Computes a hash of a given domain name.
+ * @param hash   Resulting hash, must be freed.
+ * @param params NSEC3 parameters.
+ * @param name   Domain name to be hashed.
+ * @return       0 or error code.
+ */
+static int hash_name(dnssec_binary_t *hash, const dnssec_nsec3_params_t *params,
+                     const knot_dname_t *name)
+{
+	assert(hash && params);
+	if (!name)
+		return kr_error(EINVAL);
+	if (params->iterations > KR_NSEC3_MAX_ITERATIONS) {
+		assert(false); // This if is mainly defensive; it shouldn't happen.
+		return kr_error(EINVAL);
+	}
+
+	dnssec_binary_t dname = {
+		.size = knot_dname_size(name),
+		.data = (uint8_t *) name,
+	};
+
+	int ret = dnssec_nsec3_hash(&dname, params, hash);
+	if (ret != DNSSEC_EOK) {
+		return kr_error(EINVAL);
+	}
+
+	return kr_ok();
+}
+
+/**
+ * Read hash from NSEC3 owner name and store its binary form.
+ * @param hash          Buffer to be written.
+ * @param max_hash_size Maximal has size.
+ * @param nsec3         NSEC3 RR.
+ * @return              0 or error code.
+ */
+static int read_owner_hash(dnssec_binary_t *hash, size_t max_hash_size, const knot_rrset_t *nsec3)
+{
+	assert(hash && nsec3);
+	assert(hash->data);
+
+	int32_t ret = base32hex_decode(nsec3->owner + 1, nsec3->owner[0], hash->data, max_hash_size);
+	if (ret < 0) {
+		return kr_error(EILSEQ);
+	}
+	hash->size = ret;
+
+	return kr_ok();
+}
+
+#define MAX_HASH_BYTES 64
+/**
+ * Closest (provable) encloser match (RFC5155 7.2.1, bullet 1).
+ * @param flags   Flags to be set according to check outcome.
+ * @param nsec3   NSEC3 RR.
+ * @param name    Name to be checked.
+ * @param skipped Number of skipped labels to find closest (provable) match.
+ * @return        0 or error code.
+ */
+static int closest_encloser_match(int *flags, const knot_rrset_t *nsec3,
+                                  const knot_dname_t *name, unsigned *skipped)
+{
+	assert(flags && nsec3 && name && skipped);
+
+	uint8_t hash_data[MAX_HASH_BYTES] = {0, };
+	dnssec_binary_t owner_hash = { 0, hash_data };
+	dnssec_nsec3_params_t params = { 0, };
+	dnssec_binary_t name_hash = { 0, };
+
+	int ret = read_owner_hash(&owner_hash, MAX_HASH_BYTES, nsec3);
+	if (ret != 0) {
+		goto fail;
+	}
+
+	ret = nsec3_parameters(&params, nsec3);
+	if (ret != 0) {
+		goto fail;
+	}
+
+	/* Root label has no encloser */
+	if (!name[0]) {
+		ret = kr_error(ENOENT);
+		goto fail;
+	}
+
+	const knot_dname_t *encloser = knot_wire_next_label(name, NULL);
+	*skipped = 1;
+
+	while(encloser) {
+		ret = hash_name(&name_hash, &params, encloser);
+		if (ret != 0) {
+			goto fail;
+		}
+
+		if ((owner_hash.size == name_hash.size) &&
+		    (memcmp(owner_hash.data, name_hash.data, owner_hash.size) == 0)) {
+			dnssec_binary_free(&name_hash);
+			*flags |= FLG_CLOSEST_PROVABLE_ENCLOSER;
+			break;
+		}
+
+		dnssec_binary_free(&name_hash);
+
+		if (!encloser[0])
+			break;
+		encloser = knot_wire_next_label(encloser, NULL);
+		++(*skipped);
+	}
+
+	ret = kr_ok();
+
+fail:
+	if (params.salt.data) {
+		dnssec_nsec3_params_free(&params);
+	}
+	if (name_hash.data) {
+		dnssec_binary_free(&name_hash);
+	}
+	return ret;
+}
+
+/**
+ * Checks whether NSEC3 RR covers the supplied name (RFC5155 7.2.1, bullet 2).
+ * @param flags Flags to be set according to check outcome.
+ * @param nsec3 NSEC3 RR.
+ * @param name  Name to be checked.
+ * @return      0 or error code.
+ */
+static int covers_name(int *flags, const knot_rrset_t *nsec3, const knot_dname_t *name)
+{
+	assert(flags && nsec3 && name);
+
+	uint8_t hash_data[MAX_HASH_BYTES] = { 0, };
+	dnssec_binary_t owner_hash = { 0, hash_data };
+	dnssec_nsec3_params_t params = { 0, };
+	dnssec_binary_t name_hash = { 0, };
+
+	int ret = read_owner_hash(&owner_hash, MAX_HASH_BYTES, nsec3);
+	if (ret != 0) {
+		goto fail;
+	}
+
+	ret = nsec3_parameters(&params, nsec3);
+	if (ret != 0) {
+		goto fail;
+	}
+
+	ret = hash_name(&name_hash, &params, name);
+	if (ret != 0) {
+		goto fail;
+	}
+
+	uint8_t next_size = knot_nsec3_next_len(nsec3->rrs.rdata);
+	const uint8_t *next_hash = knot_nsec3_next(nsec3->rrs.rdata);
+
+	if ((next_size > 0) && (owner_hash.size == next_size) && (name_hash.size == next_size)) {
+		/* All hash lengths must be same. */
+		const uint8_t *ownrd = owner_hash.data;
+		const uint8_t *nextd = next_hash;
+		int covered = 0;
+		int greater_then_owner = (memcmp(ownrd, name_hash.data, next_size) < 0);
+		int less_then_next = (memcmp(name_hash.data, nextd, next_size) < 0);
+		if (memcmp(ownrd, nextd, next_size) < 0) {
+			/*
+			 * 0 (...) owner ... next (...) MAX
+			 *                ^
+			 *                name
+			 * ==>
+			 * (owner < name) && (name < next)
+			 */
+			covered = ((greater_then_owner) && (less_then_next));
+		} else {
+			/*
+			 * owner ... MAX, 0 ... next
+			 *        ^     ^    ^
+			 *        name  name name
+			 * =>
+			 * (owner < name) || (name < next)
+			 */
+			covered = ((greater_then_owner) || (less_then_next));
+		}
+
+		if (covered) {
+			*flags |= FLG_NAME_COVERED;
+
+			uint8_t nsec3_flags = knot_nsec3_flags(nsec3->rrs.rdata);
+			if (nsec3_flags & ~OPT_OUT_BIT) {
+				/* RFC5155 3.1.2 */
+				ret = kr_error(EINVAL);
+			} else {
+				ret = kr_ok();
+			}
+		}
+	}
+
+fail:
+	if (params.salt.data) {
+		dnssec_nsec3_params_free(&params);
+	}
+	if (name_hash.data) {
+		dnssec_binary_free(&name_hash);
+	}
+	return ret;
+}
+
+/**
+ * Checks whether NSEC3 RR has the opt-out bit set.
+ * @param flags Flags to be set according to check outcome.
+ * @param nsec3 NSEC3 RR.
+ * @param name  Name to be checked.
+ * @return      0 or error code.
+ */
+static bool has_optout(const knot_rrset_t *nsec3)
+{
+	if (!nsec3) {
+		return false;
+	}
+
+	uint8_t nsec3_flags = knot_nsec3_flags(nsec3->rrs.rdata);
+	if (nsec3_flags & ~OPT_OUT_BIT) {
+		/* RFC5155 3.1.2 */
+		return false;
+	}
+
+	return nsec3_flags & OPT_OUT_BIT;
+}
+
+/**
+ * Checks whether NSEC3 RR matches the supplied name.
+ * @param flags Flags to be set according to check outcome.
+ * @param nsec3 NSEC3 RR.
+ * @param name  Name to be checked.
+ * @return      0 if matching, >0 if not (abs(ENOENT)), or error code (<0).
+ */
+static int matches_name(const knot_rrset_t *nsec3, const knot_dname_t *name)
+{
+	assert(nsec3 && name);
+
+	uint8_t hash_data[MAX_HASH_BYTES] = { 0, };
+	dnssec_binary_t owner_hash = { 0, hash_data };
+	dnssec_nsec3_params_t params = { 0, };
+	dnssec_binary_t name_hash = { 0, };
+
+	int ret = read_owner_hash(&owner_hash, MAX_HASH_BYTES, nsec3);
+	if (ret != 0) {
+		goto fail;
+	}
+
+	ret = nsec3_parameters(&params, nsec3);
+	if (ret != 0) {
+		goto fail;
+	}
+
+	ret = hash_name(&name_hash, &params, name);
+	if (ret != 0) {
+		goto fail;
+	}
+
+	if ((owner_hash.size == name_hash.size) &&
+	    (memcmp(owner_hash.data, name_hash.data, owner_hash.size) == 0)) {
+		ret = kr_ok();
+	} else {
+		ret = abs(ENOENT);
+	}
+
+fail:
+	if (params.salt.data) {
+		dnssec_nsec3_params_free(&params);
+	}
+	if (name_hash.data) {
+		dnssec_binary_free(&name_hash);
+	}
+	return ret;
+}
+#undef MAX_HASH_BYTES
+
+/**
+ * Prepends an asterisk label to given name.
+ *
+ * @param tgt  Target buffer to write domain name into.
+ * @param name Name to be added to the asterisk.
+ * @return     Size of the resulting name or error code.
+ */
+static int prepend_asterisk(uint8_t *tgt, size_t maxlen, const knot_dname_t *name)
+{
+	assert(maxlen >= 3);
+	memcpy(tgt, "\1*", 3);
+	return knot_dname_to_wire(tgt + 2, name, maxlen - 2);
+}
+
+/**
+ * Closest encloser proof (RFC5155 7.2.1).
+ * @note No RRSIGs are validated.
+ * @param pkt                     Packet structure to be processed.
+ * @param section_id              Packet section to be processed.
+ * @param sname                   Name to be checked.
+ * @param encloser_name           Returned matching encloser name, if found.
+ * @param matching_encloser_nsec3 Pointer to matching encloser NSEC RRSet.
+ * @param covering_next_nsec3     Pointer to covering next closer NSEC3 RRSet.
+ * @return                        0 or error code.
+ */
+static int closest_encloser_proof(const knot_pkt_t *pkt,
+				  knot_section_t section_id,
+				  const knot_dname_t *sname,
+				  const knot_dname_t **encloser_name,
+				  const knot_rrset_t **matching_encloser_nsec3,
+				  const knot_rrset_t **covering_next_nsec3)
+{
+	const knot_pktsection_t *sec = knot_pkt_section(pkt, section_id);
+	if (!sec || !sname) {
+		return kr_error(EINVAL);
+	}
+
+	const knot_rrset_t *matching = NULL;
+	const knot_rrset_t *covering = NULL;
+
+	int flags = 0;
+	const knot_dname_t *next_closer = NULL;
+	for (unsigned i = 0; i < sec->count; ++i) {
+		const knot_rrset_t *rrset = knot_pkt_rr(sec, i);
+		if (rrset->type != KNOT_RRTYPE_NSEC3) {
+			continue;
+		}
+		/* Also skip the NSEC3-to-match an ancestor of sname if it's
+		 * a parent-side delegation, as that would mean the owner
+		 * does not really exist (authoritatively in this zone,
+		 * even in case of opt-out).
+		 */
+		const uint8_t *bm = knot_nsec3_bitmap(rrset->rrs.rdata);
+		uint16_t bm_size = knot_nsec3_bitmap_len(rrset->rrs.rdata);
+		if (kr_nsec_children_in_zone_check(bm, bm_size) != 0) {
+			continue; /* no fatal errors from bad RRs */
+		}
+		/* Match the NSEC3 to sname or one of its ancestors. */
+		unsigned skipped = 0;
+		flags = 0;
+		int ret = closest_encloser_match(&flags, rrset, sname, &skipped);
+		if (ret != 0) {
+			return ret;
+		}
+		if (!(flags & FLG_CLOSEST_PROVABLE_ENCLOSER)) {
+			continue;
+		}
+		matching = rrset;
+		/* Construct the next closer name and try to cover it. */
+		--skipped;
+		next_closer = sname;
+		for (unsigned j = 0; j < skipped; ++j) {
+			assert(next_closer[0]);
+			next_closer = knot_wire_next_label(next_closer, NULL);
+		}
+		for (unsigned j = 0; j < sec->count; ++j) {
+			const knot_rrset_t *rrset_j = knot_pkt_rr(sec, j);
+			if (rrset_j->type != KNOT_RRTYPE_NSEC3) {
+				continue;
+			}
+			ret = covers_name(&flags, rrset_j, next_closer);
+			if (ret != 0) {
+				return ret;
+			}
+			if (flags & FLG_NAME_COVERED) {
+				covering = rrset_j;
+				break;
+			}
+		}
+		if (flags & FLG_NAME_COVERED) {
+			break;
+		}
+		flags = 0; //
+	}
+
+	if ((flags & FLG_CLOSEST_PROVABLE_ENCLOSER) && (flags & FLG_NAME_COVERED) && next_closer) {
+		if (encloser_name && next_closer[0]) {
+			*encloser_name = knot_wire_next_label(next_closer, NULL);
+		}
+		if (matching_encloser_nsec3) {
+			*matching_encloser_nsec3 = matching;
+		}
+		if (covering_next_nsec3) {
+			*covering_next_nsec3 = covering;
+		}
+		return kr_ok();
+	}
+
+	return kr_error(ENOENT);
+}
+
+/**
+ * Check whether any NSEC3 RR covers a wildcard RR at the closer encloser.
+ * @param pkt        Packet structure to be processed.
+ * @param section_id Packet section to be processed.
+ * @param encloser   Closest (provable) encloser domain name.
+ * @return           0 or error code:
+ *                   KNOT_ERANGE - NSEC3 RR (that covers a wildcard)
+ *                   has been found, but has opt-out flag set;
+ *                   otherwise - error.
+ */
+static int covers_closest_encloser_wildcard(const knot_pkt_t *pkt, knot_section_t section_id,
+                                            const knot_dname_t *encloser)
+{
+	const knot_pktsection_t *sec = knot_pkt_section(pkt, section_id);
+	if (!sec || !encloser) {
+		return kr_error(EINVAL);
+	}
+
+	uint8_t wildcard[KNOT_DNAME_MAXLEN];
+	wildcard[0] = 1;
+	wildcard[1] = '*';
+	int encloser_len = knot_dname_size(encloser);
+	if (encloser_len < 0) {
+		return encloser_len;
+	}
+	memcpy(wildcard + 2, encloser, encloser_len);
+
+	int flags = 0;
+	for (unsigned i = 0; i < sec->count; ++i) {
+		const knot_rrset_t *rrset = knot_pkt_rr(sec, i);
+		if (rrset->type != KNOT_RRTYPE_NSEC3) {
+			continue;
+		}
+		int ret = covers_name(&flags, rrset, wildcard);
+		if (ret != 0) {
+			return ret;
+		}
+		if (flags & FLG_NAME_COVERED) {
+			return has_optout(rrset) ?
+			       kr_error(KNOT_ERANGE) : kr_ok();
+		}
+	}
+
+	return kr_error(ENOENT);
+}
+
+int kr_nsec3_name_error_response_check(const knot_pkt_t *pkt, knot_section_t section_id,
+                                       const knot_dname_t *sname)
+{
+	const knot_dname_t *encloser = NULL;
+	const knot_rrset_t *covering_next_nsec3 = NULL;
+	int ret = closest_encloser_proof(pkt, section_id, sname,
+					 &encloser, NULL, &covering_next_nsec3);
+	if (ret != 0) {
+		return ret;
+	}
+	ret = covers_closest_encloser_wildcard(pkt, section_id, encloser);
+	if (ret != 0) {
+		/* OK, but NSEC3 for wildcard at encloser has opt-out;
+		 * or error */
+		return ret;
+	}
+	/* Closest encloser proof is OK and
+	 * NSEC3 for wildcard has been found and optout flag is not set.
+	 * Now check if NSEC3 that covers next closer name has opt-out. */
+	return has_optout(covering_next_nsec3) ?
+	       kr_error(KNOT_ERANGE) : kr_ok();
+}
+
+/**
+ * Search the packet section for a matching NSEC3 with nodata-proving bitmap.
+ * @param pkt        Packet structure to be processed.
+ * @param section_id Packet section to be processed.
+ * @param sname      Name to be checked.
+ * @param stype      Type to be checked.
+ * @return           0 or error code.
+ * @note             This does NOT check the opt-out case if type is DS;
+ *                   see RFC 5155 8.6.
+ */
+static int nodata_find(const knot_pkt_t *pkt, knot_section_t section_id,
+			const knot_dname_t *name, const uint16_t type)
+{
+	const knot_pktsection_t *sec = knot_pkt_section(pkt, section_id);
+	if (!sec || !name) {
+		return kr_error(EINVAL);
+	}
+
+	for (unsigned i = 0; i < sec->count; ++i) {
+		const knot_rrset_t *nsec3 = knot_pkt_rr(sec, i);
+		/* Records causing any errors are simply skipped. */
+		if (nsec3->type != KNOT_RRTYPE_NSEC3
+		    || matches_name(nsec3, name) != kr_ok()) {
+			continue;
+			/* LATER(optim.): we repeatedly recompute the hash of `name` */
+		}
+
+		const uint8_t *bm = knot_nsec3_bitmap(nsec3->rrs.rdata);
+		uint16_t bm_size = knot_nsec3_bitmap_len(nsec3->rrs.rdata);
+		if (kr_nsec_bitmap_nodata_check(bm, bm_size, type, nsec3->owner) == kr_ok()) {
+			return kr_ok();
+		}
+	}
+
+	return kr_error(ENOENT);
+}
+
+/**
+ * Check whether NSEC3 RR matches a wildcard at the closest encloser and has given type bit missing.
+ * @param pkt        Packet structure to be processed.
+ * @param section_id Packet section to be processed.
+ * @param encloser   Closest (provable) encloser domain name.
+ * @param stype      Type to be checked.
+ * @return           0 or error code.
+ */
+static int matches_closest_encloser_wildcard(const knot_pkt_t *pkt, knot_section_t section_id,
+                                             const knot_dname_t *encloser, uint16_t stype)
+{
+	const knot_pktsection_t *sec = knot_pkt_section(pkt, section_id);
+	if (!sec || !encloser) {
+		return kr_error(EINVAL);
+	}
+
+	uint8_t wildcard[KNOT_DNAME_MAXLEN]; /**< the source of synthesis */
+	int ret = prepend_asterisk(wildcard, sizeof(wildcard), encloser);
+	if (ret < 0) {
+		return ret;
+	}
+	assert(ret >= 3);
+	return nodata_find(pkt, section_id, wildcard, stype);
+}
+
+int kr_nsec3_wildcard_answer_response_check(const knot_pkt_t *pkt, knot_section_t section_id,
+                                            const knot_dname_t *sname, int trim_to_next)
+{
+	const knot_pktsection_t *sec = knot_pkt_section(pkt, section_id);
+	if (!sec || !sname) {
+		return kr_error(EINVAL);
+	}
+
+	/* Compute the next closer name. */
+	for (int i = 0; i < trim_to_next; ++i) {
+		assert(sname[0]);
+		sname = knot_wire_next_label(sname, NULL);
+	}
+
+	int flags = 0;
+	for (unsigned i = 0; i < sec->count; ++i) {
+		const knot_rrset_t *rrset = knot_pkt_rr(sec, i);
+		if (rrset->type != KNOT_RRTYPE_NSEC3) {
+			continue;
+		}
+		int ret = covers_name(&flags, rrset, sname);
+		if (ret != 0) {
+			return ret;
+		}
+		if (flags & FLG_NAME_COVERED) {
+			return has_optout(rrset) ?
+			       kr_error(KNOT_ERANGE) : kr_ok();
+		}
+	}
+
+	return kr_error(ENOENT);
+}
+
+
+int kr_nsec3_no_data(const knot_pkt_t *pkt, knot_section_t section_id,
+                     const knot_dname_t *sname, uint16_t stype)
+{
+	/* DS record may be also matched by an existing NSEC3 RR. */
+	int ret = nodata_find(pkt, section_id, sname, stype);
+	if (ret == 0) {
+		/* Satisfies RFC5155 8.5 and 8.6, both first paragraph. */
+		return ret;
+	}
+
+	/* Find closest provable encloser. */
+	const knot_dname_t *encloser_name = NULL;
+	const knot_rrset_t *covering_next_nsec3 = NULL;
+	ret = closest_encloser_proof(pkt, section_id, sname, &encloser_name,
+                                     NULL, &covering_next_nsec3);
+	if (ret != 0) {
+		return ret;
+	}
+
+	assert(encloser_name && covering_next_nsec3);
+	ret = matches_closest_encloser_wildcard(pkt, section_id,
+	                                         encloser_name, stype);
+	if (ret == 0) {
+		/* Satisfies RFC5155 8.7 */
+		if (has_optout(covering_next_nsec3)) {
+			/* Opt-out is detected.
+			 * Despite the fact that all records
+			 * in the packet can be properly signed,
+			 * AD bit must not be set due to rfc5155 9.2.
+			 * Return appropriate code to the caller */
+			ret = kr_error(KNOT_ERANGE);
+		}
+		return ret;
+	}
+
+	if (!has_optout(covering_next_nsec3)) {
+		/* Bogus */
+		ret = kr_error(ENOENT);
+	} else {
+		/* 
+		 * Satisfies RFC5155 8.6 (QTYPE == DS), 2nd paragraph.
+		 * Also satisfies ERRATA 3441 8.5 (QTYPE != DS), 3rd paragraph.
+		 * - (wildcard) empty nonterminal
+		 * derived from unsecure delegation.
+		 * Denial of existence can not be proven.
+		 * Set error code to proceed unsecure.
+		 */
+		ret = kr_error(KNOT_ERANGE);
+	}
+
+	return ret;
+}
+
+int kr_nsec3_ref_to_unsigned(const knot_pkt_t *pkt)
+{
+	const knot_pktsection_t *sec = knot_pkt_section(pkt, KNOT_AUTHORITY);
+	if (!sec) {
+		return kr_error(EINVAL);
+	}
+	for (unsigned i = 0; i < sec->count; ++i) {
+		const knot_rrset_t *ns = knot_pkt_rr(sec, i);
+		if (ns->type == KNOT_RRTYPE_DS) {
+			return kr_error(EEXIST);
+		}
+		if (ns->type != KNOT_RRTYPE_NS) {
+			continue;
+		}
+
+		int flags = 0;
+		bool nsec3_found = false;
+		for (unsigned j = 0; j < sec->count; ++j) {
+			const knot_rrset_t *nsec3 = knot_pkt_rr(sec, j);
+			if (nsec3->type == KNOT_RRTYPE_DS) {
+				return kr_error(EEXIST);
+			}
+			if (nsec3->type != KNOT_RRTYPE_NSEC3) {
+				continue;
+			}
+			nsec3_found = true;
+			/* nsec3 found, check if owner name matches the delegation name.
+			 * Just skip in case of *any* errors. */
+			if (matches_name(nsec3, ns->owner) != kr_ok()) {
+				continue;
+			}
+
+			const uint8_t *bm = knot_nsec3_bitmap(nsec3->rrs.rdata);
+			uint16_t bm_size = knot_nsec3_bitmap_len(nsec3->rrs.rdata);
+			if (!bm) {
+				return kr_error(EINVAL);
+			}
+			if (dnssec_nsec_bitmap_contains(bm, bm_size,
+							  KNOT_RRTYPE_NS) &&
+			    !dnssec_nsec_bitmap_contains(bm, bm_size,
+							  KNOT_RRTYPE_DS) &&
+			    !dnssec_nsec_bitmap_contains(bm, bm_size,
+							  KNOT_RRTYPE_SOA)) {
+				/* Satisfies rfc5155, 8.9. paragraph 2 */
+				return kr_ok();
+			}
+		}
+		if (!nsec3_found) {
+			return kr_error(DNSSEC_NOT_FOUND);
+		}
+		if (flags & FLG_NAME_MATCHED) {
+			/* nsec3 which owner matches
+			 * the delegation name was found,
+			 * but nsec3 type bitmap contains wrong types
+			 */
+			return kr_error(EINVAL);
+		}
+		/* nsec3 that matches the delegation was not found.
+		 * Check rfc5155, 8.9. paragraph 4.
+		 * Find closest provable encloser.
+		 */
+		const knot_dname_t *encloser_name = NULL;
+		const knot_rrset_t *covering_next_nsec3 = NULL;
+		int ret = closest_encloser_proof(pkt, KNOT_AUTHORITY, ns->owner,
+				&encloser_name, NULL, &covering_next_nsec3);
+		if (ret != 0) {
+			return kr_error(EINVAL);
+		}
+
+		if (has_optout(covering_next_nsec3)) {
+			return kr_error(KNOT_ERANGE);
+		} else {
+			return kr_error(EINVAL);
+		}
+	}
+	return kr_error(EINVAL);
+}
+
+int kr_nsec3_matches_name_and_type(const knot_rrset_t *nsec3,
+				   const knot_dname_t *name, uint16_t type)
+{
+	/* It's not secure enough to just check a single bit for (some) other types,
+	 * but we don't (currently) only use this API for NS.  See RFC 6840 sec. 4.
+	 */
+	if (type != KNOT_RRTYPE_NS) {
+		assert(!EINVAL);
+		return kr_error(EINVAL);
+	}
+	int ret = matches_name(nsec3, name);
+	if (ret) {
+		return kr_error(ret);
+	}
+	const uint8_t *bm = knot_nsec3_bitmap(nsec3->rrs.rdata);
+	uint16_t bm_size = knot_nsec3_bitmap_len(nsec3->rrs.rdata);
+	if (!bm) {
+		return kr_error(EINVAL);
+	}
+	if (dnssec_nsec_bitmap_contains(bm, bm_size, type)) {
+		return kr_ok();
+	} else {
+		return kr_error(ENOENT);
+	}
+}
diff --git a/lib/dnssec/nsec3.h b/lib/dnssec/nsec3.h
new file mode 100644
index 0000000..1e316f5
--- /dev/null
+++ b/lib/dnssec/nsec3.h
@@ -0,0 +1,82 @@
+/*  Copyright (C) 2015-2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#pragma once
+
+#include <libknot/packet/pkt.h>
+
+/** High numbers in NSEC3 iterations don't really help security
+ *
+ * ...so we avoid doing all the work.  The value is a current compromise;
+ * zones shooting over get downgraded to insecure status.
+ *
+ * Original restriction wasn't that strict:
+   https://datatracker.ietf.org/doc/html/rfc5155#section-10.3
+ * but there is discussion about officially lowering the limits:
+   https://tools.ietf.org/id/draft-hardaker-dnsop-nsec3-guidance-02.html#section-2.3
+ */
+#define KR_NSEC3_MAX_ITERATIONS 150
+
+/**
+ * Name error response check (RFC5155 7.2.2).
+ * @note No RRSIGs are validated.
+ * @param pkt        Packet structure to be processed.
+ * @param section_id Packet section to be processed.
+ * @param sname      Name to be checked.
+ * @return           0 or error code.
+ */
+int kr_nsec3_name_error_response_check(const knot_pkt_t *pkt, knot_section_t section_id,
+                                       const knot_dname_t *sname);
+
+/**
+ * Wildcard answer response check (RFC5155 7.2.6).
+ * @param pkt          Packet structure to be processed.
+ * @param section_id   Packet section to be processed.
+ * @param sname        Name to be checked.
+ * @param trim_to_next Number of labels to remove to obtain next closer name.
+ * @return             0 or error code:
+ *                     KNOT_ERANGE - NSEC3 RR that covers a wildcard
+ *                     has been found, but has opt-out flag set;
+ *                     otherwise - error.
+ */
+int kr_nsec3_wildcard_answer_response_check(const knot_pkt_t *pkt, knot_section_t section_id,
+                                            const knot_dname_t *sname, int trim_to_next);
+
+/**
+ * Authenticated denial of existence according to RFC5155 8.5 and 8.7.
+ * @note No RRSIGs are validated.
+ * @param pkt        Packet structure to be processed.
+ * @param section_id Packet section to be processed.
+ * @param sname      Queried domain name.
+ * @param stype      Queried type.
+ * @return           0 or error code:
+ *                   DNSSEC_NOT_FOUND - neither ds nor nsec records
+ *                   were not found.
+ *                   KNOT_ERANGE - denial of existence can't be proven
+ *                   due to opt-out, otherwise - bogus.
+ */
+int kr_nsec3_no_data(const knot_pkt_t *pkt, knot_section_t section_id,
+                     const knot_dname_t *sname, uint16_t stype);
+
+/**
+ * Referral to unsigned subzone check (RFC5155 8.9).
+ * @note 	     No RRSIGs are validated.
+ * @param pkt        Packet structure to be processed.
+ * @return           0 or error code:
+ *                   KNOT_ERANGE - denial of existence can't be proven
+ *                   due to opt-out.
+ *                   EEXIST - ds record was found.
+ *                   EINVAL - bogus.
+ */
+int kr_nsec3_ref_to_unsigned(const knot_pkt_t *pkt);
+
+/**
+ * Checks whether supplied NSEC3 RR matches the supplied name and NS type.
+ * @param nsec3 NSEC3 RR.
+ * @param name  Name to be checked.
+ * @param type  Type to be checked.  Only use with NS!  TODO
+ * @return      0 or error code.
+ */
+int kr_nsec3_matches_name_and_type(const knot_rrset_t *nsec3,
+				   const knot_dname_t *name, uint16_t type);
diff --git a/lib/dnssec/signature.c b/lib/dnssec/signature.c
new file mode 100644
index 0000000..fed0cf4
--- /dev/null
+++ b/lib/dnssec/signature.c
@@ -0,0 +1,300 @@
+/*  Copyright (C) 2015-2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#include <arpa/inet.h>
+#include <assert.h>
+#include <string.h>
+
+#include <libdnssec/error.h>
+#include <libdnssec/key.h>
+#include <libdnssec/sign.h>
+#include <libknot/descriptor.h>
+#include <libknot/packet/rrset-wire.h>
+#include <libknot/packet/wire.h>
+#include <libknot/rrset.h>
+#include <libknot/rrtype/rrsig.h>
+#include <libknot/rrtype/ds.h>
+
+#include "lib/defines.h"
+#include "lib/utils.h"
+#include "lib/dnssec/signature.h"
+
+#include "contrib/wire.h"
+
+static int authenticate_ds(const dnssec_key_t *key, dnssec_binary_t *ds_rdata, uint8_t digest_type)
+{
+	/* Compute DS RDATA from the DNSKEY. */
+	dnssec_binary_t computed_ds = { 0, };
+	int ret = dnssec_key_create_ds(key, digest_type, &computed_ds);
+	if (ret != DNSSEC_EOK) {
+		goto fail;
+	}
+
+	/* DS records contain algorithm, key tag and the digest.
+	 * Therefore the comparison of the two DS is sufficient.
+	 */
+	ret = (ds_rdata->size == computed_ds.size) &&
+	    (memcmp(ds_rdata->data, computed_ds.data, ds_rdata->size) == 0);
+	ret = ret ? kr_ok() : kr_error(ENOENT);
+
+fail:
+	dnssec_binary_free(&computed_ds);
+	return kr_error(ret);
+}
+
+int kr_authenticate_referral(const knot_rrset_t *ref, const dnssec_key_t *key)
+{
+	assert(ref && key);
+	if (ref->type != KNOT_RRTYPE_DS) {
+		return kr_error(EINVAL);
+	}
+
+	/* Try all possible DS records */
+	int ret = 0;
+	knot_rdata_t *rd = ref->rrs.rdata;
+	for (uint16_t i = 0; i < ref->rrs.count; ++i) {
+		dnssec_binary_t ds_rdata = {
+			.size = rd->len,
+			.data = rd->data
+		};
+		ret = authenticate_ds(key, &ds_rdata, knot_ds_digest_type(rd));
+		if (ret == 0) { /* Found a good DS */
+			return kr_ok();
+		}
+		rd = knot_rdataset_next(rd);
+	}
+
+	return kr_error(ret);
+}
+
+/**
+ * Adjust TTL in wire format.
+ * @param wire      RR Set in wire format.
+ * @param wire_size Size of the wire data portion.
+ * @param new_ttl   TTL value to be set for all RRs.
+ * @return          0 or error code.
+ */
+static int adjust_wire_ttl(uint8_t *wire, size_t wire_size, uint32_t new_ttl)
+{
+	assert(wire);
+	static_assert(sizeof(uint16_t) == 2, "uint16_t must be exactly 2 bytes");
+	static_assert(sizeof(uint32_t) == 4, "uint32_t) must be exactly 4 bytes");
+	uint16_t rdlen;
+
+	int ret;
+
+	new_ttl = htonl(new_ttl);
+
+	size_t i = 0;
+	/* RR wire format in RFC1035 3.2.1 */
+	while(i < wire_size) {
+		ret = knot_dname_size(wire + i);
+		if (ret < 0) {
+			return ret;
+		}
+		i += ret + 4;
+		memcpy(wire + i, &new_ttl, sizeof(uint32_t));
+		i += sizeof(uint32_t);
+
+		memcpy(&rdlen, wire + i, sizeof(uint16_t));
+		rdlen = ntohs(rdlen);
+		i += sizeof(uint16_t) + rdlen;
+
+		assert(i <= wire_size);
+	}
+
+	return kr_ok();
+}
+
+/*!
+ * \brief Add RRSIG RDATA without signature to signing context.
+ *
+ * Requires signer name in RDATA in canonical form.
+ *
+ * \param ctx   Signing context.
+ * \param rdata Pointer to RRSIG RDATA.
+ *
+ * \return Error code, KNOT_EOK if successful.
+ */
+#define RRSIG_RDATA_SIGNER_OFFSET 18
+static int sign_ctx_add_self(dnssec_sign_ctx_t *ctx, const uint8_t *rdata)
+{
+	assert(ctx);
+	assert(rdata);
+
+	int result;
+
+	// static header
+
+	dnssec_binary_t header = {
+		.data = (uint8_t *)rdata,
+		.size = RRSIG_RDATA_SIGNER_OFFSET,
+	};
+
+	result = dnssec_sign_add(ctx, &header);
+	if (result != DNSSEC_EOK) {
+		return result;
+	}
+
+	// signer name
+
+	const uint8_t *rdata_signer = rdata + RRSIG_RDATA_SIGNER_OFFSET;
+	dnssec_binary_t signer = { 0 };
+	signer.data = knot_dname_copy(rdata_signer, NULL);
+	signer.size = knot_dname_size(signer.data);
+
+	result = dnssec_sign_add(ctx, &signer);
+	free(signer.data);
+
+	return result;
+}
+#undef RRSIG_RDATA_SIGNER_OFFSET
+
+/*!
+ * \brief Add covered RRs to signing context.
+ *
+ * Requires all DNAMEs in canonical form and all RRs ordered canonically.
+ *
+ * \param ctx      Signing context.
+ * \param covered  Covered RRs.
+ *
+ * \return Error code, KNOT_EOK if successful.
+ */
+static int sign_ctx_add_records(dnssec_sign_ctx_t *ctx, const knot_rrset_t *covered,
+                                uint32_t orig_ttl, int trim_labels)
+{
+	if (!ctx || !covered || trim_labels < 0) {
+		return kr_error(EINVAL);
+	}
+
+	// huge block of rrsets can be optionally created
+	static uint8_t wire_buffer[KNOT_WIRE_MAX_PKTSIZE];
+	int written = knot_rrset_to_wire(covered, wire_buffer, sizeof(wire_buffer), NULL);
+	if (written < 0) {
+		return written;
+	}
+
+	/* Set original ttl. */
+	int ret = adjust_wire_ttl(wire_buffer, written, orig_ttl);
+	if (ret != 0) {
+		return ret;
+	}
+
+	if (!trim_labels) {
+		const dnssec_binary_t wire_binary = {
+			.size = written,
+			.data = wire_buffer
+		};
+		return dnssec_sign_add(ctx, &wire_binary);
+	}
+
+	/* RFC4035 5.3.2
+	 * Remove leftmost labels and replace them with '*.'
+	 * for each RR in covered.
+	 */
+	uint8_t *beginp = wire_buffer;
+	for (uint16_t i = 0; i < covered->rrs.count; ++i) {
+		/* RR(i) = name | type | class | OrigTTL | RDATA length | RDATA */
+		for (int j = 0; j < trim_labels; ++j) {
+			assert(beginp[0]);
+			beginp = (uint8_t *) knot_wire_next_label(beginp, NULL);
+			assert(beginp != NULL);
+		}
+		*(--beginp) = '*';
+		*(--beginp) = 1;
+		const size_t rdatalen_offset = knot_dname_size(beginp) + /* name */
+			sizeof(uint16_t) + /* type */
+			sizeof(uint16_t) + /* class */
+			sizeof(uint32_t);  /* OrigTTL */
+		const uint8_t *rdatalen_ptr = beginp + rdatalen_offset;
+		const uint16_t rdata_size = wire_read_u16(rdatalen_ptr);
+		const size_t rr_size = rdatalen_offset +
+			sizeof(uint16_t) + /* RDATA length */
+			rdata_size;        /* RDATA */
+		const dnssec_binary_t wire_binary = {
+			.size = rr_size,
+			.data = beginp
+		};
+		ret = dnssec_sign_add(ctx, &wire_binary);
+		if (ret != 0) {
+			break;
+		}
+		beginp += rr_size;
+	}
+	return ret;
+}
+
+/*!
+ * \brief Add all data covered by signature into signing context.
+ *
+ * RFC 4034: The signature covers RRSIG RDATA field (excluding the signature)
+ * and all matching RR records, which are ordered canonically.
+ *
+ * Requires all DNAMEs in canonical form and all RRs ordered canonically.
+ *
+ * \param ctx          Signing context.
+ * \param rrsig_rdata  RRSIG RDATA with populated fields except signature.
+ * \param covered      Covered RRs.
+ *
+ * \return Error code, KNOT_EOK if successful.
+ */
+/* TODO -- Taken from knot/src/knot/dnssec/rrset-sign.c. Re-write for better fit needed. */
+static int sign_ctx_add_data(dnssec_sign_ctx_t *ctx, const uint8_t *rrsig_rdata,
+                             const knot_rrset_t *covered, uint32_t orig_ttl, int trim_labels)
+{
+	int result = sign_ctx_add_self(ctx, rrsig_rdata);
+	if (result != KNOT_EOK) {
+		return result;
+	}
+
+	return sign_ctx_add_records(ctx, covered, orig_ttl, trim_labels);
+}
+
+int kr_check_signature(const knot_rdata_t *rrsig,
+                       const dnssec_key_t *key, const knot_rrset_t *covered,
+                       int trim_labels)
+{
+	if (!rrsig || !key || !dnssec_key_can_verify(key)) {
+		return kr_error(EINVAL);
+	}
+
+	int ret = 0;
+	dnssec_sign_ctx_t *sign_ctx = NULL;
+	dnssec_binary_t signature = {
+		.data = /*const-cast*/(uint8_t*)knot_rrsig_signature(rrsig),
+		.size = knot_rrsig_signature_len(rrsig),
+	};
+	if (!signature.data || !signature.size) {
+		ret = kr_error(EINVAL);
+		goto fail;
+	}
+
+	if (dnssec_sign_new(&sign_ctx, key) != 0) {
+		ret = kr_error(ENOMEM);
+		goto fail;
+	}
+
+	uint32_t orig_ttl = knot_rrsig_original_ttl(rrsig);
+
+	if (sign_ctx_add_data(sign_ctx, rrsig->data, covered, orig_ttl, trim_labels) != 0) {
+		ret = kr_error(ENOMEM);
+		goto fail;
+	}
+
+	ret = dnssec_sign_verify(sign_ctx,
+		#if KNOT_VERSION_MAJOR >= 3
+			false,
+		#endif
+			&signature);
+	if (ret != 0) {
+		ret = kr_error(EBADMSG);
+		goto fail;
+	}
+
+	ret = kr_ok();
+
+fail:
+	dnssec_sign_free(sign_ctx);
+	return ret;
+}
diff --git a/lib/dnssec/signature.h b/lib/dnssec/signature.h
new file mode 100644
index 0000000..9e71ad9
--- /dev/null
+++ b/lib/dnssec/signature.h
@@ -0,0 +1,29 @@
+/*  Copyright (C) 2015-2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#pragma once
+
+#include <libdnssec/key.h>
+#include <libknot/rrset.h>
+
+/**
+ * Performs referral authentication according to RFC4035 5.2, bullet 2
+ * @param ref Referral RRSet. Currently only DS can be used.
+ * @param key Already parsed key.
+ * @return    0 or error code.  In particular: DNSSEC_INVALID_DS_ALGORITHM
+ *            in case *all* DSs in ref use an unimplemented algorithm.
+ */
+int kr_authenticate_referral(const knot_rrset_t *ref, const dnssec_key_t *key);
+
+/**
+ * Check the signature of the supplied RRSet.
+ * @param rrsig       RRSet containing signatures.
+ * @param key         Key to be used to validate the signature.
+ * @param covered     The covered RRSet.
+ * @param trim_labels Number of the leftmost labels to be removed and replaced with '*.'.
+ * @return            0 if signature valid, error code else.
+ */
+int kr_check_signature(const knot_rdata_t *rrsig,
+                       const dnssec_key_t *key, const knot_rrset_t *covered,
+                       int trim_labels);
diff --git a/lib/dnssec/ta.c b/lib/dnssec/ta.c
new file mode 100644
index 0000000..b6a8cb0
--- /dev/null
+++ b/lib/dnssec/ta.c
@@ -0,0 +1,173 @@
+/*  Copyright (C) 2014-2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#include <contrib/cleanup.h>
+#include <libknot/descriptor.h>
+#include <libknot/rdataset.h>
+#include <libknot/rrset.h>
+#include <libknot/packet/wire.h>
+#include <libdnssec/key.h>
+#include <libdnssec/error.h>
+
+#include "lib/defines.h"
+#include "lib/dnssec.h"
+#include "lib/dnssec/ta.h"
+#include "lib/resolve.h"
+#include "lib/utils.h"
+
+knot_rrset_t *kr_ta_get(map_t *trust_anchors, const knot_dname_t *name)
+{
+	return map_get(trust_anchors, (const char *)name);
+}
+
+const knot_dname_t *kr_ta_get_longest_name(map_t *trust_anchors, const knot_dname_t *name)
+{
+	while(name) {
+		if (kr_ta_get(trust_anchors, name)) {
+			return name;
+		}
+		if (name[0] == '\0') {
+			break;
+		}
+		name = knot_wire_next_label(name, NULL);
+	}
+	return NULL;
+}
+
+/* @internal Create DS from DNSKEY, caller MUST free dst if successful. */
+static int dnskey2ds(dnssec_binary_t *dst, const knot_dname_t *owner, const uint8_t *rdata, uint16_t rdlen)
+{
+	dnssec_key_t *key = NULL;
+	int ret = dnssec_key_new(&key);
+	if (ret) goto cleanup;
+	/* Create DS from DNSKEY and reinsert */
+	const dnssec_binary_t key_data = { .size = rdlen, .data = (uint8_t *)rdata };
+	ret = dnssec_key_set_rdata(key, &key_data);
+	if (ret) goto cleanup;
+	/* Accept only keys with Zone and SEP flags that aren't revoked,
+	 * as a precaution.  RFC 5011 also utilizes these flags.
+	 * TODO: kr_dnssec_key_* names are confusing. */
+	const bool flags_ok = kr_dnssec_key_zsk(rdata) && !kr_dnssec_key_revoked(rdata);
+	if (!flags_ok) {
+		auto_free char *owner_str = kr_dname_text(owner);
+		kr_log_error("[ ta ] refusing to trust %s DNSKEY because of flags %d\n",
+			owner_str, dnssec_key_get_flags(key));
+		ret = kr_error(EILSEQ);
+		goto cleanup;
+	} else if (!kr_dnssec_key_ksk(rdata)) {
+		auto_free char *owner_str = kr_dname_text(owner);
+		int flags = dnssec_key_get_flags(key);
+		kr_log_info("[ ta ] warning: %s DNSKEY is missing the SEP bit; "
+			"flags %d instead of %d\n",
+			owner_str, flags, flags + 1/*a little ugly*/);
+	}
+	ret = dnssec_key_set_dname(key, owner);
+	if (ret) goto cleanup;
+	ret = dnssec_key_create_ds(key, DNSSEC_KEY_DIGEST_SHA256, dst);
+cleanup:
+	dnssec_key_free(key);
+	return kr_error(ret);
+}
+
+/* @internal Insert new TA to trust anchor set, rdata MUST be of DS type. */
+static int insert_ta(map_t *trust_anchors, const knot_dname_t *name,
+                     uint32_t ttl, const uint8_t *rdata, uint16_t rdlen)
+{
+	bool is_new_key = false;
+	knot_rrset_t *ta_rr = kr_ta_get(trust_anchors, name);
+	if (!ta_rr) {
+		ta_rr = knot_rrset_new(name, KNOT_RRTYPE_DS, KNOT_CLASS_IN, ttl, NULL);
+		is_new_key = true;
+	}
+	/* Merge-in new key data */
+	if (!ta_rr || (rdlen > 0 && knot_rrset_add_rdata(ta_rr, rdata, rdlen, NULL) != 0)) {
+		knot_rrset_free(ta_rr, NULL);
+		return kr_error(ENOMEM);
+	}
+	if (is_new_key) {
+		return map_set(trust_anchors, (const char *)name, ta_rr);
+	}
+	return kr_ok();
+}
+
+int kr_ta_add(map_t *trust_anchors, const knot_dname_t *name, uint16_t type,
+              uint32_t ttl, const uint8_t *rdata, uint16_t rdlen)
+{
+	if (!trust_anchors || !name) {
+		return kr_error(EINVAL);
+	}
+
+	/* DS/DNSEY types are accepted, for DNSKEY we
+	 * need to compute a DS digest. */
+	if (type == KNOT_RRTYPE_DS) {
+		return insert_ta(trust_anchors, name, ttl, rdata, rdlen);
+	} else if (type == KNOT_RRTYPE_DNSKEY) {
+		dnssec_binary_t ds_rdata = { 0, };
+		int ret = dnskey2ds(&ds_rdata, name, rdata, rdlen);
+		if (ret != 0) {
+			return ret;
+		}
+		ret = insert_ta(trust_anchors, name, ttl, ds_rdata.data, ds_rdata.size);
+		dnssec_binary_free(&ds_rdata);
+		return ret;
+	} else { /* Invalid type for TA */
+		return kr_error(EINVAL);
+	}
+}
+
+int kr_ta_covers(map_t *trust_anchors, const knot_dname_t *name)
+{
+	while(name) {
+		if (kr_ta_get(trust_anchors, name)) {
+			return true;
+		}
+		if (name[0] == '\0') {
+			return false;
+		}
+		name = knot_wire_next_label(name, NULL);
+	}
+	return false;
+}
+
+bool kr_ta_covers_qry(struct kr_context *ctx, const knot_dname_t *name,
+		      const uint16_t type)
+{
+	assert(ctx && name);
+	if (type == KNOT_RRTYPE_DS && name[0] != '\0') {
+		/* DS is parent-side record, so the parent name needs to be covered. */
+		name = knot_wire_next_label(name, NULL);
+		if (!name) {
+			assert(false);
+			return false;
+		}
+	}
+	return kr_ta_covers(&ctx->trust_anchors, name)
+		&& !kr_ta_covers(&ctx->negative_anchors, name);
+}
+
+/* Delete record data */
+static int del_record(const char *k, void *v, void *ext)
+{
+	knot_rrset_t *ta_rr = v;
+	if (ta_rr) {
+		knot_rrset_free(ta_rr, NULL);
+	}
+	return 0;
+}
+
+int kr_ta_del(map_t *trust_anchors, const knot_dname_t *name)
+{
+	knot_rrset_t *ta_rr = kr_ta_get(trust_anchors, name);
+	if (ta_rr) {
+		del_record(NULL, ta_rr, NULL);
+		map_del(trust_anchors, (const char *)name);
+	}
+	return kr_ok();
+}
+
+void kr_ta_clear(map_t *trust_anchors)
+{
+	map_walk(trust_anchors, del_record, NULL);
+	map_clear(trust_anchors);
+}
diff --git a/lib/dnssec/ta.h b/lib/dnssec/ta.h
new file mode 100644
index 0000000..f8fc93a
--- /dev/null
+++ b/lib/dnssec/ta.h
@@ -0,0 +1,75 @@
+/*  Copyright (C) 2015-2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#pragma once
+
+#include "lib/generic/map.h"
+#include <libknot/rrset.h>
+
+/**
+ * Find TA RRSet by name.
+ * @param  trust_anchors trust store
+ * @param  name          name of the TA
+ * @return non-empty RRSet or NULL
+ */
+KR_EXPORT
+knot_rrset_t *kr_ta_get(map_t *trust_anchors, const knot_dname_t *name);
+
+/**
+ * Add TA to trust store. DS or DNSKEY types are supported.
+ * @param  trust_anchors trust store
+ * @param  name          name of the TA
+ * @param  type          RR type of the TA (DS or DNSKEY)
+ * @param  ttl           
+ * @param  rdata         
+ * @param  rdlen         
+ * @return 0 or an error
+ */
+KR_EXPORT
+int kr_ta_add(map_t *trust_anchors, const knot_dname_t *name, uint16_t type,
+               uint32_t ttl, const uint8_t *rdata, uint16_t rdlen);
+
+/**
+ * Return true if the name is below/at any TA in the store.
+ * This can be useful to check if it's possible to validate a name beforehand.
+ * @param  trust_anchors trust store
+ * @param  name          name of the TA
+ * @return boolean
+ */
+KR_EXPORT KR_PURE
+int kr_ta_covers(map_t *trust_anchors, const knot_dname_t *name);
+
+struct kr_context;
+/**
+ * A wrapper around kr_ta_covers that is aware of negative TA and types.
+ */
+KR_EXPORT KR_PURE
+bool kr_ta_covers_qry(struct kr_context *ctx, const knot_dname_t *name,
+		      const uint16_t type);
+
+/**
+ * Remove TA from trust store.
+ * @param  trust_anchors trust store
+ * @param  name          name of the TA
+ * @return 0 or an error
+ */
+KR_EXPORT
+int kr_ta_del(map_t *trust_anchors, const knot_dname_t *name);
+
+/**
+ * Clear trust store.
+ * @param trust_anchors trust store
+ */
+KR_EXPORT
+void kr_ta_clear(map_t *trust_anchors);
+
+/**
+ * Return TA with the longest name that covers given name.
+ * @param trust_anchors trust store
+ * @param name name of the TA
+ * @return pointer to name or NULL.
+	   if not NULL, points inside the name parameter.
+ */
+KR_EXPORT
+const knot_dname_t *kr_ta_get_longest_name(map_t *trust_anchors, const knot_dname_t *name);
diff --git a/lib/generic/README.rst b/lib/generic/README.rst
new file mode 100644
index 0000000..e6a9994
--- /dev/null
+++ b/lib/generic/README.rst
@@ -0,0 +1,62 @@
+.. SPDX-License-Identifier: GPL-3.0-or-later
+
+Generics library
+----------------
+
+This small collection of "generics" was born out of frustration that I couldn't find no
+such thing for C. It's either bloated, has poor interface, null-checking is absent or
+doesn't allow custom allocation scheme. BSD-licensed (or compatible) code is allowed here,
+as long as it comes with a test case in `tests/test_generics.c`.
+
+* array_ - a set of simple macros to make working with dynamic arrays easier.
+* queue_ - a FIFO + LIFO queue.
+* map_ - a `Crit-bit tree`_ key-value map implementation (public domain) that comes with tests.
+* set_ - set abstraction implemented on top of ``map`` (unused now).
+* pack_ - length-prefixed list of objects (i.e. array-list).
+* lru_ - LRU-like hash table
+* trie_ - a trie-based key-value map, taken from knot-dns
+
+array
+~~~~~
+
+.. doxygenfile:: array.h
+   :project: libkres
+
+queue
+~~~~~
+
+.. doxygenfile:: queue.h
+   :project: libkres
+
+map
+~~~
+
+.. doxygenfile:: map.h
+   :project: libkres
+
+set
+~~~
+
+.. doxygenfile:: set.h
+   :project: libkres
+
+pack
+~~~~
+
+.. doxygenfile:: pack.h
+   :project: libkres
+
+lru
+~~~
+
+.. doxygenfile:: lru.h
+   :project: libkres
+
+trie
+~~~~
+
+.. doxygenfile:: trie.h
+   :project: libkres
+
+
+.. _`Crit-bit tree`: https://cr.yp.to/critbit.html 
diff --git a/lib/generic/array.h b/lib/generic/array.h
new file mode 100644
index 0000000..b20a802
--- /dev/null
+++ b/lib/generic/array.h
@@ -0,0 +1,154 @@
+/*  Copyright (C) 2015-2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+/**
+ *
+ * @file array.h
+ * @brief A set of simple macros to make working with dynamic arrays easier.
+ *
+ * @note The C has no generics, so it is implemented mostly using macros.
+ * Be aware of that, as direct usage of the macros in the evaluating macros
+ * may lead to different expectations:
+ *
+ * @code{.c}
+ *     MIN(array_push(arr, val), other)
+ * @endcode
+ *
+ * May evaluate the code twice, leading to unexpected behaviour.
+ * This is a price to pay for the absence of proper generics.
+ *
+ * # Example usage:
+ *
+ * @code{.c}
+ *      array_t(const char*) arr;
+ *      array_init(arr);
+ *
+ *      // Reserve memory in advance
+ *      if (array_reserve(arr, 2) < 0) {
+ *          return ENOMEM;
+ *      }
+ *
+ *      // Already reserved, cannot fail
+ *      array_push(arr, "princess");
+ *      array_push(arr, "leia");
+ *
+ *      // Not reserved, may fail
+ *      if (array_push(arr, "han") < 0) {
+ *          return ENOMEM;
+ *      }
+ *
+ *      // It does not hide what it really is
+ *      for (size_t i = 0; i < arr.len; ++i) {
+ *          printf("%s\n", arr.at[i]);
+ *      }
+ *
+ *      // Random delete
+ *      array_del(arr, 0);
+ * @endcode
+ * \addtogroup generics
+ * @{
+ */
+
+#pragma once
+#include <stdlib.h>
+
+/** Simplified Qt containers growth strategy. */
+static inline size_t array_next_count(size_t want)
+{
+	if (want < 2048) {
+		return (want < 20) ? want + 4 : want * 2;
+	} else {
+		return want + 2048;
+	}
+}
+
+/** @internal Incremental memory reservation */
+static inline int array_std_reserve(void *baton, void **mem, size_t elm_size, size_t want, size_t *have)
+{
+	if (*have >= want) {
+		return 0;
+	}
+	/* Simplified Qt containers growth strategy */
+	size_t next_size = array_next_count(want);
+	void *mem_new = realloc(*mem, next_size * elm_size);
+	if (mem_new != NULL) {
+		*mem = mem_new;
+		*have = next_size;
+		return 0;
+	}
+	return -1;
+}
+
+/** @internal Wrapper for stdlib free. */
+static inline void array_std_free(void *baton, void *p)
+{
+	free(p);
+}
+
+/** Declare an array structure. */
+#define array_t(type) struct {type * at; size_t len; size_t cap; }
+
+/** Zero-initialize the array. */
+#define array_init(array) ((array).at = NULL, (array).len = (array).cap = 0)
+
+/** Free and zero-initialize the array (plain malloc/free). */
+#define array_clear(array) \
+	array_clear_mm(array, array_std_free, NULL)
+
+/** Make the array empty and free pointed-to memory.
+ * Mempool usage: pass mm_free and a knot_mm_t* . */
+#define array_clear_mm(array, free, baton) \
+	(free)((baton), (array).at), array_init(array)
+
+/** Reserve capacity for at least n elements.
+ * @return 0 if success, <0 on failure */
+#define array_reserve(array, n) \
+	array_reserve_mm(array, n, array_std_reserve, NULL)
+
+/** Reserve capacity for at least n elements.
+ * Mempool usage: pass kr_memreserve and a knot_mm_t* .
+ * @return 0 if success, <0 on failure */
+#define array_reserve_mm(array, n, reserve, baton) \
+	(reserve)((baton), (void **) &(array).at, sizeof((array).at[0]), (n), &(array).cap)
+
+/**
+ * Push value at the end of the array, resize it if necessary.
+ * Mempool usage: pass kr_memreserve and a knot_mm_t* .
+ * @note May fail if the capacity is not reserved.
+ * @return element index on success, <0 on failure
+ */
+#define array_push_mm(array, val, reserve, baton) \
+	(int)((array).len < (array).cap ? ((array).at[(array).len] = val, (array).len++) \
+		: (array_reserve_mm(array, ((array).cap + 1), reserve, baton) < 0 ? -1 \
+			: ((array).at[(array).len] = val, (array).len++)))
+
+/**
+ * Push value at the end of the array, resize it if necessary (plain malloc/free).
+ * @note May fail if the capacity is not reserved.
+ * @return element index on success, <0 on failure
+ */
+#define array_push(array, val) \
+	array_push_mm(array, val, array_std_reserve, NULL)
+
+/**
+ * Pop value from the end of the array.
+ */
+#define array_pop(array) \
+ 	(array).len -= 1
+
+/**
+ * Remove value at given index.
+ * @return 0 on success, <0 on failure
+ */
+#define array_del(array, i) \
+	(int)((i) < (array).len ? ((array).len -= 1,(array).at[i] = (array).at[(array).len], 0) : -1)
+
+/**
+ * Return last element of the array.
+ * @warning Undefined if the array is empty.
+ */
+#define array_tail(array) \
+    (array).at[(array).len - 1]
+
+/** @} */
diff --git a/lib/generic/lru.c b/lib/generic/lru.c
new file mode 100644
index 0000000..dd2331d
--- /dev/null
+++ b/lib/generic/lru.c
@@ -0,0 +1,250 @@
+/*  Copyright (C) 2016-2018 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#include "lib/generic/lru.h"
+#include "contrib/murmurhash3/murmurhash3.h"
+#include "contrib/ucw/mempool.h"
+
+typedef struct lru_group lru_group_t;
+
+struct lru_item {
+	uint16_t key_len, val_len; /**< Two bytes should be enough for our purposes. */
+	char data[];
+	/**< Place for both key and value.
+	 *
+	 * We use "char" to satisfy the C99+ aliasing rules.
+	 * See C99 section 6.5 Expressions, paragraph 7.
+	 * Any type can be accessed through char-pointer,
+	 * so we can use a common struct definition
+	 * for all types being held.
+	 *
+	 * The value address is restricted by val_alignment.
+	 * Approach: require slightly larger sizes from the allocator
+	 * and shift value on the closest address with val_alignment.
+	 */
+};
+
+/** @brief Round the value up to a multiple of mul (a power of two). */
+static inline size_t round_power(size_t size, size_t mult)
+{
+	assert(__builtin_popcount(mult) == 1);
+	size_t res = ((size - 1) & ~(mult - 1)) + mult;
+	assert(__builtin_ctz(res) >= __builtin_ctz(mult));
+	assert(size <= res && res < size + mult);
+	return res;
+}
+
+/** @internal Compute the allocation size for an lru_item. */
+static uint item_size(const struct lru *lru, uint key_len, uint val_len)
+{
+	uint key_end = offsetof(struct lru_item, data) + key_len;
+	return key_end + (lru->val_alignment - 1) + val_len;
+	/*             ^^^ worst-case padding length
+	 * Well, we might compute the bound a bit more precisely,
+	 * as we know that lru_item will get alignment at least
+	 * some sizeof(void*) and we know all the lengths,
+	 * but let's not complicate it, as the gain would be small anyway. */
+}
+
+/** @internal Return pointer to value in an lru_item. */
+static void * item_val(const struct lru *lru, struct lru_item *it)
+{
+	size_t key_end = it->data + it->key_len - (char *)NULL;
+	size_t val_begin = round_power(key_end, lru->val_alignment);
+	return (char *)NULL + val_begin;
+}
+
+/** @internal Free each item. */
+KR_EXPORT void lru_free_items_impl(struct lru *lru)
+{
+	assert(lru);
+	for (size_t i = 0; i < (1 << (size_t)lru->log_groups); ++i) {
+		lru_group_t *g = &lru->groups[i];
+		for (int j = 0; j < LRU_ASSOC; ++j)
+			mm_free(lru->mm, g->items[j]);
+	}
+}
+
+/** @internal See lru_apply. */
+KR_EXPORT void lru_apply_impl(struct lru *lru, lru_apply_fun f, void *baton)
+{
+	bool ok = lru && f;
+	if (!ok) {
+		assert(false);
+		return;
+	}
+	for (size_t i = 0; i < (1 << (size_t)lru->log_groups); ++i) {
+		lru_group_t *g = &lru->groups[i];
+		for (uint j = 0; j < LRU_ASSOC; ++j) {
+			struct lru_item *it = g->items[j];
+			if (!it)
+				continue;
+			enum lru_apply_do ret =
+				f(it->data, it->key_len, item_val(lru, it), baton);
+			switch(ret) {
+			case LRU_APPLY_DO_EVICT: // evict
+				mm_free(lru->mm, it);
+				g->items[j] = NULL;
+				g->counts[j] = 0;
+				g->hashes[j] = 0;
+				break;
+			default:
+				assert(ret == LRU_APPLY_DO_NOTHING);
+			}
+		}
+	}
+}
+
+/** @internal See lru_create. */
+KR_EXPORT struct lru * lru_create_impl(uint max_slots, uint val_alignment,
+					knot_mm_t *mm_array, knot_mm_t *mm)
+{
+	assert(max_slots && __builtin_popcount(val_alignment) == 1);
+	if (!max_slots)
+		return NULL;
+	// let lru->log_groups = ceil(log2(max_slots / (float) assoc))
+	//   without trying for efficiency
+	uint group_count = (max_slots - 1) / LRU_ASSOC + 1;
+	uint log_groups = 0;
+	for (uint s = group_count - 1; s; s /= 2)
+		++log_groups;
+	group_count = 1 << log_groups;
+	assert(max_slots <= group_count * LRU_ASSOC && group_count * LRU_ASSOC < 2 * max_slots);
+
+	/* Get a sufficiently aligning mm_array if NULL is passed. */
+	if (!mm_array) {
+		static knot_mm_t mm_array_default = { 0 };
+		if (!mm_array_default.ctx)
+			mm_ctx_init_aligned(&mm_array_default, alignof(struct lru));
+		mm_array = &mm_array_default;
+	}
+	assert(mm_array->alloc && mm_array->alloc != (knot_mm_alloc_t)mp_alloc);
+
+	size_t size = offsetof(struct lru, groups[group_count]);
+	struct lru *lru = mm_alloc(mm_array, size);
+	if (unlikely(lru == NULL))
+		return NULL;
+	*lru = (struct lru){
+		.mm = mm,
+		.mm_array = mm_array,
+		.log_groups = log_groups,
+		.val_alignment = val_alignment,
+	};
+	// zeros are a good init
+	memset(lru->groups, 0, size - offsetof(struct lru, groups));
+	return lru;
+}
+
+/** @internal Decrement all counters within a group. */
+static void group_dec_counts(lru_group_t *g) {
+	g->counts[LRU_TRACKED] = LRU_TRACKED;
+	for (uint i = 0; i < LRU_TRACKED + 1; ++i)
+		if (likely(g->counts[i]))
+			--g->counts[i];
+}
+
+/** @internal Increment a counter within a group. */
+static void group_inc_count(lru_group_t *g, int i) {
+	if (likely(++(g->counts[i])))
+       		return;
+	g->counts[i] = -1;
+	// We could've decreased or halved all of them, but let's keep the max.
+}
+
+/** @internal Implementation of both getting and insertion.
+ * Note: val_len is only meaningful if do_insert.
+ *       *is_new is only meaningful when return value isn't NULL, contains
+ *	 true when returned lru entry has been allocated right now
+ *	 if return value is NULL, *is_new remains untouched.
+ */
+KR_EXPORT void * lru_get_impl(struct lru *lru, const char *key, uint key_len,
+			      uint val_len, bool do_insert, bool *is_new)
+{
+	bool ok = lru && (key || !key_len) && key_len <= UINT16_MAX
+		   && (!do_insert || val_len <= UINT16_MAX);
+	if (!ok) {
+		assert(false);
+		return NULL; // reasonable fallback when not debugging
+	}
+	bool is_new_entry = false;
+	// find the right group
+	uint32_t khash = hash(key, key_len);
+	uint16_t khash_top = khash >> 16;
+	lru_group_t *g = &lru->groups[khash & ((1 << lru->log_groups) - 1)];
+	struct lru_item *it = NULL;
+	uint i;
+	// scan the *stored* elements in the group
+	for (i = 0; i < LRU_ASSOC; ++i) {
+		if (g->hashes[i] == khash_top) {
+			it = g->items[i];
+			if (likely(it && it->key_len == key_len
+					&& (key_len == 0 || memcmp(it->data, key, key_len) == 0))) {
+				/* Found a key, but trying to insert a value larger than available
+				 * space in the allocated slot, so the entry must be resized to fit. */
+				if (unlikely(do_insert && val_len > it->val_len)) {
+					goto insert;
+				} else {
+					goto found; // to reduce huge nesting depth	
+				}
+			}
+		}
+	}
+	// key not found; first try an empty/counted-out place to insert
+	if (do_insert)
+		for (i = 0; i < LRU_ASSOC; ++i)
+			if (g->items[i] == NULL || g->counts[i] == 0)
+				goto insert;
+	// check if we track key's count at least
+	for (i = LRU_ASSOC; i < LRU_TRACKED; ++i) {
+		if (g->hashes[i] == khash_top) {
+			group_inc_count(g, i);
+			if (!do_insert)
+				return NULL;
+			// check if we trumped some stored key
+			for (uint j = 0; j < LRU_ASSOC; ++j)
+				if (unlikely(g->counts[i] > g->counts[j])) {
+					// evict key j, i.e. swap with i
+					--g->counts[i]; // we increment it below
+					SWAP(g->counts[i], g->counts[j]);
+					SWAP(g->hashes[i], g->hashes[j]);
+					i = j;
+					goto insert;
+				}
+			return NULL;
+		}
+	}
+	// not found at all: decrement all counts but only on every LRU_TRACKED occasion
+	if (g->counts[LRU_TRACKED])
+		--g->counts[LRU_TRACKED];
+	else
+		group_dec_counts(g);
+	return NULL;
+insert: // insert into position i (incl. key)
+	assert(i < LRU_ASSOC);
+	g->hashes[i] = khash_top;
+	it = g->items[i];
+	uint new_size = item_size(lru, key_len, val_len);
+	if (it == NULL || new_size != item_size(lru, it->key_len, it->val_len)) {
+		// (re)allocate
+		mm_free(lru->mm, it);
+		it = g->items[i] = mm_alloc(lru->mm, new_size);
+		if (it == NULL)
+			return NULL;
+	}
+	it->key_len = key_len;
+	it->val_len = val_len;
+	if (key_len > 0) {
+		memcpy(it->data, key, key_len);
+	}
+	memset(item_val(lru, it), 0, val_len); // clear the value
+	is_new_entry = true;
+found: // key and hash OK on g->items[i]; now update stamps
+	assert(i < LRU_ASSOC);
+	group_inc_count(g, i);
+	if (is_new) {
+		*is_new = is_new_entry;
+	}
+	return item_val(lru, g->items[i]);
+}
+
diff --git a/lib/generic/lru.h b/lib/generic/lru.h
new file mode 100644
index 0000000..a802b5b
--- /dev/null
+++ b/lib/generic/lru.h
@@ -0,0 +1,241 @@
+/*  Copyright (C) 2016-2018 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+/**
+ * @file lru.h
+ * @brief A lossy cache.
+ *
+ * @note The implementation tries to keep frequent keys and avoid others,
+ *  even if "used recently", so it may refuse to store it on lru_get_new().
+ *  It uses hashing to split the problem pseudo-randomly into smaller groups,
+ *  and within each it tries to approximate relative usage counts of several
+ *  most frequent keys/hashes.  This tracking is done for *more* keys than
+ *  those that are actually stored.
+ *
+ * Example usage:
+ * @code{.c}
+ * 	// Define new LRU type
+ * 	typedef lru_t(int) lru_int_t;
+ *
+ * 	// Create LRU
+ * 	lru_int_t *lru;
+ * 	lru_create(&lru, 5, NULL, NULL);
+ *
+ * 	// Insert some values
+ * 	int *pi = lru_get_new(lru, "luke", strlen("luke"), NULL);
+ * 	if (pi)
+ * 		*pi = 42;
+ * 	pi = lru_get_new(lru, "leia", strlen("leia"), NULL);
+ * 	if (pi)
+ * 		*pi = 24;
+ *
+ * 	// Retrieve values
+ * 	int *ret = lru_get_try(lru, "luke", strlen("luke"), NULL);
+ * 	if (!ret) printf("luke dropped out!\n");
+ * 	    else  printf("luke's number is %d\n", *ret);
+ *
+ * 	char *enemies[] = {"goro", "raiden", "subzero", "scorpion"};
+ * 	for (int i = 0; i < 4; ++i) {
+ * 		int *val = lru_get_new(lru, enemies[i], strlen(enemies[i]), NULL);
+ * 		if (val)
+ * 			*val = i;
+ * 	}
+ *
+ * 	// We're done
+ * 	lru_free(lru);
+ * @endcode
+ *
+ * \addtogroup generics
+ * @{
+ */
+
+#pragma once
+
+#include <assert.h>
+#include <stdalign.h>
+#include <stddef.h>
+#include <stdint.h>
+
+#include "contrib/ucw/lib.h"
+#include "lib/utils.h"
+#include "libknot/mm_ctx.h"
+
+/* ================================ Interface ================================ */
+
+/** @brief The type for LRU, parametrized by value type. */
+#define lru_t(type) \
+	union { \
+		type *pdata_t; /* only the *type* information is used */ \
+		struct lru lru; \
+	}
+
+/**
+ * @brief Allocate and initialize an LRU with default associativity.
+ *
+ * The real limit on the number of slots can be a bit larger but less than double.
+ *
+ * @param ptable pointer to a pointer to the LRU
+ * @param max_slots number of slots
+ * @param mm_ctx_array memory context to use for the huge array, NULL for default
+ * 	If you pass your own, it needs to produce CACHE_ALIGNED allocations (ubsan).
+ * @param mm_ctx memory context to use for individual key-value pairs, NULL for default
+ *
+ * @note The pointers to memory contexts need to remain valid
+ * 	during the whole life of the structure (or be NULL).
+ */
+/* Pragmas: C11 only standardizes alignof on type names, not on expressions.
+ * That's a GNU extension; in clang it's supported but may generate warnings.
+ * It seems hard to disable warnings that are only supported by some compilers. */
+#define lru_create(ptable, max_slots, mm_ctx_array, mm_ctx) do { \
+	(void)(((__typeof__((*(ptable))->pdata_t))0) == (void *)0); /* typecheck lru_t */ \
+	_Pragma("GCC diagnostic push") \
+	_Pragma("GCC diagnostic ignored \"-Wpragmas\"") \
+	_Pragma("GCC diagnostic ignored \"-Wunknown-pragmas\"") \
+	_Pragma("GCC diagnostic ignored \"-Wgnu-alignof-expression\"") \
+	*(ptable) = (__typeof__(*(ptable))) \
+		lru_create_impl((max_slots), alignof(*( (*(ptable))->pdata_t )), \
+				(mm_ctx_array), (mm_ctx)); \
+	_Pragma("GCC diagnostic pop") \
+	} while (false)
+
+/** @brief Free an LRU created by lru_create (it can be NULL). */
+#define lru_free(table) \
+	lru_free_impl(&(table)->lru)
+
+/** @brief Reset an LRU to the empty state (but preserve any settings). */
+#define lru_reset(table) \
+	lru_reset_impl(&(table)->lru)
+
+/**
+ * @brief Find key in the LRU and return pointer to the corresponding value.
+ *
+ * @param table pointer to LRU
+ * @param key_ lookup key
+ * @param len_ key length
+ * @return pointer to data or NULL if not found
+ */
+#define lru_get_try(table, key_, len_) \
+	(__typeof__((table)->pdata_t)) \
+		lru_get_impl(&(table)->lru, (key_), (len_), -1, false, NULL)
+
+/**
+ * @brief Return pointer to value, inserting if needed (zeroed).
+ *
+ * @param table pointer to LRU
+ * @param key_ lookup key
+ * @param len_ key lengthkeys
+ * @param is_new pointer to bool to store result of operation
+ *             (true if entry is newly added, false otherwise; can be NULL).
+ * @return pointer to data or NULL (can be even if memory could be allocated!)
+ */
+#define lru_get_new(table, key_, len_, is_new) \
+	(__typeof__((table)->pdata_t)) \
+		lru_get_impl(&(table)->lru, (key_), (len_), \
+		sizeof(*(table)->pdata_t), true, is_new)
+
+/**
+ * @brief Apply a function to every item in LRU.
+ *
+ * @param table pointer to LRU
+ * @param function enum lru_apply_do (*function)(const char *key, uint len, val_type *val, void *baton)
+ *        See enum lru_apply_do for the return type meanings.
+ * @param baton extra pointer passed to each function invocation
+ */
+#define lru_apply(table, function, baton) do { \
+	lru_apply_fun_g(fun_dummy, __typeof__(*(table)->pdata_t)) = 0; \
+	(void)(fun_dummy == (function)); /* produce a warning with incompatible function type */ \
+	lru_apply_impl(&(table)->lru, (lru_apply_fun)(function), (baton)); \
+	} while (false)
+
+/** @brief Possible actions to do with an element. */
+enum lru_apply_do {
+	LRU_APPLY_DO_NOTHING,
+	LRU_APPLY_DO_EVICT,
+	/* maybe more in future*/
+};
+
+/**
+ * @brief Return the real capacity - maximum number of keys holdable within.
+ *
+ * @param table pointer to LRU
+ */
+#define lru_capacity(table) lru_capacity_impl(&(table)->lru)
+
+
+
+/* ======================== Inlined part of implementation ======================== */
+/** @cond internal */
+
+#define lru_apply_fun_g(name, val_type) \
+	enum lru_apply_do (*(name))(const char *key, uint len, val_type *val, void *baton)
+typedef lru_apply_fun_g(lru_apply_fun, void);
+
+#if __GNUC__ >= 4
+	#define CACHE_ALIGNED __attribute__((aligned(64)))
+#else
+	#define CACHE_ALIGNED
+#endif
+
+struct lru;
+void lru_free_items_impl(struct lru *lru);
+struct lru * lru_create_impl(uint max_slots, uint val_alignment,
+			     knot_mm_t *mm_array, knot_mm_t *mm);
+void * lru_get_impl(struct lru *lru, const char *key, uint key_len,
+		    uint val_len, bool do_insert, bool *is_new);
+void lru_apply_impl(struct lru *lru, lru_apply_fun f, void *baton);
+
+struct lru_item;
+
+#if SIZE_MAX > (1 << 32)
+	/** @internal The number of keys stored within each group. */
+	#define LRU_ASSOC 3
+#else
+	#define LRU_ASSOC 4
+#endif
+/** @internal The number of hashes tracked within each group: 10-1 or 12-1. */
+#define LRU_TRACKED ((64 - sizeof(size_t) * LRU_ASSOC) / 4 - 1)
+
+struct lru_group {
+	uint16_t counts[LRU_TRACKED+1]; /*!< Occurrence counters; the last one is special. */
+	uint16_t hashes[LRU_TRACKED+1]; /*!< Top halves of hashes; the last one is unused. */
+	struct lru_item *items[LRU_ASSOC]; /*!< The full items. */
+} CACHE_ALIGNED;
+
+/* The sizes are chosen so lru_group just fits into a single x86 cache line. */
+static_assert(64 == sizeof(struct lru_group)
+		&& 64 == LRU_ASSOC * sizeof(void*) + (LRU_TRACKED+1) * 4,
+		"bad sizing for your sizeof(void*)");
+
+struct lru {
+	struct knot_mm *mm, /**< Memory context to use for keys. */
+		*mm_array; /**< Memory context to use for this structure itself. */
+	uint log_groups; /**< Logarithm of the number of LRU groups. */
+	uint val_alignment; /**< Alignment for the values. */
+	struct lru_group groups[] CACHE_ALIGNED; /**< The groups of items. */
+};
+
+/** @internal See lru_free. */
+static inline void lru_free_impl(struct lru *lru)
+{
+	if (!lru)
+		return;
+	lru_free_items_impl(lru);
+	mm_free(lru->mm_array, lru);
+}
+
+/** @internal See lru_reset. */
+static inline void lru_reset_impl(struct lru *lru)
+{
+	lru_free_items_impl(lru);
+	memset(lru->groups, 0, sizeof(lru->groups[0]) * (1 << lru->log_groups));
+}
+
+/** @internal See lru_capacity. */
+static inline uint lru_capacity_impl(struct lru *lru)
+{
+	assert(lru);
+	return (1 << lru->log_groups) * LRU_ASSOC;
+}
+
+/** @endcond */
+/** @} (addtogroup generics) */
diff --git a/lib/generic/map.c b/lib/generic/map.c
new file mode 100644
index 0000000..9fc3e34
--- /dev/null
+++ b/lib/generic/map.c
@@ -0,0 +1,355 @@
+/*
+ * critbit89 - A crit-bit tree implementation for strings in C89
+ * Written by Jonas Gehring <jonas@jgehring.net>
+ * Implemented key-value storing by Marek Vavrusa <marek.vavrusa@nic.cz>
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ *
+ * The code makes the assumption that malloc returns pointers aligned at at
+ * least a two-byte boundary. Since the C standard requires that malloc return
+ * pointers that can store any type, there are no commonly-used toolchains for
+ * which this assumption is false.
+ *
+ * See https://github.com/agl/critbit/blob/master/critbit.pdf for reference.
+ */
+
+#include <errno.h>
+#include <string.h>
+#include <stdlib.h>
+
+#include "map.h"
+#include "lib/utils.h"
+
+ /* Exports */
+#if defined _WIN32 || defined __CYGWIN__
+  #define EXPORT __attribute__ ((dllexport))
+#else
+  #define EXPORT __attribute__ ((visibility ("default")))
+#endif
+
+#ifdef _MSC_VER /* MSVC */
+ typedef unsigned __int8 uint8_t;
+ typedef unsigned __int32 uint32_t;
+ #ifdef _WIN64
+  typedef signed __int64 intptr_t;
+ #else
+  typedef _W64 signed int intptr_t;
+ #endif
+#else /* Not MSVC */
+ #include <stdint.h>
+#endif
+
+typedef struct {
+	void* value;
+	uint8_t key[];
+} cb_data_t;
+
+typedef struct {
+	void *child[2];
+	uint32_t byte;
+	uint8_t otherbits;
+} cb_node_t;
+
+/* Return true if ptr is internal node. */
+static inline int ref_is_internal(const uint8_t *p)
+{
+	return 1 & (intptr_t)p;
+}
+
+/* Get internal node. */
+static inline cb_node_t *ref_get_internal(uint8_t *p)
+{
+	return (cb_node_t *)(p - 1);
+}
+
+/* Static helper functions */
+static void cbt_traverse_delete(map_t *map, void *top)
+{
+	uint8_t *p = top;
+	if (ref_is_internal(p)) {
+		cb_node_t *q = ref_get_internal(p);
+		cbt_traverse_delete(map, q->child[0]);
+		cbt_traverse_delete(map, q->child[1]);
+		mm_free(map->pool, q);
+	} else {
+		mm_free(map->pool, p);
+	}
+}
+
+static int cbt_traverse_prefixed(void *top,
+	int (*callback)(const char *, void *, void *), void *baton)
+{
+	uint8_t *p = top;
+	cb_data_t *x = (cb_data_t *)top;
+
+	if (ref_is_internal(p)) {
+		cb_node_t *q = ref_get_internal(p);
+		int ret = 0;
+
+		ret = cbt_traverse_prefixed(q->child[0], callback, baton);
+		if (ret != 0) {
+			return ret;
+		}
+		ret = cbt_traverse_prefixed(q->child[1], callback, baton);
+		if (ret != 0) {
+			return ret;
+		}
+		return 0;
+	}
+
+	return (callback)((const char *)x->key, x->value, baton);
+}
+
+static cb_data_t *cbt_make_data(map_t *map, const uint8_t *str, size_t len, void *value)
+{
+	cb_data_t *x = mm_alloc(map->pool, sizeof(cb_data_t) + len);
+	if (x != NULL) {
+		x->value = value;
+		memcpy(x->key, str, len);
+	}
+	return x;
+}
+
+/*! Like map_contains, but also set the value, if passed and found. */
+static int cbt_get(map_t *map, const char *str, void **value)
+{
+	const uint8_t *ubytes = (void *)str;
+	const size_t ulen = strlen(str);
+	uint8_t *p = map->root;
+	cb_data_t *x = NULL;
+
+	if (p == NULL) {
+		return 0;
+	}
+
+	while (ref_is_internal(p)) {
+		cb_node_t *q = ref_get_internal(p);
+		uint8_t c = 0;
+		int direction;
+
+		if (q->byte < ulen) {
+			c = ubytes[q->byte];
+		}
+		direction = (1 + (q->otherbits | c)) >> 8;
+
+		p = q->child[direction];
+	}
+
+	x = (cb_data_t *)p;
+	if (strcmp(str, (const char *)x->key) == 0) {
+		if (value != NULL) {
+			*value = x->value;
+		}
+		return 1;
+	}
+
+	return 0;
+}
+
+/*! Returns non-zero if map contains str */
+EXPORT int map_contains(map_t *map, const char *str)
+{
+	return cbt_get(map, str, NULL);
+}
+
+EXPORT void *map_get(map_t *map, const char *str)
+{
+	void *v = NULL;
+	cbt_get(map, str, &v);
+	return v;
+}
+
+EXPORT int map_set(map_t *map, const char *str, void *val)
+{
+	const uint8_t *const ubytes = (void *)str;
+	const size_t ulen = strlen(str);
+	uint8_t *p = map->root;
+	uint8_t c = 0, *x = NULL;
+	uint32_t newbyte = 0;
+	uint32_t newotherbits = 0;
+	int direction = 0, newdirection = 0;
+	cb_node_t *newnode = NULL;
+	cb_data_t *data = NULL;
+	void **wherep = NULL;
+
+	if (p == NULL) {
+		map->root = cbt_make_data(map, (const uint8_t *)str, ulen + 1, val);
+		if (map->root == NULL) {
+			return ENOMEM;
+		}
+		return 0;
+	}
+
+	while (ref_is_internal(p)) {
+		cb_node_t *q = ref_get_internal(p);
+		c = 0;
+		if (q->byte < ulen) {
+			c = ubytes[q->byte];
+		}
+		direction = (1 + (q->otherbits | c)) >> 8;
+
+		p = q->child[direction];
+	}
+
+	data = (cb_data_t *)p;
+	for (newbyte = 0; newbyte < ulen; ++newbyte) {
+		if (data->key[newbyte] != ubytes[newbyte]) {
+			newotherbits = data->key[newbyte] ^ ubytes[newbyte];
+			goto different_byte_found;
+		}
+	}
+
+	if (data->key[newbyte] != 0) {
+		newotherbits = data->key[newbyte];
+		goto different_byte_found;
+	}
+	data->value = val;
+	return 1;
+
+different_byte_found:
+	newotherbits |= newotherbits >> 1;
+	newotherbits |= newotherbits >> 2;
+	newotherbits |= newotherbits >> 4;
+	newotherbits = (newotherbits & ~(newotherbits >> 1)) ^ 255;
+	c = data->key[newbyte];
+	newdirection = (1 + (newotherbits | c)) >> 8;
+
+	newnode = mm_alloc(map->pool, sizeof(cb_node_t));
+	if (newnode == NULL) {
+		return ENOMEM;
+	}
+
+	x = (uint8_t *)cbt_make_data(map, ubytes, ulen + 1, val);
+	if (x == NULL) {
+		mm_free(map->pool, newnode);
+		return ENOMEM;
+	}
+
+	newnode->byte = newbyte;
+	newnode->otherbits = newotherbits;
+	newnode->child[1 - newdirection] = x;
+
+	/* Insert into map */
+	wherep = &map->root;
+	for (;;) {
+		cb_node_t *q;
+		p = *wherep;
+		if (!ref_is_internal(p)) {
+			break;
+		}
+
+		q = ref_get_internal(p);
+		if (q->byte > newbyte) {
+			break;
+		}
+		if (q->byte == newbyte && q->otherbits > newotherbits) {
+			break;
+		}
+
+		c = 0;
+		if (q->byte < ulen) {
+			c = ubytes[q->byte];
+		}
+		direction = (1 + (q->otherbits | c)) >> 8;
+		wherep = q->child + direction;
+	}
+
+	newnode->child[newdirection] = *wherep;
+	*wherep = (void *)(1 + (char *)newnode);
+	return 0;
+}
+
+/*! Deletes str from the map, returns 0 on success */
+EXPORT int map_del(map_t *map, const char *str)
+{
+	const uint8_t *ubytes = (void *)str;
+	const size_t ulen = strlen(str);
+	uint8_t *p = map->root;
+	void **wherep = NULL, **whereq = NULL;
+	cb_node_t *q = NULL;
+	cb_data_t *data = NULL;
+	int direction = 0;
+
+	if (map->root == NULL) {
+		return 1;
+	}
+	wherep = &map->root;
+
+	while (ref_is_internal(p)) {
+		uint8_t c = 0;
+		whereq = wherep;
+		q = ref_get_internal(p);
+
+		if (q->byte < ulen) {
+			c = ubytes[q->byte];
+		}
+		direction = (1 + (q->otherbits | c)) >> 8;
+		wherep = q->child + direction;
+		p = *wherep;
+	}
+
+	data = (cb_data_t *)p;
+	if (strcmp(str, (const char *)data->key) != 0) {
+		return 1;
+	}
+	mm_free(map->pool, p);
+
+	if (!whereq) {
+		map->root = NULL;
+		return 0;
+	}
+
+	*whereq = q->child[1 - direction];
+	mm_free(map->pool, q);
+	return 0;
+}
+
+/*! Clears the given map */
+EXPORT void map_clear(map_t *map)
+{
+	if (map->root) {
+		cbt_traverse_delete(map, map->root);
+	}
+	map->root = NULL;
+}
+
+/*! Calls callback for all strings in map with the given prefix */
+EXPORT int map_walk_prefixed(map_t *map, const char *prefix,
+	int (*callback)(const char *, void *, void *), void *baton)
+{
+	if (!map) {
+		return 0;
+	}
+
+	const uint8_t *ubytes = (void *)prefix;
+	const size_t ulen = strlen(prefix);
+	uint8_t *p = map->root;
+	uint8_t *top = p;
+	cb_data_t *data = NULL;
+
+	if (p == NULL) {
+		return 0;
+	}
+
+	while (ref_is_internal(p)) {
+		cb_node_t *q = ref_get_internal(p);
+		uint8_t c = 0;
+		int direction;
+
+		if (q->byte < ulen) {
+			c = ubytes[q->byte];
+		}
+		direction = (1 + (q->otherbits | c)) >> 8;
+
+		p = q->child[direction];
+		if (q->byte < ulen) {
+			top = p;
+		}
+	}
+
+	data = (cb_data_t *)p;
+	if (strlen((const char *)data->key) < ulen || memcmp(data->key, prefix, ulen) != 0) {
+		return 0; /* No strings match */
+	}
+
+	return cbt_traverse_prefixed(top, callback, baton);
+}
diff --git a/lib/generic/map.h b/lib/generic/map.h
new file mode 100644
index 0000000..cec9d39
--- /dev/null
+++ b/lib/generic/map.h
@@ -0,0 +1,116 @@
+/*
+ * critbit89 - A crit-bit map implementation for strings in C89
+ * Written by Jonas Gehring <jonas@jgehring.net>
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+/**
+ * @file map.h
+ * @brief A Crit-bit tree key-value map implementation.
+ *
+ * @warning If the user provides a custom allocator, it must return addresses aligned to 2B boundary.
+ *
+ * # Example usage:
+ *
+ * @code{.c}
+ *      map_t map = map_make(NULL);
+ *
+ *      // Custom allocator (optional)
+ *      map.malloc = &mymalloc;
+ *      map.baton  = &mymalloc_context;
+ *
+ *      // Insert k-v pairs
+ *      int values = { 42, 53, 64 };
+ *      if (map_set(&map, "princess", &values[0]) != 0 ||
+ *          map_set(&map, "prince", &values[1])   != 0 ||
+ *          map_set(&map, "leia", &values[2])     != 0) {
+ *          fail();
+ *      }
+ *
+ *      // Test membership
+ *      if (map_contains(&map, "leia")) {
+ *          success();
+ *      }
+ *
+ *      // Prefix search
+ *      int i = 0;
+ *      int count(const char *k, void *v, void *ext) { (*(int *)ext)++; return 0; }
+ *      if (map_walk_prefixed(map, "princ", count, &i) == 0) {
+ *          printf("%d matches\n", i);
+ *      }
+ *
+ *      // Delete
+ *      if (map_del(&map, "badkey") != 0) {
+ *          fail(); // No such key
+ *      }
+ *
+ *      // Clear the map
+ *      map_clear(&map);
+ * @endcode
+ *
+ * \addtogroup generics
+ * @{
+ */
+
+#pragma once
+
+#include <stddef.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct knot_mm; /* avoid the unnecessary include */
+
+/** Main data structure */
+typedef struct {
+	void *root;
+	struct knot_mm *pool;
+} map_t;
+
+/** Creates an new empty critbit map.  Pass NULL for malloc+free. */
+static inline map_t map_make(struct knot_mm *pool)
+{
+	return (map_t){ .root = NULL, .pool = pool };
+}
+
+/** Returns non-zero if map contains str */
+int map_contains(map_t *map, const char *str);
+
+/** Returns value if map contains str.  Note: NULL may mean two different things. */
+void *map_get(map_t *map, const char *str);
+
+/** Inserts str into map.  Returns 0 if new, 1 if replaced, or ENOMEM. */
+int map_set(map_t *map, const char *str, void *val);
+
+/** Deletes str from the map, returns 0 on suceess */
+int map_del(map_t *map, const char *str);
+
+/** Clears the given map */
+void map_clear(map_t *map);
+
+/**
+ * Calls callback for all strings in map
+ * See @fn map_walk_prefixed() for documentation on parameters.
+ */
+#define map_walk(map, callback, baton) \
+	map_walk_prefixed((map), "", (callback), (baton))
+
+/**
+ * Calls callback for all strings in map with the given prefix.
+ * Returns value immediately if a callback returns nonzero.
+ *
+ * @param map
+ * @param prefix   required string prefix (empty => all strings)
+ * @param callback callback parameters are (key, value, baton)
+ * @param baton    passed uservalue
+ */
+int map_walk_prefixed(map_t *map, const char *prefix,
+	int (*callback)(const char *, void *, void *), void *baton);
+
+
+#ifdef __cplusplus
+}
+#endif
+
+/** @} */
diff --git a/lib/generic/map.spdx b/lib/generic/map.spdx
new file mode 100644
index 0000000..cc39886
--- /dev/null
+++ b/lib/generic/map.spdx
@@ -0,0 +1,10 @@
+SPDXVersion: SPDX-2.1
+DataLicense: CC0-1.0
+SPDXID: SPDXRef-DOCUMENT
+DocumentName: map
+DocumentNamespace: http://spdx.org/spdxdocs/spdx-v2.1-d9b4db4c-062f-4add-89b6-f603224f5a2c
+
+PackageName: critbit89
+PackageDownloadLocation: git+https://github.com/jgehring/critbit89.git@4f7e1d2a5f4794e0d08cb408346973fb1e39489c#critbit.c
+PackageOriginator: Person: Jonas Gehring (jonas@jgehring.net)
+PackageLicenseDeclared: CC0-1.0
diff --git a/lib/generic/pack.h b/lib/generic/pack.h
new file mode 100644
index 0000000..463bb51
--- /dev/null
+++ b/lib/generic/pack.h
@@ -0,0 +1,237 @@
+/*  Copyright (C) 2015-2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+/**
+ * @file pack.h
+ * @brief A length-prefixed list of objects, also an array list.
+ * 
+ * Each object is prefixed by item length, unlike array this structure 
+ * permits variable-length data. It is also equivallent to forward-only list
+ * backed by an array.
+ *
+ * @note Maximum object size is 2^16 bytes, see  ::pack_objlen_t
+ * @todo If some mistake happens somewhere, the access may end up in an infinite loop.
+ *       (equality comparison on pointers)
+ *
+ * # Example usage:
+ *
+ * @code{.c}
+ *      pack_t pack;
+ *      pack_init(pack);
+ *
+ *      // Reserve 2 objects, 6 bytes total
+ *      pack_reserve(pack, 2, 4 + 2);
+ * 
+ *      // Push 2 objects
+ *      pack_obj_push(pack, U8("jedi"), 4)
+ *      pack_obj_push(pack, U8("\xbe\xef"), 2);
+ *
+ *      // Iterate length-value pairs
+ *      uint8_t *it = pack_head(pack);
+ *      while (it != pack_tail(pack)) {
+ *          uint8_t *val = pack_obj_val(it);
+ *          it = pack_obj_next(it);
+ *      }
+ *
+ *      // Remove object
+ *      pack_obj_del(pack, U8("jedi"), 4);
+ *
+ *      pack_clear(pack);
+ * @endcode
+ *
+ * \addtogroup generics
+ * @{
+ */
+
+#pragma once
+
+#include <stdint.h>
+#include <string.h>
+#include "array.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/** Packed object length type. */
+typedef uint16_t pack_objlen_t;
+
+/** Pack is defined as an array of bytes */
+typedef array_t(uint8_t) pack_t;
+
+/** Zero-initialize the pack. */
+#define pack_init(pack) \
+	array_init(pack)
+
+/** Make the pack empty and free pointed-to memory (plain malloc/free). */
+#define pack_clear(pack) \
+	array_clear(pack)
+
+/** Make the pack empty and free pointed-to memory.
+ * Mempool usage: pass mm_free and a knot_mm_t* . */
+#define pack_clear_mm(pack, free, baton) \
+	array_clear_mm((pack), (free), (baton))
+
+/** Reserve space for *additional* objects in the pack (plain malloc/free).
+ * @return 0 if success, <0 on failure */
+#define pack_reserve(pack, objs_count, objs_len) \
+	pack_reserve_mm((pack), (objs_count), (objs_len), array_std_reserve, NULL)
+
+/** Reserve space for *additional* objects in the pack.
+ * Mempool usage: pass kr_memreserve and a knot_mm_t* .
+ * @return 0 if success, <0 on failure */
+#define pack_reserve_mm(pack, objs_count, objs_len, reserve, baton) \
+	array_reserve_mm((pack), (pack).len + (sizeof(pack_objlen_t)*(objs_count) + (objs_len)), (reserve), (baton))
+
+/** Return pointer to first packed object.
+ *
+ * Recommended way to iterate:
+ *   for (uint8_t *it = pack_head(pack); it != pack_tail(pack); it = pack_obj_next(it))
+ */
+#define pack_head(pack) \
+	((pack).len > 0 ? &((pack).at[0]) : NULL)
+
+/** Return pack end pointer. */
+#define pack_tail(pack) \
+	((pack).len > 0 ? &((pack).at[(pack).len]) : NULL)
+
+/** Return packed object length. */
+static inline pack_objlen_t pack_obj_len(uint8_t *it)
+{
+	pack_objlen_t len = 0;
+	if (it != NULL)
+		memcpy(&len, it, sizeof(len));
+	return len;
+}
+
+/** Return packed object value. */
+static inline uint8_t *pack_obj_val(uint8_t *it)
+{
+	if (it == NULL) {
+		assert(it);
+		return NULL;
+	}
+	return it + sizeof(pack_objlen_t);
+}
+
+/** Return pointer to next packed object. */
+static inline uint8_t *pack_obj_next(uint8_t *it)
+{
+	if (it == NULL) {
+		assert(it);
+		return NULL;
+	}
+	return pack_obj_val(it) + pack_obj_len(it);
+}
+
+/** Return pointer to the last packed object. */
+static inline uint8_t *pack_last(pack_t pack)
+{
+	if (pack.len == 0) {
+		return NULL;
+	}
+	uint8_t *it = pack_head(pack);
+	uint8_t *tail = pack_tail(pack);
+	while (true) {
+		uint8_t *next = pack_obj_next(it);
+		if (next == tail) {
+			return it;
+		}
+		it = next;
+	}
+}
+
+/** Push object to the end of the pack
+  * @return 0 on success, negative number on failure
+  */
+static inline int pack_obj_push(pack_t *pack, const uint8_t *obj, pack_objlen_t len)
+{
+	if (pack == NULL || obj == NULL) {
+		assert(false);
+		return kr_error(EINVAL);
+	}
+	size_t packed_len = len + sizeof(len);
+	if (pack->len + packed_len > pack->cap) {
+		return kr_error(ENOSPC);
+	}
+
+	uint8_t *endp = pack->at + pack->len;
+	memcpy(endp, (char *)&len, sizeof(len));
+	memcpy(endp + sizeof(len), obj, len);
+	pack->len += packed_len;
+	return 0;
+}
+
+/** Returns a pointer to packed object.
+  * @return pointer to packed object or NULL
+  */
+static inline uint8_t *pack_obj_find(pack_t *pack, const uint8_t *obj, pack_objlen_t len)
+{
+		if (pack == NULL || obj == NULL) {
+			assert(obj != NULL);
+			return NULL;
+		}
+		uint8_t *endp = pack_tail(*pack);
+		uint8_t *it = pack_head(*pack);
+		while (it != endp) {
+			uint8_t *val = pack_obj_val(it);
+			if (pack_obj_len(it) == len && memcmp(obj, val, len) == 0) {
+				return it;
+			}
+			it = pack_obj_next(it);
+		}
+		return NULL;
+}
+
+/** Delete object from the pack
+  * @return 0 on success, negative number on failure
+  */
+static inline int pack_obj_del(pack_t *pack, const uint8_t *obj, pack_objlen_t len)
+{
+	if (pack == NULL || obj == NULL) {
+		assert(obj != NULL);
+		return kr_error(EINVAL);
+	}
+	uint8_t *endp = pack_tail(*pack);
+	uint8_t *it = pack_obj_find(pack, obj, len);
+	if (it) {
+		size_t packed_len = len + sizeof(len);
+		memmove(it, it + packed_len, endp - it - packed_len);
+		pack->len -= packed_len;
+		return 0;
+	}
+	return -1;
+}
+
+/** Clone a pack, replacing destination pack; (*dst == NULL) is valid input.
+ * @return kr_error(ENOMEM) on allocation failure. */
+static inline int pack_clone(pack_t **dst, const pack_t *src, knot_mm_t *pool)
+{
+	if (!dst || !src) {
+		assert(false);
+		return kr_error(EINVAL);
+	}
+	/* Get a valid pack_t. */
+	if (!*dst) {
+		*dst = mm_alloc(pool, sizeof(pack_t));
+		if (!*dst) return kr_error(ENOMEM);
+		pack_init(**dst);
+		/* Clone data only if needed */
+		if (src->len == 0) return kr_ok();
+	}
+	/* Replace the contents of the pack_t. */
+	int ret = array_reserve_mm(**dst, src->len, kr_memreserve, pool);
+	if (ret < 0) {
+		return kr_error(ENOMEM);
+	}
+	memcpy((*dst)->at, src->at, src->len);
+	(*dst)->len = src->len;
+	return kr_ok();
+}
+
+#ifdef __cplusplus
+}
+#endif
+
+/** @} */
diff --git a/lib/generic/queue.c b/lib/generic/queue.c
new file mode 100644
index 0000000..f46050f
--- /dev/null
+++ b/lib/generic/queue.c
@@ -0,0 +1,112 @@
+/*  Copyright (C) 2018 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#include "lib/generic/queue.h"
+#include <string.h>
+
+void queue_init_impl(struct queue *q, size_t item_size)
+{
+	q->len = 0;
+	q->item_size = item_size;
+	q->head = q->tail = NULL;
+	/* Take 128 B (two x86 cache lines), except a small margin
+	 * that the allocator can use for its overhead.
+	 * Normally (64-bit pointers) this means 16 B header + 13*8 B data. */
+	q->chunk_cap = (128 - offsetof(struct queue_chunk, data)
+			- sizeof(size_t)
+			) / item_size;
+	if (!q->chunk_cap) q->chunk_cap = 1; /* item_size big enough by itself */
+}
+
+void queue_deinit_impl(struct queue *q)
+{
+	assert(q);
+	struct queue_chunk *p = q->head;
+	while (p != NULL) {
+		struct queue_chunk *pf = p;
+		p = p->next;
+		free(pf);
+	}
+#ifndef NDEBUG
+	memset(q, 0, sizeof(*q));
+#endif
+}
+
+static struct queue_chunk * queue_chunk_new(const struct queue *q)
+{
+	struct queue_chunk *c = malloc(offsetof(struct queue_chunk, data)
+					+ q->chunk_cap * q->item_size);
+	if (unlikely(!c)) abort(); // simplify stuff
+	memset(c, 0, offsetof(struct queue_chunk, data));
+	c->cap = q->chunk_cap;
+	/* ->begin and ->end are zero, i.e. we optimize for _push
+	 * and not _push_head, by default. */
+	return c;
+}
+
+/* Return pointer to the space for the new element. */
+void * queue_push_impl(struct queue *q)
+{
+	assert(q);
+	struct queue_chunk *t = q->tail; // shorthand
+	if (unlikely(!t)) {
+		assert(!q->head && !q->len);
+		q->head = q->tail = t = queue_chunk_new(q);
+	} else
+	if (t->end == t->cap) {
+		if (t->begin * 2 >= t->cap) {
+			/* Utilization is below 50%, so let's shift (no overlap). */
+			memcpy(t->data, t->data + t->begin * q->item_size,
+				(t->end - t->begin) * q->item_size);
+			t->end -= t->begin;
+			t->begin = 0;
+		} else {
+			/* Let's grow the tail by another chunk. */
+			assert(!t->next);
+			t->next = queue_chunk_new(q);
+			t = q->tail = t->next;
+		}
+	}
+	assert(t->end < t->cap);
+	++(q->len);
+	++(t->end);
+	return t->data + q->item_size * (t->end - 1);
+}
+
+/* Return pointer to the space for the new element. */
+void * queue_push_head_impl(struct queue *q)
+{
+	/* When we have choice, we optimize for further _push_head,
+	 * i.e. when shifting or allocating a chunk,
+	 * we store items on the tail-end of the chunk. */
+	assert(q);
+	struct queue_chunk *h = q->head; // shorthand
+	if (unlikely(!h)) {
+		assert(!q->tail && !q->len);
+		h = q->head = q->tail = queue_chunk_new(q);
+		h->begin = h->end = h->cap;
+	} else
+	if (h->begin == 0) {
+		if (h->end * 2 <= h->cap) {
+			/* Utilization is below 50%, so let's shift (no overlap).
+			 * Computations here are simplified due to h->begin == 0. */
+			const int cnt = h->end;
+			memcpy(h->data + (h->cap - cnt) * q->item_size, h->data,
+				cnt * q->item_size);
+			h->begin = h->cap - cnt;
+			h->end = h->cap;
+		} else {
+			/* Let's grow the head by another chunk. */
+			h = queue_chunk_new(q);
+			h->next = q->head;
+			q->head = h;
+			h->begin = h->end = h->cap;
+		}
+	}
+	assert(h->begin > 0);
+	--(h->begin);
+	++(q->len);
+	return h->data + q->item_size * h->begin;
+}
+
diff --git a/lib/generic/queue.h b/lib/generic/queue.h
new file mode 100644
index 0000000..418e19c
--- /dev/null
+++ b/lib/generic/queue.h
@@ -0,0 +1,252 @@
+/*  Copyright (C) 2018 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+/**
+ * @file queue.h
+ * @brief A queue, usable for FIFO and LIFO simultaneously.
+ *
+ * Both the head and tail of the queue can be accessed and pushed to,
+ * but only the head can be popped from.
+ *
+ * @note The implementation uses a singly linked list of blocks ("chunks")
+ * where each block stores an array of values (for better efficiency).
+ *
+ * Example usage:
+ * @code{.c}
+	// define new queue type, and init a new queue instance
+	typedef queue_t(int) queue_int_t;
+	queue_int_t q;
+	queue_init(q);
+	// do some operations
+	queue_push(q, 1);
+	queue_push(q, 2);
+	queue_push(q, 3);
+	queue_push(q, 4);
+	queue_pop(q);
+	assert(queue_head(q) == 2);
+	assert(queue_tail(q) == 4);
+
+	// you may iterate
+	typedef queue_it_t(int) queue_it_int_t;
+	for (queue_it_int_t it = queue_it_begin(q); !queue_it_finished(it);
+	     queue_it_next(it)) {
+		++queue_it_val(it);
+	}
+	assert(queue_tail(q) == 5);
+
+	queue_push_head(q, 0);
+	++queue_tail(q);
+	assert(queue_tail(q) == 6);
+	// free it up
+	queue_deinit(q);
+
+	// you may use dynamic allocation for the type itself
+	queue_int_t *qm = malloc(sizeof(queue_int_t));
+	queue_init(*qm);
+	queue_deinit(*qm);
+	free(qm);
+ * @endcode
+ *
+ * \addtogroup generics
+ * @{
+ */
+
+#pragma once
+
+#include "lib/defines.h"
+#include "contrib/ucw/lib.h"
+#include <assert.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+/** @brief The type for queue, parametrized by value type. */
+#define queue_t(type) \
+	union { \
+		type *pdata_t; /* only the *type* information is used */ \
+		struct queue queue; \
+	}
+
+/** @brief Initialize a queue.  You can malloc() it the usual way. */
+#define queue_init(q) do { \
+	(void)(((__typeof__(((q).pdata_t)))0) == (void *)0); /* typecheck queue_t */ \
+	queue_init_impl(&(q).queue, sizeof(*(q).pdata_t)); \
+	} while (false)
+
+/** @brief De-initialize a queue: make it invalid and free any inner allocations. */
+#define queue_deinit(q) \
+	queue_deinit_impl(&(q).queue)
+
+/** @brief Push data to queue's tail.  (Type-safe version; use _impl() otherwise.) */
+#define queue_push(q, data) \
+	*((__typeof__((q).pdata_t)) queue_push_impl(&(q).queue)) = data
+
+/** @brief Push data to queue's head.  (Type-safe version; use _impl() otherwise.) */
+#define queue_push_head(q, data) \
+	*((__typeof__((q).pdata_t)) queue_push_head_impl(&(q).queue)) = data
+
+/** @brief Remove the element at the head.
+ * The queue must not be empty. */
+#define queue_pop(q) \
+	queue_pop_impl(&(q).queue)
+
+/** @brief Return a "reference" to the element at the head (it's an L-value).
+ * The queue must not be empty. */
+#define queue_head(q) \
+	( *(__typeof__((q).pdata_t)) queue_head_impl(&(q).queue) )
+
+/** @brief Return a "reference" to the element at the tail (it's an L-value).
+ * The queue must not be empty. */
+#define queue_tail(q) \
+	( *(__typeof__((q).pdata_t)) queue_tail_impl(&(q).queue) )
+
+/** @brief Return the number of elements in the queue (very efficient). */
+#define queue_len(q) \
+	((const size_t)(q).queue.len)
+
+
+/** @brief Type for queue iterator, parametrized by value type.
+ * It's a simple structure that owns no other resources.
+ * You may NOT use it after doing any push or pop (without _begin again). */
+#define queue_it_t(type) \
+	union { \
+		type *pdata_t; /* only the *type* information is used */ \
+		struct queue_it iter; \
+	}
+
+/** @brief Initialize a queue iterator at the head of the queue.
+ * If you use this in assignment (instead of initialization),
+ * you will unfortunately need to add corresponding type-cast in front.
+ * Beware: there's no type-check between queue and iterator! */
+#define queue_it_begin(q) \
+	{ .iter = queue_it_begin_impl(&(q).queue) }
+
+/** @brief Return a "reference" to the current element (it's an L-value) . */
+#define queue_it_val(it) \
+	( *(__typeof__((it).pdata_t)) queue_it_val_impl(&(it).iter) )
+
+/** @brief Test if the iterator has gone past the last element.
+ * If it has, you may not use _val or _next. */
+#define queue_it_finished(it) \
+	queue_it_finished_impl(&(it).iter)
+
+/** @brief Advance the iterator to the next element. */
+#define queue_it_next(it) \
+	queue_it_next_impl(&(it).iter)
+
+
+
+/* ====================== Internal for the implementation ================== */
+/** @cond internal */
+
+struct queue;
+/* Non-inline functions are exported to be usable from daemon. */
+KR_EXPORT void queue_init_impl(struct queue *q, size_t item_size);
+KR_EXPORT void queue_deinit_impl(struct queue *q);
+KR_EXPORT void * queue_push_impl(struct queue *q);
+KR_EXPORT void * queue_push_head_impl(struct queue *q);
+
+struct queue_chunk;
+struct queue {
+	size_t len; /**< the current number of items in queue */
+	uint16_t chunk_cap; /**< max. number of items in each chunk */
+	uint16_t item_size; /**< sizeof() each item */
+	struct queue_chunk *head, *tail; /*< first and last chunk (or NULLs) */
+};
+
+struct queue_chunk {
+	struct queue_chunk *next; /*< *head -> ... -> *tail; each is non-empty */
+	int16_t begin, end, cap, pad_; /*< indices: zero is closest to head */
+	/*< We could fit into uint8_t for example, but the choice of (3+1)*2 bytes
+	 * is a compromise between wasting space and getting a good alignment.
+	 * In particular, queue_t(type*) will store the pointers on addresses
+	 * aligned to the pointer size, on both 64-bit and 32-bit platforms.
+	 */
+	char data[];
+	/**< The item data.  We use "char" to satisfy the C99+ aliasing rules.
+	 * See C99 section 6.5 Expressions, paragraph 7.
+	 * Any type can be accessed through char-pointer,
+	 * so we can use a common struct definition
+	 * for all types being held.
+	 */
+};
+
+static inline void * queue_head_impl(const struct queue *q)
+{
+	assert(q);
+	struct queue_chunk *h = q->head;
+	assert(h && h->end > h->begin);
+	return h->data + h->begin * q->item_size;
+}
+
+static inline void * queue_tail_impl(const struct queue *q)
+{
+	assert(q);
+	struct queue_chunk *t = q->tail;
+	assert(t && t->end > t->begin);
+	return t->data + (t->end - 1) * q->item_size;
+}
+
+static inline void queue_pop_impl(struct queue *q)
+{
+	assert(q);
+	struct queue_chunk *h = q->head;
+	assert(h && h->end > h->begin);
+	if (h->end - h->begin == 1) {
+		/* removing the last element in the chunk */
+		assert((q->len == 1) == (q->head == q->tail));
+		if (q->len == 1) {
+			q->tail = NULL;
+			assert(!h->next);
+		} else {
+			assert(h->next);
+		}
+		q->head = h->next;
+		free(h);
+	} else {
+		++(h->begin);
+	}
+	--(q->len);
+}
+
+
+struct queue_it {
+	struct queue_chunk *chunk;
+	int16_t pos, item_size;
+};
+
+static inline struct queue_it queue_it_begin_impl(struct queue *q)
+{
+	assert(q);
+	return (struct queue_it){
+		.chunk = q->head,
+		.pos = q->head ? q->head->begin : -1,
+		.item_size = q->item_size,
+	};
+}
+
+static inline bool queue_it_finished_impl(struct queue_it *it)
+{
+	return it->chunk == NULL || it->pos >= it->chunk->end;
+}
+
+static inline void * queue_it_val_impl(struct queue_it *it)
+{
+	assert(!queue_it_finished_impl(it));
+	return it->chunk->data + it->pos * it->item_size;
+}
+
+static inline void queue_it_next_impl(struct queue_it *it)
+{
+	assert(!queue_it_finished_impl(it));
+	++(it->pos);
+	if (it->pos < it->chunk->end)
+		return;
+	it->chunk = it->chunk->next;
+	it->pos = it->chunk ? it->chunk->begin : -1;
+}
+
+/** @endcond (internal) */
+/** @} (addtogroup generics) */
+
diff --git a/lib/generic/set.h b/lib/generic/set.h
new file mode 100644
index 0000000..9f6eb80
--- /dev/null
+++ b/lib/generic/set.h
@@ -0,0 +1,93 @@
+/*  Copyright (C) 2015-2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+/**
+ * @file set.h
+ * @brief A set abstraction implemented on top of map.
+ *
+ * @note The API is based on map.h, see it for more examples.
+ *
+ * # Example usage:
+ *
+ * @code{.c}
+ *      set_t set = set_make(NULL);
+ *
+ *      // Insert keys
+ *      if (set_add(&set, "princess") != 0 ||
+ *          set_add(&set, "prince")   != 0 ||
+ *          set_add(&set, "leia")     != 0) {
+ *          fail();
+ *      }
+ *
+ *      // Test membership
+ *      if (set_contains(&set, "leia")) {
+ *          success();
+ *      }
+ *
+ *      // Prefix search
+ *      int i = 0;
+ *      int count(const char *s, void *n) { (*(int *)n)++; return 0; }
+ *      if (set_walk_prefixed(set, "princ", count, &i) == 0) {
+ *          printf("%d matches\n", i);
+ *      }
+ *
+ *      // Delete
+ *      if (set_del(&set, "badkey") != 0) {
+ *          fail(); // No such key
+ *      }
+ *
+ *      // Clear the set
+ *      set_clear(&set);
+ * @endcode
+ *
+ * \addtogroup generics
+ * @{
+ */
+
+#pragma once
+
+#include <stddef.h>
+#include "map.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef map_t set_t;
+typedef int (set_walk_cb)(const char *, void *);
+
+/*! Creates an new, empty critbit set */
+#define set_make \
+	map_make
+
+/*! Returns non-zero if set contains str */
+#define set_contains(set, str) \
+	map_contains((set), (str))
+
+/*! Inserts str into set.  Returns 0 if new, 1 if already present, or ENOMEM. */
+#define set_add(set, str) \
+	map_set((set), (str), (void *)1)
+
+/*! Deletes str from the set, returns 0 on suceess */
+#define set_del(set, str) \
+	map_del((set), (str))
+
+/*! Clears the given set */
+#define set_clear(set) \
+	map_clear(set)
+
+/*! Calls callback for all strings in map  */
+#define set_walk(set, callback, baton) \
+	map_walk_prefixed((set), "", (callback), (baton))
+
+/*! Calls callback for all strings in set with the given prefix  */
+#define set_walk_prefixed(set, prefix, callback, baton) \
+	map_walk_prefixed((set), (prefix), (callback), (baton))
+
+
+#ifdef __cplusplus
+}
+#endif
+
+/** @} */
diff --git a/lib/generic/test_array.c b/lib/generic/test_array.c
new file mode 100644
index 0000000..98c5958
--- /dev/null
+++ b/lib/generic/test_array.c
@@ -0,0 +1,99 @@
+/*  Copyright (C) 2015-2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#include "tests/unit/test.h"
+#include "lib/generic/array.h"
+
+knot_mm_t global_mm;
+
+static void test_array(void **state)
+{
+	int ret = 0;
+	array_t(int) arr;
+	array_init(arr);
+
+	/* Basic access */
+	assert_int_equal(arr.len, 0);
+	assert_int_equal(array_push(arr, 5), 0);
+	assert_int_equal(arr.at[0], 5);
+	assert_int_equal(array_tail(arr), 5);
+	array_clear(arr);
+
+	/* Reserve capacity and fill. */
+	assert_true(array_reserve(arr, 5) >= 0);
+	for (unsigned i = 0; i < 100; ++i) {
+		ret = array_push(arr, i);
+		assert_true(ret >= 0);
+	}
+
+	/* Make sure reservation holds. */
+	assert_true(array_reserve(arr, 5) >= 0);
+
+	/* Delete elements. */
+	array_del(arr, 0);
+	while (arr.len > 0) {
+		array_pop(arr);
+	}
+
+	/* Overfill. */
+	for (unsigned i = 0; i < 4096; ++i) {
+		ret = array_push(arr, i);
+		assert_true(ret >= 0);
+	}
+
+	array_clear(arr);
+}
+
+/** Reservation through tracked memory allocator. */
+static int test_reserve(void *baton, void **mem, size_t elm_size, size_t want, size_t *have)
+{
+	if (want > *have) {
+		void *new_mem = mm_alloc(baton, elm_size * want);
+		if (*mem != NULL) {
+			memcpy(new_mem, *mem, (*have) * elm_size);
+			mm_free(baton, *mem);
+		}
+		*mem = new_mem;
+		*have = want;
+	}
+
+	return 0;
+}
+
+/** Reservation through fake memory allocator. */
+static int fake_reserve(void *baton, void **mem, size_t elm_size, size_t want, size_t *have)
+{
+	return -1;
+}
+
+static void test_array_mm(void **state)
+{
+	array_t(int) arr;
+	array_init(arr);
+
+	/* Reserve using fake memory allocator. */
+	assert_false(array_reserve_mm(arr, 5, fake_reserve, NULL) >= 0);
+
+	/* Reserve capacity and fill. */
+	assert_true(array_reserve_mm(arr, 100, test_reserve, &global_mm) >= 0);
+	for (unsigned i = 0; i < 100; ++i) {
+		int ret = array_push(arr, i);
+		assert_true(ret >= 0);
+	}
+
+	array_clear_mm(arr, mm_free, &global_mm);
+
+}
+
+int main(void)
+{
+	test_mm_ctx_init(&global_mm);
+
+	const UnitTest tests[] = {
+		unit_test(test_array),
+		unit_test(test_array_mm)
+	};
+
+	return run_tests(tests);
+}
diff --git a/lib/generic/test_lru.c b/lib/generic/test_lru.c
new file mode 100644
index 0000000..5cd4811
--- /dev/null
+++ b/lib/generic/test_lru.c
@@ -0,0 +1,111 @@
+/*  Copyright (C) 2014-2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "tests/unit/test.h"
+#include "lib/generic/lru.h"
+
+typedef lru_t(int) lru_int_t;
+#define HASH_SIZE 1024
+#define KEY_LEN(x) (strlen(x) + 1)
+
+/*
+ * Sample dictionary
+ */
+static const char *dict[] = {
+	"catagmatic", "prevaricator", "statoscope", "workhand", "benzamide",
+	"alluvia", "fanciful", "bladish", "Tarsius", "unfast", "appropriative",
+	"seraphically", "monkeypod", "deflectometer", "tanglesome", "zodiacal",
+	"physiologically", "economizer", "forcepslike", "betrumpet",
+	"Danization", "broadthroat", "randir", "usherette", "nephropyosis",
+	"hematocyanin", "chrysohermidin", "uncave", "mirksome", "podophyllum",
+	"siphonognathous", "indoor", "featheriness", "forwardation",
+	"archruler", "soricoid", "Dailamite", "carmoisin", "controllability",
+	"unpragmatical", "childless", "transumpt", "productive",
+	"thyreotoxicosis", "oversorrow", "disshadow", "osse", "roar",
+	"pantomnesia", "talcer", "hydrorrhoea", "Satyridae", "undetesting",
+	"smoothbored", "widower", "sivathere", "pendle", "saltation",
+	"autopelagic", "campfight", "unexplained", "Macrorhamphosus",
+	"absconsa", "counterflory", "interdependent", "triact", "reconcentration",
+	"oversharpness", "sarcoenchondroma", "superstimulate", "assessory",
+	"pseudepiscopacy", "telescopically", "ventriloque", "politicaster",
+	"Caesalpiniaceae", "inopportunity", "Helion", "uncompatible",
+	"cephaloclasia", "oversearch", "Mahayanistic", "quarterspace",
+	"bacillogenic", "hamartite", "polytheistical", "unescapableness",
+	"Pterophorus", "cradlemaking", "Hippoboscidae", "overindustrialize",
+	"perishless", "cupidity", "semilichen", "gadge", "detrimental",
+	"misencourage", "toparchia", "lurchingly", "apocatastasis"
+};
+
+static void test_insert(void **state)
+{
+	lru_int_t *lru = *state;
+	int dict_size = sizeof(dict) / sizeof(const char *);
+	int i;
+
+	for (i = 0; i < dict_size; i++) {
+		int *data = lru_get_new(lru, dict[i], KEY_LEN(dict[i]), NULL);
+		if (!data) {
+			continue;
+		}
+		*data = i;
+		assert_true(*lru_get_try(lru, dict[i], KEY_LEN(dict[i])) == i);
+	}
+}
+
+static void test_missing(void **state)
+{
+	lru_int_t *lru = *state;
+	const char *notin = "not in lru";
+	assert_true(lru_get_try(lru, notin, KEY_LEN(notin)) == NULL);
+}
+
+static void test_eviction(void **state)
+{
+	lru_int_t *lru = *state;
+	char key[16];
+	for (unsigned i = 0; i < HASH_SIZE; ++i) {
+		test_randstr(key, sizeof(key));
+		int *data = lru_get_new(lru, key, sizeof(key), NULL);
+		if (!data) {
+			continue;
+		}
+		*data = i;
+		if (*lru_get_try(lru, key, sizeof(key)) != i) {
+			assert_true(0);
+		}
+	}
+}
+
+static void test_init(void **state)
+{
+	lru_int_t *lru;
+	lru_create(&lru, HASH_SIZE, NULL, NULL);
+	assert_non_null(lru);
+	*state = lru;
+}
+
+static void test_deinit(void **state)
+{
+	lru_int_t *lru = *state;
+	lru_free(lru);
+}
+
+/* Program entry point */
+int main(int argc, char **argv)
+{
+	const UnitTest tests[] = {
+	        group_test_setup(test_init),
+	        unit_test(test_insert),
+		unit_test(test_missing),
+		unit_test(test_eviction),
+	        group_test_teardown(test_deinit)
+	};
+
+	return run_group_tests(tests);
+}
diff --git a/lib/generic/test_map.c b/lib/generic/test_map.c
new file mode 100644
index 0000000..7a04bfe
--- /dev/null
+++ b/lib/generic/test_map.c
@@ -0,0 +1,119 @@
+/*  Copyright (C) 2014-2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "tests/unit/test.h"
+#include "lib/generic/map.h"
+
+/*
+ * Sample dictionary
+ */
+static const char *dict[] = {
+	"catagmatic", "prevaricator", "statoscope", "workhand", "benzamide",
+	"alluvia", "fanciful", "bladish", "Tarsius", "unfast", "appropriative",
+	"seraphically", "monkeypod", "deflectometer", "tanglesome", "zodiacal",
+	"physiologically", "economizer", "forcepslike", "betrumpet",
+	"Danization", "broadthroat", "randir", "usherette", "nephropyosis",
+	"hematocyanin", "chrysohermidin", "uncave", "mirksome", "podophyllum",
+	"siphonognathous", "indoor", "featheriness", "forwardation",
+	"archruler", "soricoid", "Dailamite", "carmoisin", "controllability",
+	"unpragmatical", "childless", "transumpt", "productive",
+	"thyreotoxicosis", "oversorrow", "disshadow", "osse", "roar",
+	"pantomnesia", "talcer", "hydrorrhoea", "Satyridae", "undetesting",
+	"smoothbored", "widower", "sivathere", "pendle", "saltation",
+	"autopelagic", "campfight", "unexplained", "Macrorhamphosus",
+	"absconsa", "counterflory", "interdependent", "triact", "reconcentration",
+	"oversharpness", "sarcoenchondroma", "superstimulate", "assessory",
+	"pseudepiscopacy", "telescopically", "ventriloque", "politicaster",
+	"Caesalpiniaceae", "inopportunity", "Helion", "uncompatible",
+	"cephaloclasia", "oversearch", "Mahayanistic", "quarterspace",
+	"bacillogenic", "hamartite", "polytheistical", "unescapableness",
+	"Pterophorus", "cradlemaking", "Hippoboscidae", "overindustrialize",
+	"perishless", "cupidity", "semilichen", "gadge", "detrimental",
+	"misencourage", "toparchia", "lurchingly", "apocatastasis"
+};
+
+/* Insertions */
+static void test_insert(void **state)
+{
+	map_t *tree = *state;
+	int dict_size = sizeof(dict) / sizeof(const char *);
+	int i;
+
+	for (i = 0; i < dict_size; i++) {
+		assert_int_equal(map_set(tree, dict[i], (void *)dict[i]), 0);
+	}
+}
+
+/* Searching */
+static void test_get(void **state)
+{
+	map_t *tree = *state;
+	char *in;
+	const char *notin = "not in tree";
+
+	in = malloc(strlen(dict[23])+1);
+	strcpy(in, dict[23]);
+
+	assert_true(map_get(tree, in) == dict[23]);
+	assert_true(map_get(tree, notin) == NULL);
+	assert_true(map_get(tree, "") == NULL);
+	in[strlen(in)/2] = '\0';
+	assert_true(map_get(tree, in) == NULL);
+
+	free(in);
+}
+
+/* Deletion */
+static void test_delete(void **state)
+{
+	map_t *tree = *state;
+	assert_int_equal(map_del(tree, dict[91]), 0);
+	assert_false(map_contains(tree, dict[91]));
+	assert_int_equal(map_del(tree, "most likely not in tree"), 1);
+}
+
+/* Test null value existence */
+static void test_null_value(void **state)
+{
+	map_t *tree = *state;
+	char *key = "foo";
+
+	assert_int_equal(map_set(tree, key, (void *)0), 0);
+	assert_true(map_contains(tree, key));
+	assert_int_equal(map_del(tree, key), 0);
+}
+
+static void test_init(void **state)
+{
+	static map_t tree;
+	tree = map_make(NULL);
+	*state = &tree;
+	assert_non_null(*state);
+}
+
+static void test_deinit(void **state)
+{
+	map_t *tree = *state;
+	map_clear(tree);
+}
+
+/* Program entry point */
+int main(int argc, char **argv)
+{
+	const UnitTest tests[] = {
+	        group_test_setup(test_init),
+	        unit_test(test_insert),
+		unit_test(test_get),
+		unit_test(test_delete),
+		unit_test(test_null_value),
+	        group_test_teardown(test_deinit)
+	};
+
+	return run_group_tests(tests);
+}
diff --git a/lib/generic/test_pack.c b/lib/generic/test_pack.c
new file mode 100644
index 0000000..f25c199
--- /dev/null
+++ b/lib/generic/test_pack.c
@@ -0,0 +1,70 @@
+/*  Copyright (C) 2015-2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#include "tests/unit/test.h"
+#include "lib/generic/pack.h"
+
+#define U8(x) (const uint8_t *)(x)
+knot_mm_t global_mm;
+
+static void test_pack_std(void **state)
+{
+	int ret = 0;
+	pack_t pack;
+	pack_init(pack);
+	assert_int_equal(pack.len, 0);
+
+	/* Test that iterator on empty pack works */
+	assert_null(pack_head(pack));
+	assert_null(pack_tail(pack));
+	assert_null(pack_obj_find(&pack, U8(""), 1));
+	assert_int_equal(pack_obj_len(pack_head(pack)), 0);
+	assert_int_equal(pack_obj_del(&pack, U8(""), 1), -1);
+
+	/* Push/delete without reservation. */
+	assert_int_not_equal(pack_obj_push(&pack, U8(""), 1), 0);
+	assert_int_not_equal(pack_obj_del(&pack, U8(""), 1), 0);
+
+	/* Reserve capacity and fill. */
+	assert_true(pack_reserve(pack, 10, 10 * 2) >= 0);
+	for (unsigned i = 0; i < 10; ++i) {
+		ret = pack_obj_push(&pack, U8("de"), 2);
+		assert_true(ret >= 0);
+	}
+
+	/* Iterate */
+	uint8_t *it = pack_head(pack);
+	assert_non_null(it);
+	unsigned count = 0;
+	while (it != pack_tail(pack)) {
+		assert_int_equal(pack_obj_len(it), 2);
+		assert_true(memcmp(pack_obj_val(it), "de", 2) == 0);
+		it = pack_obj_next(it);
+		count += 1;
+	}
+
+	/* Find */
+	it = pack_obj_find(&pack, U8("de"), 2);
+	assert_non_null(it);
+	it = pack_obj_find(&pack, U8("ed"), 2);
+	assert_null(it);
+
+	/* Delete */
+	assert_int_not_equal(pack_obj_del(&pack, U8("be"), 2), 0);
+	assert_int_equal(pack_obj_del(&pack, U8("de"), 2), 0);
+	assert_int_equal(pack.len, 9*(2+2)); /* 9 objects, length=2 */
+
+	pack_clear(pack);
+}
+
+int main(void)
+{
+	test_mm_ctx_init(&global_mm);
+
+	const UnitTest tests[] = {
+		unit_test(test_pack_std),
+	};
+
+	return run_tests(tests);
+}
diff --git a/lib/generic/test_queue.c b/lib/generic/test_queue.c
new file mode 100644
index 0000000..3a6b5be
--- /dev/null
+++ b/lib/generic/test_queue.c
@@ -0,0 +1,71 @@
+/*  Copyright (C) 2018 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#include "tests/unit/test.h"
+#include "lib/generic/queue.h"
+
+/* The main intention is to use queues with pointers, so we test the same-sized int. */
+typedef queue_t(ptrdiff_t) queue_int_t;
+typedef queue_it_t(int) queue_int_it_t;
+
+static void test_int(void **state_)
+{
+	queue_int_t q;
+	queue_init(q);
+
+	/* Case of emptying the queue (and using again) has been broken for a long time. */
+	queue_push(q, 2);
+	queue_pop(q);
+	queue_push(q, 4);
+	queue_pop(q);
+
+	queue_push_head(q, 2);
+	queue_push_head(q, 1);
+	queue_push_head(q, 0);
+	for (int i = 0; i < 100; ++i) {
+		assert_int_equal(queue_head(q), i);
+		queue_push(q, i + 3);
+		queue_pop(q);
+	}
+	assert_int_equal(queue_len(q), 3);
+	for (int i = 99; i > 0; --i) {
+		assert_int_equal(queue_head(q), i + 1);
+		queue_push_head(q, i);
+	}
+	assert_int_equal(queue_len(q), 3 + 99);
+
+	/* Basic iterator test. */
+	{
+		int i = 0;
+		for (queue_int_it_t it = queue_it_begin(q); !queue_it_finished(it);
+		     queue_it_next(it)) {
+			++queue_it_val(it);
+			++i;
+		}
+		assert_int_equal(queue_len(q), i);
+	}
+
+	queue_deinit(q);
+	queue_init(q);
+
+	for (int i = 0; i < 100; ++i) {
+		queue_push(q, 2*i);
+		queue_push(q, 2*i + 1);
+		assert_int_equal(queue_head(q), i);
+		queue_pop(q);
+	}
+
+	queue_deinit(q);
+}
+
+
+int main(void)
+{
+	const UnitTest tests[] = {
+		unit_test(test_int),
+	};
+
+	return run_tests(tests);
+}
+
diff --git a/lib/generic/test_set.c b/lib/generic/test_set.c
new file mode 100644
index 0000000..adb5222
--- /dev/null
+++ b/lib/generic/test_set.c
@@ -0,0 +1,221 @@
+/*
+ * critbit89 - A crit-bit tree implementation for strings in C89
+ * Written by Jonas Gehring <jonas@jgehring.net>
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "tests/unit/test.h"
+#include "lib/generic/set.h"
+#include "lib/utils.h"
+
+
+/*
+ * Sample dictionary: 100 random words from /usr/share/dict/words
+ * Generated using random.org:
+ * MAX=`wc -l < /usr/share/dict/words | tr -d " "`
+ * for i in `curl "http://www.random.org/integers/?num=100&min=1&max=$MAX&col=1&base=10&format=plain&rnd=new"`; do
+ *   nl /usr/share/dict/words | grep -w $i | tr -d "0-9\t "
+ * done
+ */
+static const char *dict[] = {
+	"catagmatic", "prevaricator", "statoscope", "workhand", "benzamide",
+	"alluvia", "fanciful", "bladish", "Tarsius", "unfast", "appropriative",
+	"seraphically", "monkeypod", "deflectometer", "tanglesome", "zodiacal",
+	"physiologically", "economizer", "forcepslike", "betrumpet",
+	"Danization", "broadthroat", "randir", "usherette", "nephropyosis",
+	"hematocyanin", "chrysohermidin", "uncave", "mirksome", "podophyllum",
+	"siphonognathous", "indoor", "featheriness", "forwardation",
+	"archruler", "soricoid", "Dailamite", "carmoisin", "controllability",
+	"unpragmatical", "childless", "transumpt", "productive",
+	"thyreotoxicosis", "oversorrow", "disshadow", "osse", "roar",
+	"pantomnesia", "talcer", "hydrorrhoea", "Satyridae", "undetesting",
+	"smoothbored", "widower", "sivathere", "pendle", "saltation",
+	"autopelagic", "campfight", "unexplained", "Macrorhamphosus",
+	"absconsa", "counterflory", "interdependent", "triact", "reconcentration",
+	"oversharpness", "sarcoenchondroma", "superstimulate", "assessory",
+	"pseudepiscopacy", "telescopically", "ventriloque", "politicaster",
+	"Caesalpiniaceae", "inopportunity", "Helion", "uncompatible",
+	"cephaloclasia", "oversearch", "Mahayanistic", "quarterspace",
+	"bacillogenic", "hamartite", "polytheistical", "unescapableness",
+	"Pterophorus", "cradlemaking", "Hippoboscidae", "overindustrialize",
+	"perishless", "cupidity", "semilichen", "gadge", "detrimental",
+	"misencourage", "toparchia", "lurchingly", "apocatastasis"
+};
+
+/* Insertions */
+static void test_insert(void **state)
+{
+	set_t *set = *state;
+	int dict_size = sizeof(dict) / sizeof(const char *);
+	int i;
+
+	for (i = 0; i < dict_size; i++) {
+		assert_int_equal(set_add(set, dict[i]), 0);
+	}
+}
+
+/* Insertion of duplicate element */
+static void test_insert_dup(void **state)
+{
+	set_t *set = *state;
+	int dict_size = sizeof(dict) / sizeof(const char *);
+	int i;
+
+	for (i = 0; i < dict_size; i++) {
+		if (!set_contains(set, dict[i])) {
+			continue;
+		}
+		assert_int_equal(set_add(set, dict[i]), 1);
+	}
+}
+
+/* Searching */
+static void test_contains(void **state)
+{
+	set_t *set = *state;
+	char *in;
+	const char *notin = "not in set";
+
+	in = malloc(strlen(dict[23])+1);
+	strcpy(in, dict[23]);
+
+	assert_true(set_contains(set, in));
+	assert_false(set_contains(set, notin));
+	assert_false(set_contains(set, ""));
+	in[strlen(in)/2] = '\0';
+	assert_false(set_contains(set, in));
+
+	free(in);
+}
+
+/* Count number of items */
+static int count_cb(const char *s, void *_, void *n) { (*(int *)n)++; return 0; }
+static void test_complete(set_t *set, int n)
+{
+	int i = 0;
+	if (set_walk(set, count_cb, &i) != 0) {
+		abort();
+	}
+	if (i != n) {
+		abort();
+	}
+}
+static void test_complete_full(void **state) { test_complete(*state, sizeof(dict) / sizeof(const char *)); }
+static void test_complete_zero(void **state) { test_complete(*state, 0); }
+
+/* Deletion */
+static void test_delete(void **state)
+{
+	set_t *set = *state;
+	assert_int_equal(set_del(set, dict[91]), 0);
+	assert_int_equal(set_del(set, "most likely not in set"), 1);
+}
+
+/* Complete deletion */
+static void test_delete_all(void **state)
+{
+	set_t *set = *state;
+	int dict_size = sizeof(dict) / sizeof(const char *);
+	int i;
+
+	for (i = 0; i < dict_size; i++) {
+		if (!set_contains(set, dict[i])) {
+			continue;
+		}
+		assert_int_equal(set_del(set, dict[i]), 0);
+	}
+}
+
+/* Fake allocator */
+static void *fake_malloc(void *b, size_t s) { return NULL; }
+static void test_allocator(void **state)
+{
+	knot_mm_t fake_pool = { .ctx = NULL, .alloc = fake_malloc, .free = NULL };
+	set_t set = set_make(&fake_pool);
+	assert_int_equal(set_add(&set, dict[0]), ENOMEM);
+}
+
+/* Empty set */
+static void test_empty(void **state)
+{
+	set_t *set = *state;
+	assert_int_equal(set_contains(set, dict[1]), 0);
+	assert_int_not_equal(set_del(set, dict[1]), 0);
+}
+
+/* Prefix walking */
+static void test_prefixes(void **state)
+{
+	set_t *set = *state;
+	int i = 0;
+	if ((set_add(set, "1str") != 0) ||
+			(set_add(set, "11str2") != 0) ||
+			(set_add(set, "12str") != 0) ||
+			(set_add(set, "11str") != 0)) {
+		assert_int_equal(1, 0);
+	}
+
+	assert_int_equal(set_walk_prefixed(set, "11", count_cb, &i), 0);
+	assert_int_equal(i, 2);
+	i = 0;
+	assert_int_equal(set_walk_prefixed(set, "13", count_cb, &i), 0);
+	assert_int_equal(i, 0);
+	i = 0;
+	assert_int_equal(set_walk_prefixed(set, "12345678", count_cb, &i), 0);
+	assert_int_equal(i, 0);
+	i = 0;
+	assert_int_equal(set_walk_prefixed(set, "11str", count_cb, &i), 0);
+	assert_int_equal(i, 2);
+}
+
+static void test_clear(void **state)
+{
+	set_t *set = *state;
+	set_clear(set);
+}
+
+static void test_init(void **state)
+{
+	static set_t set;
+	set = set_make(NULL);
+	*state = &set;
+	assert_non_null(*state);
+}
+
+static void test_deinit(void **state)
+{
+	set_t *set = *state;
+	set_clear(set);
+}
+
+/* Program entry point */
+int main(int argc, char **argv)
+{
+	const UnitTest tests[] = {
+	        group_test_setup(test_init),
+	        unit_test(test_insert),
+	        unit_test(test_complete_full),
+	        unit_test(test_insert_dup),
+	        unit_test(test_contains),
+		unit_test(test_delete),
+		unit_test(test_clear),
+		unit_test(test_insert),
+		unit_test(test_complete_full),
+		unit_test(test_delete_all),
+		unit_test(test_complete_zero),
+		unit_test(test_allocator),
+		unit_test(test_clear),
+		unit_test(test_empty),
+		unit_test(test_insert),
+		unit_test(test_prefixes),
+	        group_test_teardown(test_deinit)
+	};
+
+	return run_group_tests(tests);
+}
diff --git a/lib/generic/test_trie.c b/lib/generic/test_trie.c
new file mode 100644
index 0000000..6740948
--- /dev/null
+++ b/lib/generic/test_trie.c
@@ -0,0 +1,154 @@
+/*  Copyright (C) 2018 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#include "lib/generic/trie.h"
+#include "tests/unit/test.h"
+
+static const char *dict[] = {
+	"catagmatic", "prevaricator", "statoscope", "workhand", "benzamide",
+	"work", "workhands", // have some keys that are prefixes of each other
+	"alluvia", "fanciful", "bladish", "Tarsius", "unfast", "appropriative",
+	"seraphically", "monkeypod", "deflectometer", "tanglesome", "zodiacal",
+	"physiologically", "economizer", "forcepslike", "betrumpet",
+	"Danization", "broadthroat", "randir", "usherette", "nephropyosis",
+	"hematocyanin", "chrysohermidin", "uncave", "mirksome", "podophyllum",
+	"siphonognathous", "indoor", "featheriness", "forwardation",
+	"archruler", "soricoid", "Dailamite", "carmoisin", "controllability",
+	"unpragmatical", "childless", "transumpt", "productive",
+	"thyreotoxicosis", "oversorrow", "disshadow", "osse", "roar",
+	"pantomnesia", "talcer", "hydrorrhoea", "Satyridae", "undetesting",
+	"smoothbored", "widower", "sivathere", "pendle", "saltation",
+	"autopelagic", "campfight", "unexplained", "Macrorhamphosus",
+	"absconsa", "counterflory", "interdependent", "triact", "reconcentration",
+	"oversharpness", "sarcoenchondroma", "superstimulate", "assessory",
+	"pseudepiscopacy", "telescopically", "ventriloque", "politicaster",
+	"Caesalpiniaceae", "inopportunity", "Helion", "uncompatible",
+	"cephaloclasia", "oversearch", "Mahayanistic", "quarterspace",
+	"bacillogenic", "hamartite", "polytheistical", "unescapableness",
+	"Pterophorus", "cradlemaking", "Hippoboscidae", "overindustrialize",
+	"perishless", "cupidity", "semilichen", "gadge", "detrimental",
+	"misencourage", "toparchia", "lurchingly", "apocatastasis"
+};
+#define KEY_LEN(x) (strlen(x) + 1)
+static const int dict_size = sizeof(dict) / sizeof(const char *);
+
+static void test_init(void **state)
+{
+	trie_t *t = trie_create(NULL);
+	assert_non_null(t);
+	*state = t;
+}
+
+static void test_insert(void **state)
+{
+	trie_t *t = *state;
+
+	for (int i = 0; i < dict_size; ++i) {
+		trie_val_t *data = trie_get_ins(t, dict[i], KEY_LEN(dict[i]));
+		assert_non_null(data);
+		assert_null(*data);
+		*data = (char *)NULL + i; // yes, ugly
+		assert_ptr_equal(trie_get_try(t, dict[i], KEY_LEN(dict[i])), data);
+	}
+	assert_int_equal(trie_weight(t), dict_size);
+}
+
+static void test_missing(void **state)
+{
+	trie_t *t = *state;
+	const char *notin = "p";
+	assert_null(trie_get_try(t, notin, KEY_LEN(notin)));
+}
+
+static int cmpstringp(const void *p1, const void *p2)
+{
+	return strcmp(* (char * const *) p1, * (char * const *) p2);
+}
+
+static void test_iter(void **state)
+{
+	// prepare sorted dictionary
+	char *dict_sorted[dict_size];
+	memcpy(dict_sorted, dict, sizeof(dict));
+	qsort(dict_sorted, dict_size, sizeof(dict[0]), cmpstringp);
+
+	// iterate and check the order is consistent
+	trie_t *t = *state;
+	trie_it_t *it = trie_it_begin(t);
+	for (int i = 0; i < dict_size; ++i, trie_it_next(it)) {
+		assert_false(trie_it_finished(it));
+		size_t len;
+		const char *key = trie_it_key(it, &len);
+		assert_int_equal(KEY_LEN(key), len);
+		assert_string_equal(key, dict_sorted[i]);
+		assert_ptr_equal(dict[(char *)*trie_it_val(it) - (char *)NULL],
+				 dict_sorted[i]);
+	}
+	assert_true(trie_it_finished(it));
+	trie_it_free(it);
+}
+
+static void test_queue(void **state)
+{
+	trie_t *t = *state;
+	// remove all the elements in ascending order
+	for (int i = 0; i < dict_size; ++i) {
+		char *key;
+		uint32_t len;
+		trie_val_t *data = trie_get_first(t, &key, &len);
+		assert_non_null(key);
+		assert_int_equal(len, KEY_LEN(key));
+		assert_non_null(data);
+		ptrdiff_t key_i = (char *)*data - (char *)NULL;
+		assert_string_equal(key, dict[key_i]);
+
+		len = 30;
+		char key_buf[len];
+		ptrdiff_t key_i_new;
+		int ret = trie_del_first(t, key_buf, &len, (trie_val_t *)&key_i_new);
+		assert_int_equal(ret, kr_ok());
+		assert_int_equal(KEY_LEN(key_buf), len);
+		assert_int_equal(key_i, key_i_new);
+		assert_string_equal(dict[key_i], key_buf);
+	}
+}
+
+static void test_leq_bug(void **state)
+{
+	/* We use different contents of the trie,
+	 * so that the particular bug would've been triggered. */
+	trie_t *t = trie_create(NULL);
+	char key = 'a';
+	trie_get_ins(t, &key, sizeof(key));
+
+	key = (char)0xff;
+	trie_val_t *val;
+	int ret = trie_get_leq(t, &key, sizeof(key), &val);
+	assert_int_equal(ret, 1);
+	trie_free(t);
+}
+
+static void test_deinit(void **state)
+{
+	trie_t *t = *state;
+	trie_free(t);
+	*state = NULL;
+}
+
+/* Program entry point */
+int main(int argc, char **argv)
+{
+	const UnitTest tests[] = {
+	        group_test_setup(test_init),
+	        unit_test(test_insert),
+		unit_test(test_leq_bug),
+		unit_test(test_missing),
+		unit_test(test_iter),
+		unit_test(test_queue),
+	        group_test_teardown(test_deinit)
+	};
+
+	return run_group_tests(tests);
+}
+
diff --git a/lib/generic/trie.c b/lib/generic/trie.c
new file mode 100644
index 0000000..682b159
--- /dev/null
+++ b/lib/generic/trie.c
@@ -0,0 +1,900 @@
+/*  Copyright (C) 2016-2018 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+
+    The code originated from https://github.com/fanf2/qp/blob/master/qp.c
+    at revision 5f6d93753.
+ */
+
+#include <assert.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "lib/generic/trie.h"
+#include "lib/utils.h"
+#include "contrib/ucw/lib.h"
+
+#if defined(__i386) || defined(__x86_64) || defined(_M_IX86) \
+	|| (defined(__BYTE_ORDER__) && defined(__ORDER_LITTLE_ENDIAN) \
+		&& __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__)
+
+	/*!
+	 * \brief Use a pointer alignment hack to save memory.
+	 *
+	 * When on, isbranch() relies on the fact that in leaf_t the first pointer
+	 * is aligned on multiple of 4 bytes and that the flags bitfield is
+	 * overlaid over the lowest two bits of that pointer.
+	 * Neither is really guaranteed by the C standards; the second part should
+	 * be OK with x86_64 ABI and most likely any other little-endian platform.
+	 * It would be possible to manipulate the right bits portably, but it would
+	 * complicate the code nontrivially. C++ doesn't even guarantee type-punning.
+	 * In debug mode we check this works OK when creating a new trie instance.
+	 */
+	#define FLAGS_HACK 1
+#else
+	#define FLAGS_HACK 0
+#endif
+
+typedef unsigned char byte;
+#ifndef uint
+typedef unsigned int uint;
+#define uint uint
+#endif
+typedef uint bitmap_t; /*! Bit-maps, using the range of 1<<0 to 1<<16 (inclusive). */
+
+typedef struct {
+	uint32_t len; // 32 bits are enough for key lengths; probably even 16 bits would be.
+	char chars[];
+} tkey_t;
+
+/*! \brief Leaf of trie. */
+typedef struct {
+	#if !FLAGS_HACK
+		byte flags;
+	#endif
+	tkey_t *key; /*!< The pointer must be aligned to 4-byte multiples! */
+	trie_val_t val;
+} leaf_t;
+
+/*! \brief A trie node is either leaf_t or branch_t. */
+typedef union node node_t;
+
+/*!
+ * \brief Branch node of trie.
+ *
+ * - The flags distinguish whether the node is a leaf_t (0), or a branch
+ *   testing the more-important nibble (1) or the less-important one (2).
+ * - It stores the index of the byte that the node tests.  The combined
+ *   value (index*4 + flags) increases in branch nodes as you go deeper
+ *   into the trie.  All the keys below a branch are identical up to the
+ *   nibble identified by the branch.  Indices have to be stored because
+ *   we skip any branch nodes that would have a single child.
+ *   (Consequently, the skipped parts of key have to be validated in a leaf.)
+ * - The bitmap indicates which subtries are present.  The present child nodes
+ *   are stored in the twigs array (with no holes between them).
+ * - To simplify storing keys that are prefixes of each other, the end-of-string
+ *   position is treated as another nibble value, ordered before all others.
+ *   That affects the bitmap and twigs fields.
+ *
+ * \note The branch nodes are never allocated individually, but they are
+ *   always part of either the root node or the twigs array of the parent.
+ */
+typedef struct {
+	#if FLAGS_HACK
+		uint32_t flags  : 2,
+		         bitmap : 17; /*!< The first bitmap bit is for end-of-string child. */
+	#else
+		byte flags;
+		uint32_t bitmap;
+	#endif
+	uint32_t index;
+	node_t *twigs;
+} branch_t;
+
+union node {
+	leaf_t leaf;
+	branch_t branch;
+};
+
+struct trie {
+	node_t root; // undefined when weight == 0, see empty_root()
+	size_t weight;
+	knot_mm_t mm;
+};
+
+/*! \brief Make the root node empty (debug-only). */
+static inline void empty_root(node_t *root) {
+#ifndef NDEBUG
+	*root = (node_t){ .branch = {
+		.flags = 3, // invalid value that fits
+		.bitmap = 0,
+		.index = -1,
+		.twigs = NULL
+	} };
+#endif
+}
+
+/*! \brief Check that unportable code works OK (debug-only). */
+static void assert_portability(void) {
+#if FLAGS_HACK
+	assert(((union node){ .leaf = {
+			.key = (tkey_t *)(((uint8_t *)NULL) + 1),
+			.val = NULL
+		} }).branch.flags == 1);
+#endif
+}
+
+/*! \brief Propagate error codes. */
+#define ERR_RETURN(x) \
+	do { \
+		int err_code_ = x; \
+		if (unlikely(err_code_ != KNOT_EOK)) \
+			return err_code_; \
+	} while (false)
+
+/*!
+ * \brief Count the number of set bits.
+ *
+ * \TODO This implementation may be relatively slow on some HW.
+ */
+static uint bitmap_weight(bitmap_t w)
+{
+	assert((w & ~((1 << 17) - 1)) == 0); // using the least-important 17 bits
+	return __builtin_popcount(w);
+}
+
+/*! \brief Only keep the lowest bit in the bitmap (least significant -> twigs[0]). */
+static bitmap_t bitmap_lowest_bit(bitmap_t w)
+{
+	assert((w & ~((1 << 17) - 1)) == 0); // using the least-important 17 bits
+	return 1 << __builtin_ctz(w);
+}
+
+/*! \brief Test flags to determine type of this node. */
+static bool isbranch(const node_t *t)
+{
+	uint f = t->branch.flags;
+	assert(f <= 2);
+	return f != 0;
+}
+
+/*! \brief Make a bitmask for testing a branch bitmap. */
+static bitmap_t nibbit(byte k, uint flags)
+{
+	uint shift = (2 - flags) << 2;
+	uint nibble = (k >> shift) & 0xf;
+	return 1 << (nibble + 1/*because of prefix keys*/);
+}
+
+/*! \brief Extract a nibble from a key and turn it into a bitmask. */
+static bitmap_t twigbit(const node_t *t, const char *key, uint32_t len)
+{
+	assert(isbranch(t));
+	uint i = t->branch.index;
+
+	if (i >= len)
+		return 1 << 0; // leaf position
+
+	return nibbit((byte)key[i], t->branch.flags);
+}
+
+/*! \brief Test if a branch node has a child indicated by a bitmask. */
+static bool hastwig(const node_t *t, bitmap_t bit)
+{
+	assert(isbranch(t));
+	return t->branch.bitmap & bit;
+}
+
+/*! \brief Compute offset of an existing child in a branch node. */
+static uint twigoff(const node_t *t, bitmap_t b)
+{
+	assert(isbranch(t));
+	return bitmap_weight(t->branch.bitmap & (b - 1));
+}
+
+/*! \brief Get pointer to a particular child of a branch node. */
+static node_t* twig(node_t *t, uint i)
+{
+	assert(isbranch(t));
+	return &t->branch.twigs[i];
+}
+
+/*!
+ * \brief For a branch nod, compute offset of a child and child count.
+ *
+ * Having this separate might be meaningful for performance optimization.
+ */
+#define TWIGOFFMAX(off, max, t, b) do {			\
+		(off) = twigoff((t), (b));		\
+		(max) = bitmap_weight((t)->branch.bitmap);\
+	} while(0)
+
+/*! \brief Simple string comparator. */
+static int key_cmp(const char *k1, uint32_t k1_len, const char *k2, uint32_t k2_len)
+{
+	int ret = memcmp(k1, k2, MIN(k1_len, k2_len));
+	if (ret != 0) {
+		return ret;
+	}
+
+	/* Key string is equal, compare lengths. */
+	if (k1_len == k2_len) {
+		return 0;
+	} else if (k1_len < k2_len) {
+		return -1;
+	} else {
+		return 1;
+	}
+}
+
+trie_t* trie_create(knot_mm_t *mm)
+{
+	assert_portability();
+	trie_t *trie = mm_alloc(mm, sizeof(trie_t));
+	if (trie != NULL) {
+		empty_root(&trie->root);
+		trie->weight = 0;
+		if (mm != NULL)
+			trie->mm = *mm;
+		else
+			mm_ctx_init(&trie->mm);
+	}
+	return trie;
+}
+
+/*! \brief Free anything under the trie node, except for the passed pointer itself. */
+static void clear_trie(node_t *trie, knot_mm_t *mm)
+{
+	if (!isbranch(trie)) {
+		mm_free(mm, trie->leaf.key);
+	} else {
+		branch_t *b = &trie->branch;
+		int len = bitmap_weight(b->bitmap);
+		for (int i = 0; i < len; ++i)
+			clear_trie(b->twigs + i, mm);
+		mm_free(mm, b->twigs);
+	}
+}
+
+void trie_free(trie_t *tbl)
+{
+	if (tbl == NULL)
+		return;
+	if (tbl->weight)
+		clear_trie(&tbl->root, &tbl->mm);
+	mm_free(&tbl->mm, tbl);
+}
+
+void trie_clear(trie_t *tbl)
+{
+	assert(tbl);
+	if (!tbl->weight)
+		return;
+	clear_trie(&tbl->root, &tbl->mm);
+	empty_root(&tbl->root);
+	tbl->weight = 0;
+}
+
+size_t trie_weight(const trie_t *tbl)
+{
+	assert(tbl);
+	return tbl->weight;
+}
+
+struct found {
+	leaf_t *l;	/**< the found leaf (NULL if not found) */
+	branch_t *p;	/**< the leaf's parent (if exists) */
+	bitmap_t b;	/**< bit-mask with a single bit marking l under p */
+};
+/** Search trie for an item with the given key (equality only). */
+static struct found find_equal(trie_t *tbl, const char *key, uint32_t len)
+{
+	assert(tbl);
+	struct found ret0;
+	memset(&ret0, 0, sizeof(ret0));
+	if (!tbl->weight)
+		return ret0;
+	/* Current node and parent while descending (returned values basically). */
+	node_t *t = &tbl->root;
+	branch_t *p = NULL;
+	bitmap_t b = 0;
+	while (isbranch(t)) {
+		__builtin_prefetch(t->branch.twigs);
+		b = twigbit(t, key, len);
+		if (!hastwig(t, b))
+			return ret0;
+		p = &t->branch;
+		t = twig(t, twigoff(t, b));
+	}
+	if (key_cmp(key, len, t->leaf.key->chars, t->leaf.key->len) != 0)
+		return ret0;
+	return (struct found) {
+		.l = &t->leaf,
+		.p = p,
+		.b = b,
+	};
+}
+/** Find item with the first key (lexicographical order). */
+static struct found find_first(trie_t *tbl)
+{
+	assert(tbl);
+	if (!tbl->weight) {
+		struct found ret0;
+		memset(&ret0, 0, sizeof(ret0));
+		return ret0;
+	}
+	/* Current node and parent while descending (returned values basically). */
+	node_t *t = &tbl->root;
+	branch_t *p = NULL;
+	while (isbranch(t)) {
+		p = &t->branch;
+		t = &p->twigs[0];
+	}
+	return (struct found) {
+		.l = &t->leaf,
+		.p = p,
+		.b = p ? bitmap_lowest_bit(p->bitmap) : 0,
+	};
+}
+
+trie_val_t* trie_get_try(trie_t *tbl, const char *key, uint32_t len)
+{
+	struct found found = find_equal(tbl, key, len);
+	return found.l ? &found.l->val : NULL;
+}
+
+trie_val_t* trie_get_first(trie_t *tbl, char **key, uint32_t *len)
+{
+	struct found found = find_first(tbl);
+	if (!found.l)
+		return NULL;
+	if (key)
+		*key = found.l->key->chars;
+	if (len)
+		*len = found.l->key->len;
+	return &found.l->val;
+}
+
+/** Delete the found element (if any) and return value (unless NULL is passed) */
+static int del_found(trie_t *tbl, struct found found, trie_val_t *val)
+{
+	if (!found.l)
+		return KNOT_ENOENT;
+	mm_free(&tbl->mm, found.l->key);
+	if (val != NULL)
+		*val = found.l->val; // we return trie_val_t directly when deleting
+	--tbl->weight;
+	branch_t * const p = found.p; // short-hand
+	if (unlikely(!p)) { // whole trie was a single leaf
+		assert(tbl->weight == 0);
+		empty_root(&tbl->root);
+		return KNOT_EOK;
+	}
+	// remove leaf t as child of p; get child index via pointer arithmetic
+	int ci = ((union node *)found.l) - p->twigs,
+	    cc = bitmap_weight(p->bitmap); // child count
+	assert(ci >= 0 && ci < cc);
+
+	if (cc == 2) { // collapse binary node p: move the other child to this node
+		node_t *twigs = p->twigs;
+		(*(union node *)p) = twigs[1 - ci]; // it might be a leaf or branch
+		mm_free(&tbl->mm, twigs);
+		return KNOT_EOK;
+	}
+	memmove(p->twigs + ci, p->twigs + ci + 1, sizeof(node_t) * (cc - ci - 1));
+	p->bitmap &= ~found.b;
+	node_t *twigs = mm_realloc(&tbl->mm, p->twigs, sizeof(node_t) * (cc - 1),
+	                           sizeof(node_t) * cc);
+	if (likely(twigs != NULL))
+		p->twigs = twigs;
+		/* We can ignore mm_realloc failure, only beware that next time
+		 * the prev_size passed to it wouldn't be correct; TODO? */
+	return KNOT_EOK;
+}
+
+int trie_del(trie_t *tbl, const char *key, uint32_t len, trie_val_t *val)
+{
+	struct found found = find_equal(tbl, key, len);
+	return del_found(tbl, found, val);
+}
+
+int trie_del_first(trie_t *tbl, char *key, uint32_t *len, trie_val_t *val)
+{
+	struct found found = find_first(tbl);
+	if (!found.l)
+		return KNOT_ENOENT;
+	if (key) {
+		if (!len)
+			return KNOT_EINVAL;
+		if (*len < found.l->key->len)
+			return kr_error(ENOSPC);
+		memcpy(key, found.l->key->chars, found.l->key->len);
+	}
+	if (len) { // makes sense even with key == NULL
+		*len = found.l->key->len;
+	}
+	return del_found(tbl, found, val);
+}
+
+/*!
+ * \brief Stack of nodes, storing a path down a trie.
+ *
+ * The structure also serves directly as the public trie_it_t type,
+ * in which case it always points to the current leaf, unless we've finished
+ * (i.e. it->len == 0).
+ */
+typedef struct trie_it {
+	node_t* *stack; /*!< The stack; malloc is used directly instead of mm. */
+	uint32_t len;   /*!< Current length of the stack. */
+	uint32_t alen;  /*!< Allocated/available length of the stack. */
+	/*! \brief Initial storage for \a stack; it should fit in many use cases. */
+	node_t* stack_init[60];
+} nstack_t;
+
+/*! \brief Create a node stack containing just the root (or empty). */
+static void ns_init(nstack_t *ns, trie_t *tbl)
+{
+	assert(tbl);
+	ns->stack = ns->stack_init;
+	ns->alen = sizeof(ns->stack_init) / sizeof(ns->stack_init[0]);
+	if (tbl->weight) {
+		ns->len = 1;
+		ns->stack[0] = &tbl->root;
+	} else {
+		ns->len = 0;
+	}
+}
+
+/*! \brief Free inside of the stack, i.e. not the passed pointer itself. */
+static void ns_cleanup(nstack_t *ns)
+{
+	assert(ns && ns->stack);
+	if (likely(ns->stack == ns->stack_init))
+		return;
+	free(ns->stack);
+	#ifndef NDEBUG
+		ns->stack = NULL;
+		ns->alen = 0;
+	#endif
+}
+
+/*! \brief Allocate more space for the stack. */
+static int ns_longer_alloc(nstack_t *ns)
+{
+	ns->alen *= 2;
+	size_t new_size = sizeof(nstack_t) + ns->alen * sizeof(node_t *);
+	node_t **st;
+	if (ns->stack == ns->stack_init) {
+		st = malloc(new_size);
+		if (st != NULL)
+			memcpy(st, ns->stack, ns->len * sizeof(node_t *));
+	} else {
+		st = realloc(ns->stack, new_size);
+	}
+	if (st == NULL)
+		return KNOT_ENOMEM;
+	ns->stack = st;
+	return KNOT_EOK;
+}
+
+/*! \brief Ensure the node stack can be extended by one. */
+static inline int ns_longer(nstack_t *ns)
+{
+	// get a longer stack if needed
+	if (likely(ns->len < ns->alen))
+		return KNOT_EOK;
+	return ns_longer_alloc(ns); // hand-split the part suitable for inlining
+}
+
+/*!
+ * \brief Find the "branching point" as if searching for a key.
+ *
+ *  The whole path to the point is kept on the passed stack;
+ *  always at least the root will remain on the top of it.
+ *  Beware: the precise semantics of this function is rather tricky.
+ *  The top of the stack will contain: the corresponding leaf if exact match is found;
+ *  or the immediate node below a branching-point-on-edge or the branching-point itself.
+ *
+ *  \param info   Set position of the point of first mismatch (in index and flags).
+ *  \param first  Set the value of the first non-matching character (from trie),
+ *                optionally; end-of-string character has value -256 (that's why it's int).
+ *                Note: the character is converted to *unsigned* char (i.e. 0..255),
+ *                as that's the ordering used in the trie.
+ *
+ *  \return KNOT_EOK or KNOT_ENOMEM.
+ */
+static int ns_find_branch(nstack_t *ns, const char *key, uint32_t len,
+                          branch_t *info, int *first)
+{
+	assert(ns && ns->len && info);
+	// First find some leaf with longest matching prefix.
+	while (isbranch(ns->stack[ns->len - 1])) {
+		ERR_RETURN(ns_longer(ns));
+		node_t *t = ns->stack[ns->len - 1];
+		__builtin_prefetch(t->branch.twigs);
+		bitmap_t b = twigbit(t, key, len);
+		// Even if our key is missing from this branch we need to
+		// keep iterating down to a leaf. It doesn't matter which
+		// twig we choose since the keys are all the same up to this
+		// index. Note that blindly using twigoff(t, b) can cause
+		// an out-of-bounds index if it equals twigmax(t).
+		uint i = hastwig(t, b) ? twigoff(t, b) : 0;
+		ns->stack[ns->len++] = twig(t, i);
+	}
+	tkey_t *lkey = ns->stack[ns->len-1]->leaf.key;
+	// Find index of the first char that differs.
+	uint32_t index = 0;
+	while (index < MIN(len,lkey->len)) {
+		if (key[index] != lkey->chars[index])
+			break;
+		else
+			++index;
+	}
+	info->index = index;
+	if (first)
+		*first = lkey->len > index ? (unsigned char)lkey->chars[index] : -256;
+	// Find flags: which half-byte has matched.
+	uint flags;
+	if (index == len && len == lkey->len) { // found equivalent key
+		info->flags = flags = 0;
+		goto success;
+	}
+	if (likely(index < MIN(len,lkey->len))) {
+		byte k2 = (byte)lkey->chars[index];
+		byte k1 = (byte)key[index];
+		flags = ((k1 ^ k2) & 0xf0) ? 1 : 2;
+	} else { // one is prefix of another
+		flags = 1;
+	}
+	info->flags = flags;
+	// now go up the trie from the current leaf
+	branch_t *t;
+	do {
+		if (unlikely(ns->len == 1))
+			goto success; // only the root stays on the stack
+		t = (branch_t*)ns->stack[ns->len - 2];
+		if (t->index < index || (t->index == index && t->flags < flags))
+			goto success;
+		--ns->len;
+	} while (true);
+success:
+	#ifndef NDEBUG // invariants on successful return
+		assert(ns->len);
+		if (isbranch(ns->stack[ns->len - 1])) {
+			t = &ns->stack[ns->len - 1]->branch;
+			assert(t->index > index || (t->index == index && t->flags >= flags));
+		}
+		if (ns->len > 1) {
+			t = &ns->stack[ns->len - 2]->branch;
+			assert(t->index < index || (t->index == index
+			       && (t->flags < flags || (t->flags == 1 && flags == 0))));
+		}
+	#endif
+	return KNOT_EOK;
+}
+
+/*!
+ * \brief Advance the node stack to the last leaf in the subtree.
+ *
+ * \return KNOT_EOK or KNOT_ENOMEM.
+ */
+static int ns_last_leaf(nstack_t *ns)
+{
+	assert(ns);
+	do {
+		ERR_RETURN(ns_longer(ns));
+		node_t *t = ns->stack[ns->len - 1];
+		if (!isbranch(t))
+			return KNOT_EOK;
+		int lasti = bitmap_weight(t->branch.bitmap) - 1;
+		assert(lasti >= 0);
+		ns->stack[ns->len++] = twig(t, lasti);
+	} while (true);
+}
+
+/*!
+ * \brief Advance the node stack to the first leaf in the subtree.
+ *
+ * \return KNOT_EOK or KNOT_ENOMEM.
+ */
+static int ns_first_leaf(nstack_t *ns)
+{
+	assert(ns && ns->len);
+	do {
+		ERR_RETURN(ns_longer(ns));
+		node_t *t = ns->stack[ns->len - 1];
+		if (!isbranch(t))
+			return KNOT_EOK;
+		ns->stack[ns->len++] = twig(t, 0);
+	} while (true);
+}
+
+/*!
+ * \brief Advance the node stack to the leaf that is previous to the current node.
+ *
+ * \note Prefix leaf under the current node DOES count (if present; perhaps questionable).
+ * \return KNOT_EOK on success, KNOT_ENOENT on not-found, or possibly KNOT_ENOMEM.
+ */
+static int ns_prev_leaf(nstack_t *ns)
+{
+	assert(ns && ns->len > 0);
+
+	node_t *t = ns->stack[ns->len - 1];
+	if (hastwig(t, 1 << 0)) { // the prefix leaf
+		t = twig(t, 0);
+		ERR_RETURN(ns_longer(ns));
+		ns->stack[ns->len++] = t;
+		return KNOT_EOK;
+	}
+
+	do {
+		if (ns->len < 2)
+			return KNOT_ENOENT; // root without empty key has no previous leaf
+		t = ns->stack[ns->len - 1];
+		node_t *p = ns->stack[ns->len - 2];
+		int pindex = t - p->branch.twigs; // index in parent via pointer arithmetic
+		assert(pindex >= 0 && pindex <= 16);
+		if (pindex > 0) { // t isn't the first child -> go down the previous one
+			ns->stack[ns->len - 1] = twig(p, pindex - 1);
+			return ns_last_leaf(ns);
+		}
+		// we've got to go up again
+		--ns->len;
+	} while (true);
+}
+
+/*!
+ * \brief Advance the node stack to the leaf that is successor to the current node.
+ *
+ * \note Prefix leaf or anything else under the current node DOES count.
+ * \return KNOT_EOK on success, KNOT_ENOENT on not-found, or possibly KNOT_ENOMEM.
+ */
+static int ns_next_leaf(nstack_t *ns)
+{
+	assert(ns && ns->len > 0);
+
+	node_t *t = ns->stack[ns->len - 1];
+	if (isbranch(t))
+		return ns_first_leaf(ns);
+	do {
+		if (ns->len < 2)
+			return KNOT_ENOENT; // not found, as no more parent is available
+		t = ns->stack[ns->len - 1];
+		node_t *p = ns->stack[ns->len - 2];
+		int pindex = t - p->branch.twigs; // index in parent via pointer arithmetic
+		assert(pindex >= 0 && pindex <= 16);
+		int pcount = bitmap_weight(p->branch.bitmap);
+		if (pindex + 1 < pcount) { // t isn't the last child -> go down the next one
+			ns->stack[ns->len - 1] = twig(p, pindex + 1);
+			return ns_first_leaf(ns);
+		}
+		// we've got to go up again
+		--ns->len;
+	} while (true);
+}
+
+int trie_get_leq(trie_t *tbl, const char *key, uint32_t len, trie_val_t **val)
+{
+	assert(tbl && val);
+	*val = NULL; // so on failure we can just return;
+	if (tbl->weight == 0)
+		return KNOT_ENOENT;
+	{ // Intentionally un-indented; until end of function, to bound cleanup attr.
+	// First find a key with longest-matching prefix
+	__attribute__((cleanup(ns_cleanup)))
+		nstack_t ns_local;
+	ns_init(&ns_local, tbl);
+	nstack_t *ns = &ns_local;
+	branch_t bp;
+	int un_leaf; // first unmatched character in the leaf
+	ERR_RETURN(ns_find_branch(ns, key, len, &bp, &un_leaf));
+	int un_key = bp.index < len ? (unsigned char)key[bp.index] : -256;
+	node_t *t = ns->stack[ns->len - 1];
+	if (bp.flags == 0) { // found exact match
+		*val = &t->leaf.val;
+		return KNOT_EOK;
+	}
+	// Get t: the last node on matching path
+	if (isbranch(t) && t->branch.index == bp.index && t->branch.flags == bp.flags) {
+		// t is OK
+	} else {
+		// the top of the stack was the first unmatched node -> step up
+		if (ns->len == 1) {
+			// root was unmatched already
+			if (un_key < un_leaf)
+				return KNOT_ENOENT;
+			ERR_RETURN(ns_last_leaf(ns));
+			goto success;
+		}
+		--ns->len;
+		t = ns->stack[ns->len - 1];
+	}
+	// Now we re-do the first "non-matching" step in the trie
+	// but try the previous child if key was less (it may not exist)
+	bitmap_t b = twigbit(t, key, len);
+	int i = hastwig(t, b)
+		? twigoff(t, b) - (un_key < un_leaf)
+		: twigoff(t, b) - 1 /*twigoff returns successor when !hastwig*/;
+	if (i >= 0) {
+		ERR_RETURN(ns_longer(ns));
+		ns->stack[ns->len++] = twig(t, i);
+		ERR_RETURN(ns_last_leaf(ns));
+	} else {
+		ERR_RETURN(ns_prev_leaf(ns));
+	}
+success:
+	assert(!isbranch(ns->stack[ns->len - 1]));
+	*val = &ns->stack[ns->len - 1]->leaf.val;
+	return 1;
+	}
+}
+
+/*! \brief Initialize a new leaf, copying the key, and returning failure code. */
+static int mk_leaf(node_t *leaf, const char *key, uint32_t len, knot_mm_t *mm)
+{
+	tkey_t *k = mm_alloc(mm, sizeof(tkey_t) + len);
+	#if FLAGS_HACK
+		assert(((uintptr_t)k) % 4 == 0); // we need an aligned pointer
+	#endif
+	if (unlikely(!k))
+		return KNOT_ENOMEM;
+	k->len = len;
+	memcpy(k->chars, key, len);
+	leaf->leaf = (leaf_t){
+		#if !FLAGS_HACK
+			.flags = 0,
+		#endif
+		.val = NULL,
+		.key = k
+	};
+	return KNOT_EOK;
+}
+
+trie_val_t* trie_get_ins(trie_t *tbl, const char *key, uint32_t len)
+{
+	assert(tbl);
+	// First leaf in an empty tbl?
+	if (unlikely(!tbl->weight)) {
+		if (unlikely(mk_leaf(&tbl->root, key, len, &tbl->mm)))
+			return NULL;
+		++tbl->weight;
+		return &tbl->root.leaf.val;
+	}
+	{ // Intentionally un-indented; until end of function, to bound cleanup attr.
+	// Find the branching-point
+	__attribute__((cleanup(ns_cleanup)))
+		nstack_t ns_local;
+	ns_init(&ns_local, tbl);
+	nstack_t *ns = &ns_local;
+	branch_t bp; // branch-point: index and flags signifying the longest common prefix
+	int k2; // the first unmatched character in the leaf
+	if (unlikely(ns_find_branch(ns, key, len, &bp, &k2)))
+		return NULL;
+	node_t *t = ns->stack[ns->len - 1];
+	if (bp.flags == 0) // the same key was already present
+		return &t->leaf.val;
+	node_t leaf;
+	if (unlikely(mk_leaf(&leaf, key, len, &tbl->mm)))
+		return NULL;
+
+	if (isbranch(t) && bp.index == t->branch.index && bp.flags == t->branch.flags) {
+		// The node t needs a new leaf child.
+		bitmap_t b1 = twigbit(t, key, len);
+		assert(!hastwig(t, b1));
+		uint s, m; TWIGOFFMAX(s, m, t, b1); // new child position and original child count
+		node_t *twigs = mm_realloc(&tbl->mm, t->branch.twigs,
+				sizeof(node_t) * (m + 1), sizeof(node_t) * m);
+		if (unlikely(!twigs))
+			goto err_leaf;
+		memmove(twigs + s + 1, twigs + s, sizeof(node_t) * (m - s));
+		twigs[s] = leaf;
+		t->branch.twigs = twigs;
+		t->branch.bitmap |= b1;
+		++tbl->weight;
+		return &twigs[s].leaf.val;
+	} else {
+		// We need to insert a new binary branch with leaf at *t.
+		// Note: it works the same for the case where we insert above root t.
+		#ifndef NDEBUG
+			if (ns->len > 1) {
+				node_t *pt = ns->stack[ns->len - 2];
+				assert(hastwig(pt, twigbit(pt, key, len)));
+			}
+		#endif
+		node_t *twigs = mm_alloc(&tbl->mm, sizeof(node_t) * 2);
+		if (unlikely(!twigs))
+			goto err_leaf;
+		node_t t2 = *t; // Save before overwriting t.
+		t->branch.flags = bp.flags;
+		t->branch.index = bp.index;
+		t->branch.twigs = twigs;
+		bitmap_t b1 = twigbit(t, key, len);
+		bitmap_t b2 = unlikely(k2 == -256) ? (1 << 0) : nibbit(k2, bp.flags);
+		t->branch.bitmap = b1 | b2;
+		*twig(t, twigoff(t, b1)) = leaf;
+		*twig(t, twigoff(t, b2)) = t2;
+		++tbl->weight;
+		return &twig(t, twigoff(t, b1))->leaf.val;
+	};
+err_leaf:
+	mm_free(&tbl->mm, leaf.leaf.key);
+	return NULL;
+	}
+}
+
+/*! \brief Apply a function to every trie_val_t*, in order; a recursive solution. */
+static int apply_trie(node_t *t, int (*f)(trie_val_t *, void *), void *d)
+{
+	assert(t);
+	if (!isbranch(t))
+		return f(&t->leaf.val, d);
+	int child_count = bitmap_weight(t->branch.bitmap);
+	for (int i = 0; i < child_count; ++i)
+		ERR_RETURN(apply_trie(twig(t, i), f, d));
+	return KNOT_EOK;
+}
+
+int trie_apply(trie_t *tbl, int (*f)(trie_val_t *, void *), void *d)
+{
+	assert(tbl && f);
+	if (!tbl->weight)
+		return KNOT_EOK;
+	return apply_trie(&tbl->root, f, d);
+}
+
+/* These are all thin wrappers around static Tns* functions. */
+trie_it_t* trie_it_begin(trie_t *tbl)
+{
+	assert(tbl);
+	trie_it_t *it = malloc(sizeof(nstack_t));
+	if (!it)
+		return NULL;
+	ns_init(it, tbl);
+	if (it->len == 0) // empty tbl
+		return it;
+	if (ns_first_leaf(it)) {
+		ns_cleanup(it);
+		free(it);
+		return NULL;
+	}
+	return it;
+}
+
+void trie_it_next(trie_it_t *it)
+{
+	assert(it && it->len);
+	if (ns_next_leaf(it) != KNOT_EOK)
+		it->len = 0;
+}
+
+bool trie_it_finished(trie_it_t *it)
+{
+	assert(it);
+	return it->len == 0;
+}
+
+void trie_it_free(trie_it_t *it)
+{
+	if (!it)
+		return;
+	ns_cleanup(it);
+	free(it);
+}
+
+const char* trie_it_key(trie_it_t *it, size_t *len)
+{
+	assert(it && it->len);
+	node_t *t = it->stack[it->len - 1];
+	assert(!isbranch(t));
+	tkey_t *key = t->leaf.key;
+	if (len)
+		*len = key->len;
+	return key->chars;
+}
+
+trie_val_t* trie_it_val(trie_it_t *it)
+{
+	assert(it && it->len);
+	node_t *t = it->stack[it->len - 1];
+	assert(!isbranch(t));
+	return &t->leaf.val;
+}
diff --git a/lib/generic/trie.h b/lib/generic/trie.h
new file mode 100644
index 0000000..dd9d3eb
--- /dev/null
+++ b/lib/generic/trie.h
@@ -0,0 +1,139 @@
+/*  Copyright (C) 2017-2018 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#pragma once
+
+#include <stdbool.h>
+#include <stdint.h>
+
+#include <libknot/mm_ctx.h>
+#include "lib/defines.h"
+
+/*!
+ * \brief Native API of QP-tries:
+ *
+ * - keys are char strings, not necessarily zero-terminated,
+ *   the structure copies the contents of the passed keys
+ * - values are void* pointers, typically you get an ephemeral pointer to it
+ * - key lengths are limited by 2^32-1 ATM
+ *
+ * XXX EDITORS: trie.{h,c} are synced from
+ * https://gitlab.nic.cz/knot/knot-dns/tree/68352fc969/src/contrib/qp-trie
+ * only with tiny adjustments, mostly include lines and KR_EXPORT.
+ */
+
+/*! \brief Element value. */
+typedef void* trie_val_t;
+
+/*! \brief Opaque structure holding a QP-trie. */
+typedef struct trie trie_t;
+
+/*! \brief Opaque type for holding a QP-trie iterator. */
+typedef struct trie_it trie_it_t;
+
+/*! \brief Create a trie instance.  Pass NULL to use malloc+free. */
+KR_EXPORT
+trie_t* trie_create(knot_mm_t *mm);
+
+/*! \brief Free a trie instance. */
+KR_EXPORT
+void trie_free(trie_t *tbl);
+
+/*! \brief Clear a trie instance (make it empty). */
+KR_EXPORT
+void trie_clear(trie_t *tbl);
+
+/*! \brief Return the number of keys in the trie. */
+KR_EXPORT
+size_t trie_weight(const trie_t *tbl);
+
+/*! \brief Search the trie, returning NULL on failure. */
+KR_EXPORT
+trie_val_t* trie_get_try(trie_t *tbl, const char *key, uint32_t len);
+
+/*!
+ * \brief Return pointer to the minimum.  Optionally with key and its length. */
+KR_EXPORT
+trie_val_t* trie_get_first(trie_t *tbl, char **key, uint32_t *len);
+
+/*! \brief Search the trie, inserting NULL trie_val_t on failure. */
+KR_EXPORT
+trie_val_t* trie_get_ins(trie_t *tbl, const char *key, uint32_t len);
+
+/*!
+ * \brief Search for less-or-equal element.
+ *
+ * \param tbl  Trie.
+ * \param key  Searched key.
+ * \param len  Key length.
+ * \param val  Must be valid; it will be set to NULL if not found or errored.
+ * \return KNOT_EOK for exact match, 1 for previous, KNOT_ENOENT for not-found,
+ *         or KNOT_E*.
+ */
+KR_EXPORT
+int trie_get_leq(trie_t *tbl, const char *key, uint32_t len, trie_val_t **val);
+
+/*!
+ * \brief Apply a function to every trie_val_t, in order.
+ *
+ * \param d Parameter passed as the second argument to f().
+ * \return First nonzero from f() or zero (i.e. KNOT_EOK).
+ */
+KR_EXPORT
+int trie_apply(trie_t *tbl, int (*f)(trie_val_t *, void *), void *d);
+
+/*!
+ * \brief Remove an item, returning KNOT_EOK if succeeded or KNOT_ENOENT if not found.
+ *
+ * If val!=NULL and deletion succeeded, the deleted value is set.
+ */
+KR_EXPORT
+int trie_del(trie_t *tbl, const char *key, uint32_t len, trie_val_t *val);
+
+/*!
+ * \brief Remove the first item, returning KNOT_EOK on success.
+ *
+ * You may optionally get the key and/or value.
+ * The key is copied, so you need to pass sufficient len,
+ * otherwise kr_error(ENOSPC) is returned.
+ */
+KR_EXPORT
+int trie_del_first(trie_t *tbl, char *key, uint32_t *len, trie_val_t *val);
+
+/*! \brief Create a new iterator pointing to the first element (if any). */
+KR_EXPORT
+trie_it_t* trie_it_begin(trie_t *tbl);
+
+/*!
+ * \brief Advance the iterator to the next element.
+ *
+ * Iteration is in ascending lexicographical order.
+ * In particular, the empty string would be considered as the very first.
+ *
+ * \note You may not use this function if the trie's key-set has been modified
+ * during the lifetime of the iterator (modifying values only is OK).
+ */
+KR_EXPORT
+void trie_it_next(trie_it_t *it);
+
+/*! \brief Test if the iterator has gone past the last element. */
+KR_EXPORT
+bool trie_it_finished(trie_it_t *it);
+
+/*! \brief Free any resources of the iterator. It's OK to call it on NULL. */
+KR_EXPORT
+void trie_it_free(trie_it_t *it);
+
+/*!
+ * \brief Return pointer to the key of the current element.
+ *
+ * \note The optional len is uint32_t internally but size_t is better for our usage,
+ *       as it is without an additional type conversion.
+ */
+KR_EXPORT
+const char* trie_it_key(trie_it_t *it, size_t *len);
+
+/*! \brief Return pointer to the value of the current element (writable). */
+KR_EXPORT
+trie_val_t* trie_it_val(trie_it_t *it);
diff --git a/lib/generic/trie.spdx b/lib/generic/trie.spdx
new file mode 100644
index 0000000..e8d52f2
--- /dev/null
+++ b/lib/generic/trie.spdx
@@ -0,0 +1,10 @@
+SPDXVersion: SPDX-2.1
+DataLicense: CC0-1.0
+SPDXID: SPDXRef-DOCUMENT
+DocumentName: knotdns-trie
+DocumentNamespace: http://spdx.org/spdxdocs/spdx-v2.1-f99c0e11-6afb-46ce-af96-0955a83957bb
+
+PackageName: knotdns-trie
+PackageDownloadLocation: git+https://gitlab.nic.cz/knot/knot-dns.git@68352fc969bc04aa4aa8203e113ce747d887f410#src/contrib/qp-trie/trie.c
+PackageOriginator: Organization: Knot DNS contributors
+PackageLicenseDeclared: GPL-3.0-or-later
diff --git a/lib/layer.h b/lib/layer.h
new file mode 100644
index 0000000..6381244
--- /dev/null
+++ b/lib/layer.h
@@ -0,0 +1,122 @@
+/*  Copyright (C) 2014-2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#pragma once
+
+#include "kresconfig.h"
+#include "lib/defines.h"
+#include "lib/utils.h"
+
+#ifdef NOVERBOSELOG
+	#define QRVERBOSE(query, cls, ...)
+#else
+	/** Print a debug message related to resolution.
+	 * \param _query	associated kr_query, may be NULL
+	 * \param _cls	identifying string, typically of length exactly four (padded)
+	 * \param ...	printf-compatible list of parameters
+	 */
+	#define QRVERBOSE(_query, _cls, ...) do { \
+		const struct kr_query *_qry = (_query); \
+		if (VERBOSE_STATUS || kr_log_qtrace_enabled(_qry)) { \
+			kr_log_q(_qry, (_cls), __VA_ARGS__); \
+		}  \
+	} while (false)
+#endif
+
+/** Layer processing states.  Only one value at a time (but see TODO).
+ *
+ *  Each state represents the state machine transition,
+ *  and determines readiness for the next action.
+ *  See struct kr_layer_api for the actions.
+ *
+ *  TODO: the cookie module sometimes sets (_FAIL | _DONE) on purpose (!)
+ */
+enum kr_layer_state {
+	KR_STATE_CONSUME = 1 << 0, /*!< Consume data. */
+	KR_STATE_PRODUCE = 1 << 1, /*!< Produce data. */
+
+	/*! Finished successfully or a special case: in CONSUME phase this can
+	 * be used (by iterator) to do a transition to PRODUCE phase again,
+	 * in which case the packet wasn't accepted for some reason. */
+	KR_STATE_DONE    = 1 << 2,
+
+	KR_STATE_FAIL    = 1 << 3, /*!< Error. */
+	KR_STATE_YIELD   = 1 << 4, /*!< Paused, waiting for a sub-query. */
+};
+
+/** Check that a kr_layer_state makes sense.  We're not very strict ATM. */
+static inline bool kr_state_consistent(enum kr_layer_state s)
+{
+#ifdef __clang__
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wtautological-constant-out-of-range-compare"
+#endif
+	return s >= 0 && s < (1 << 5);
+#ifdef __clang__
+#pragma clang diagnostic pop
+#endif
+}
+
+/* Forward declarations. */
+struct kr_layer_api;
+
+/** Packet processing context. */
+typedef struct kr_layer {
+	int state; /*!< The current state; bitmap of enum kr_layer_state. */
+	struct kr_request *req; /*!< The corresponding request. */
+	const struct kr_layer_api *api;
+	knot_pkt_t *pkt; /*!< In glue for lua kr_layer_api it's used to pass the parameter. */
+	struct sockaddr *dst; /*!< In glue for checkout layer it's used to pass the parameter. */
+	bool is_stream;       /*!< In glue for checkout layer it's used to pass the parameter. */
+} kr_layer_t;
+
+/** Packet processing module API.  All functions return the new kr_layer_state.
+ *
+ * Lua modules are allowed to return nil/nothing, meaning the state shall not change.
+ */
+struct kr_layer_api {
+      	/** Start of processing the DNS request. */
+	int (*begin)(kr_layer_t *ctx);
+
+	int (*reset)(kr_layer_t *ctx);
+
+	/** Paired to begin, called both on successes and failures. */
+	int (*finish)(kr_layer_t *ctx);
+
+	/** Process an answer from upstream or from cache.
+	 * Lua API: call is omitted iff (state & KR_STATE_FAIL). */
+	int (*consume)(kr_layer_t *ctx, knot_pkt_t *pkt);
+
+	/** Produce either an answer to the request or a query for upstream (or fail).
+	 * Lua API: call is omitted iff (state & KR_STATE_FAIL). */
+	int (*produce)(kr_layer_t *ctx, knot_pkt_t *pkt);
+
+	/** Finalises the outbound query packet with the knowledge of the IP addresses.
+	 * The checkout layer doesn't persist the state, so canceled subrequests
+	 * don't affect the resolution or rest of the processing.
+	 * Lua API: call is omitted iff (state & KR_STATE_FAIL). */
+	int (*checkout)(kr_layer_t *ctx, knot_pkt_t *packet, struct sockaddr *dst, int type);
+
+	/** Finalises the answer.
+	 * Last chance to affect what will get into the answer, including EDNS.
+	 * Not called if the packet is being dropped. */
+	int (*answer_finalize)(kr_layer_t *ctx);
+
+	/** The C module can store anything in here. */
+	void *data;
+
+	/** Internal to ./daemon/ffimodule.c. */
+	int cb_slots[];
+};
+
+typedef struct kr_layer_api kr_layer_api_t;
+
+/** Pickled layer state (api, input, state). */
+struct kr_layer_pickle {
+    struct kr_layer_pickle *next;
+    const struct kr_layer_api *api;
+    knot_pkt_t *pkt;
+    unsigned state;
+};
+
diff --git a/lib/layer/cache.c b/lib/layer/cache.c
new file mode 100644
index 0000000..a532efd
--- /dev/null
+++ b/lib/layer/cache.c
@@ -0,0 +1,20 @@
+/*  Copyright (C) 2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#include "lib/module.h"
+#include "lib/cache/api.h"
+
+/** Module implementation. */
+int cache_init(struct kr_module *self)
+{
+	static const kr_layer_api_t layer = {
+		.produce = &cache_peek,
+		.consume = &cache_stash,
+	};
+	self->layer = &layer;
+	return kr_ok();
+}
+
+KR_MODULE_EXPORT(cache) /* useless for builtin module, but let's be consistent */
+
diff --git a/lib/layer/iterate.c b/lib/layer/iterate.c
new file mode 100644
index 0000000..94342cf
--- /dev/null
+++ b/lib/layer/iterate.c
@@ -0,0 +1,1186 @@
+/*  Copyright (C) 2014-2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+/** @file iterate.c
+ *
+ * This builtin module is mainly active in the consume phase.
+ * Primary responsibilities:
+ *  - Classify the packet as auth/nonauth and change its AA flag accordingly.
+ *  - Pick interesting RRs to kr_request::answ_selected and ::auth_selected,
+ *    NEW: and classify their rank, except for validation status.
+ *  - Update kr_query::zone_cut (in case of referral).
+ *  - Interpret CNAMEs.
+ *  - Prepare the followup query - either inline or as another kr_query
+ *    (CNAME jumps create a new "sibling" query).
+ */
+
+#include <sys/time.h>
+#include <assert.h>
+#include <arpa/inet.h>
+
+#include <contrib/cleanup.h>
+#include <libknot/descriptor.h>
+#include <libknot/rrtype/rdname.h>
+#include <libknot/rrtype/rrsig.h>
+
+#include "kresconfig.h"
+#include "lib/layer/iterate.h"
+#include "lib/resolve.h"
+#include "lib/rplan.h"
+#include "lib/defines.h"
+#include "lib/selection.h"
+#include "lib/module.h"
+#include "lib/dnssec/ta.h"
+
+#define VERBOSE_MSG(...) QRVERBOSE(req->current_query, "iter", __VA_ARGS__)
+#define QVERBOSE_MSG(qry, ...) QRVERBOSE(qry, "iter", __VA_ARGS__)
+
+/* Iterator often walks through packet section, this is an abstraction. */
+typedef int (*rr_callback_t)(const knot_rrset_t *, unsigned, struct kr_request *);
+
+/** Return minimized QNAME/QTYPE for current zone cut. */
+static const knot_dname_t *minimized_qname(struct kr_query *query, uint16_t *qtype)
+{
+	/* Minimization disabled. */
+	const knot_dname_t *qname = query->sname;
+	if (qname[0] == '\0' || query->flags.NO_MINIMIZE || query->flags.STUB) {
+		return qname;
+	}
+
+	/* Minimize name to contain current zone cut + 1 label. */
+	int cut_labels = knot_dname_labels(query->zone_cut.name, NULL);
+	int qname_labels = knot_dname_labels(qname, NULL);
+	while(qname[0] && qname_labels > cut_labels + 1) {
+		qname = knot_wire_next_label(qname, NULL);
+		qname_labels -= 1;
+	}
+
+	/* Hide QTYPE if minimized. */
+	if (qname != query->sname) {
+		*qtype = KNOT_RRTYPE_NS;
+	}
+
+	return qname;
+}
+
+/** Answer is paired to query. */
+static bool is_paired_to_query(const knot_pkt_t *answer, struct kr_query *query)
+{
+	uint16_t qtype = query->stype;
+	const knot_dname_t *qname = minimized_qname(query, &qtype);
+
+	/* ID should already match, thanks to session_tasklist_del_msgid()
+	 * in worker_submit(), but it won't hurt to check again. */
+	return query->id      == knot_wire_get_id(answer->wire) &&
+	       knot_wire_get_qdcount(answer->wire) == 1 &&
+	       query->sclass  == knot_pkt_qclass(answer) &&
+	       qtype          == knot_pkt_qtype(answer) &&
+	       /* qry->secret had been xor-applied to answer already,
+		* so this also checks for correctness of case randomization */
+	       knot_dname_is_equal(qname, knot_pkt_qname(answer));
+}
+
+/** Relaxed rule for AA, either AA=1 or SOA matching zone cut is required. */
+static bool is_authoritative(const knot_pkt_t *answer, struct kr_query *query)
+{
+	if (knot_wire_get_aa(answer->wire)) {
+		return true;
+	}
+
+	const knot_pktsection_t *ns = knot_pkt_section(answer, KNOT_AUTHORITY);
+	for (unsigned i = 0; i < ns->count; ++i) {
+		const knot_rrset_t *rr = knot_pkt_rr(ns, i);
+		if (rr->type == KNOT_RRTYPE_SOA
+		    && knot_dname_in_bailiwick(rr->owner, query->zone_cut.name) >= 0) {
+			return true;
+		}
+	}
+
+#ifndef STRICT_MODE
+	/* Last resort to work around broken auths, if the zone cut is at the QNAME. */
+	if (knot_dname_is_equal(query->zone_cut.name, knot_pkt_qname(answer))) {
+		return true;
+	}
+#endif
+
+	/* Some authoritative servers are hopelessly broken, allow lame answers in permissive mode. */
+	if (query->flags.PERMISSIVE) {
+		return true;
+	}
+
+	return false;
+}
+
+int kr_response_classify(const knot_pkt_t *pkt)
+{
+	const knot_pktsection_t *an = knot_pkt_section(pkt, KNOT_ANSWER);
+	switch (knot_wire_get_rcode(pkt->wire)) {
+	case KNOT_RCODE_NOERROR:
+		return (an->count == 0) ? PKT_NODATA : PKT_NOERROR;
+	case KNOT_RCODE_NXDOMAIN:
+		return PKT_NXDOMAIN;
+	case KNOT_RCODE_REFUSED:
+		return PKT_REFUSED;
+	default:
+		return PKT_ERROR;
+	}
+}
+
+/** @internal Filter ANY or loopback addresses. */
+static bool is_valid_addr(const uint8_t *addr, size_t len)
+{
+	if (len == sizeof(struct in_addr)) {
+		/* Filter ANY and 127.0.0.0/8 */
+		uint32_t ip_host = ntohl(*(const uint32_t *)(addr));
+		if (ip_host == 0 || (ip_host & 0xff000000) == 0x7f000000) {
+			return false;
+		}
+	} else if (len == sizeof(struct in6_addr)) {
+		struct in6_addr ip6_mask;
+		memset(&ip6_mask, 0, sizeof(ip6_mask));
+		/* All except last byte are zeroed, last byte defines ANY/::1 */
+		if (memcmp(addr, ip6_mask.s6_addr, sizeof(ip6_mask.s6_addr) - 1) == 0) {
+			return (addr[len - 1] > 1);
+		}
+	}
+	return true;
+}
+
+/** @internal Update NS address from record \a rr.  Return _FAIL on error. */
+static int update_nsaddr(const knot_rrset_t *rr, struct kr_query *query, int *glue_cnt)
+{
+	if (rr->type == KNOT_RRTYPE_A || rr->type == KNOT_RRTYPE_AAAA) {
+		const knot_rdata_t *rdata = rr->rrs.rdata;
+		const int a_len = rr->type == KNOT_RRTYPE_A
+			? sizeof(struct in_addr) : sizeof(struct in6_addr);
+		if (a_len != rdata->len) {
+			QVERBOSE_MSG(query, "<= ignoring invalid glue, length %d != %d\n",
+					(int)rdata->len, a_len);
+			return KR_STATE_FAIL;
+		}
+		char name_str[KR_DNAME_STR_MAXLEN];
+		char addr_str[INET6_ADDRSTRLEN];
+		WITH_VERBOSE(query) {
+			const int af = (rr->type == KNOT_RRTYPE_A) ? AF_INET : AF_INET6;
+			knot_dname_to_str(name_str, rr->owner, sizeof(name_str));
+			name_str[sizeof(name_str) - 1] = 0;
+			inet_ntop(af, rdata->data, addr_str, sizeof(addr_str));
+		}
+		if (!(query->flags.ALLOW_LOCAL) &&
+			!is_valid_addr(rdata->data, rdata->len)) {
+			QVERBOSE_MSG(query, "<= ignoring invalid glue for "
+				     "'%s': '%s'\n", name_str, addr_str);
+			return KR_STATE_CONSUME; /* Ignore invalid addresses */
+		}
+		int ret = kr_zonecut_add(&query->zone_cut, rr->owner, rdata->data, rdata->len);
+		if (ret != 0) {
+			return KR_STATE_FAIL;
+		}
+
+		++*glue_cnt; /* reduced verbosity */
+		/* QVERBOSE_MSG(query, "<= using glue for "
+			     "'%s': '%s'\n", name_str, addr_str);
+		*/
+	}
+	return KR_STATE_CONSUME;
+}
+
+/** @internal From \a pkt, fetch glue records for name \a ns, and update the cut etc.
+ *
+ * \param glue_cnt the number of accepted addresses (to be incremented)
+ */
+static void fetch_glue(knot_pkt_t *pkt, const knot_dname_t *ns, bool in_bailiwick,
+			struct kr_request *req, const struct kr_query *qry, int *glue_cnt)
+{
+	ranked_rr_array_t *selected[] = kr_request_selected(req);
+	for (knot_section_t i = KNOT_ANSWER; i <= KNOT_ADDITIONAL; ++i) {
+		const knot_pktsection_t *sec = knot_pkt_section(pkt, i);
+		for (unsigned k = 0; k < sec->count; ++k) {
+			const knot_rrset_t *rr = knot_pkt_rr(sec, k);
+			if (!knot_dname_is_equal(ns, rr->owner)) {
+				continue;
+			}
+			if ((rr->type != KNOT_RRTYPE_A) &&
+			    (rr->type != KNOT_RRTYPE_AAAA)) {
+				continue;
+			}
+
+			uint8_t rank = (in_bailiwick && i == KNOT_ANSWER)
+				? (KR_RANK_INITIAL | KR_RANK_AUTH) : KR_RANK_OMIT;
+			(void) kr_ranked_rrarray_add(selected[i], rr, rank,
+							false, qry->uid, &req->pool);
+
+			if ((rr->type == KNOT_RRTYPE_A) &&
+			    (req->ctx->options.NO_IPV4)) {
+				QVERBOSE_MSG(qry, "<= skipping IPv4 glue due to network settings\n");
+				continue;
+			}
+			if ((rr->type == KNOT_RRTYPE_AAAA) &&
+			    (req->ctx->options.NO_IPV6)) {
+				QVERBOSE_MSG(qry, "<= skipping IPv6 glue due to network settings\n");
+				continue;
+			}
+			(void) update_nsaddr(rr, req->current_query, glue_cnt);
+		}
+	}
+}
+
+/** Attempt to find glue for given nameserver name (best effort). */
+static bool has_glue(knot_pkt_t *pkt, const knot_dname_t *ns)
+{
+	for (knot_section_t i = KNOT_ANSWER; i <= KNOT_ADDITIONAL; ++i) {
+		const knot_pktsection_t *sec = knot_pkt_section(pkt, i);
+		for (unsigned k = 0; k < sec->count; ++k) {
+			const knot_rrset_t *rr = knot_pkt_rr(sec, k);
+			if (knot_dname_is_equal(ns, rr->owner) &&
+			    (rr->type == KNOT_RRTYPE_A || rr->type == KNOT_RRTYPE_AAAA)) {
+				return true;
+			}
+		}
+	}
+	return false;
+}
+
+/** @internal Update the cut with another NS(+glue) record.
+ * @param current_cut is cut name before this packet.
+ * @return _DONE if cut->name changes, _FAIL on error, and _CONSUME otherwise. */
+static int update_cut(knot_pkt_t *pkt, const knot_rrset_t *rr,
+		      struct kr_request *req, const knot_dname_t *current_cut,
+		      int *glue_cnt)
+{
+	struct kr_query *qry = req->current_query;
+	struct kr_zonecut *cut = &qry->zone_cut;
+	int state = KR_STATE_CONSUME;
+
+	/* New authority MUST be at/below the authority of the current cut;
+	 * also qname must be below new authority;
+	 * otherwise it's a possible cache injection attempt. */
+	const bool ok = knot_dname_in_bailiwick(rr->owner, current_cut) >= 0
+		     && knot_dname_in_bailiwick(qry->sname, rr->owner)  >= 0;
+	if (!ok) {
+		VERBOSE_MSG("<= authority: ns outside bailiwick\n");
+		qry->server_selection.error(qry, req->upstream.transport, KR_SELECTION_LAME_DELEGATION);
+#ifdef STRICT_MODE
+		return KR_STATE_FAIL;
+#else
+		/* Workaround: ignore out-of-bailiwick NSs for authoritative answers,
+		 * but fail for referrals. This is important to detect lame answers. */
+		if (knot_pkt_section(pkt, KNOT_ANSWER)->count == 0) {
+			state = KR_STATE_FAIL;
+		}
+		return state;
+#endif
+	}
+
+	/* Update zone cut name */
+	if (!knot_dname_is_equal(rr->owner, cut->name)) {
+		/* Remember parent cut and descend to new (keep keys and TA). */
+		struct kr_zonecut *parent = mm_alloc(&req->pool, sizeof(*parent));
+		if (parent) {
+			memcpy(parent, cut, sizeof(*parent));
+			kr_zonecut_init(cut, rr->owner, &req->pool);
+			cut->key = parent->key;
+			cut->trust_anchor = parent->trust_anchor;
+			cut->parent = parent;
+		} else {
+			kr_zonecut_set(cut, rr->owner);
+		}
+		state = KR_STATE_DONE;
+	}
+
+	/* Fetch glue for each NS */
+	knot_rdata_t *rdata_i = rr->rrs.rdata;
+	for (unsigned i = 0; i < rr->rrs.count;
+			++i, rdata_i = knot_rdataset_next(rdata_i)) {
+		const knot_dname_t *ns_name = knot_ns_name(rdata_i);
+		/* Glue is mandatory for NS below zone */
+		if (knot_dname_in_bailiwick(ns_name, rr->owner) >= 0
+		    && !has_glue(pkt, ns_name)) {
+			const char *msg =
+				"<= authority: missing mandatory glue, skipping NS";
+			WITH_VERBOSE(qry) {
+				auto_free char *ns_str = kr_dname_text(ns_name);
+				VERBOSE_MSG("%s %s\n", msg, ns_str);
+			}
+			continue;
+		}
+		int ret = kr_zonecut_add(cut, ns_name, NULL, 0);
+		assert(!ret); (void)ret;
+
+		/* Choose when to use glue records. */
+		const bool in_bailiwick =
+			knot_dname_in_bailiwick(ns_name, current_cut) >= 0;
+		bool do_fetch;
+		if (qry->flags.PERMISSIVE) {
+			do_fetch = true;
+		} else if (qry->flags.STRICT) {
+			/* Strict mode uses only mandatory glue. */
+			do_fetch = knot_dname_in_bailiwick(ns_name, cut->name) >= 0;
+		} else {
+			/* Normal mode uses in-bailiwick glue. */
+			do_fetch = in_bailiwick;
+		}
+		if (do_fetch) {
+			fetch_glue(pkt, ns_name, in_bailiwick, req, qry, glue_cnt);
+		}
+	}
+
+	return state;
+}
+
+/** Compute rank appropriate for RRs present in the packet.
+ * @param answer whether the RR is from answer or authority section
+ * @param is_nonauth: from referral or forwarding (etc.) */
+static uint8_t get_initial_rank(const knot_rrset_t *rr, const struct kr_query *qry,
+				const bool answer, const bool is_nonauth)
+{
+	/* For RRSIGs, ensure the KR_RANK_AUTH flag corresponds to the signed RR. */
+	uint16_t type = kr_rrset_type_maysig(rr);
+
+	if (qry->flags.CACHED) {
+		return rr->additional ? *(uint8_t *)rr->additional : KR_RANK_OMIT;
+		/* ^^ Current use case for "cached" RRs without rank: hints module. */
+	}
+	if (answer || type == KNOT_RRTYPE_DS
+	    || type == KNOT_RRTYPE_SOA /* needed for aggressive negative caching */
+	    || type == KNOT_RRTYPE_NSEC || type == KNOT_RRTYPE_NSEC3) {
+		/* We almost always want these validated, and it should be possible. */
+		return KR_RANK_INITIAL | KR_RANK_AUTH;
+	}
+	/* Be aggressive: try to validate anything else (almost never extra latency). */
+	return KR_RANK_TRY;
+	/* TODO: this classifier of authoritativity may not be perfect yet. */
+}
+
+static int pick_authority(knot_pkt_t *pkt, struct kr_request *req, bool to_wire)
+{
+	struct kr_query *qry = req->current_query;
+	const knot_pktsection_t *ns = knot_pkt_section(pkt, KNOT_AUTHORITY);
+
+	const knot_dname_t *zonecut_name = qry->zone_cut.name;
+	bool referral = !knot_wire_get_aa(pkt->wire);
+	if (referral) {
+		/* zone cut already updated by process_authority()
+		 * use parent zonecut name */
+		zonecut_name = qry->zone_cut.parent ? qry->zone_cut.parent->name : qry->zone_cut.name;
+		to_wire = false;
+	}
+
+	for (unsigned i = 0; i < ns->count; ++i) {
+		const knot_rrset_t *rr = knot_pkt_rr(ns, i);
+		if (rr->rclass != KNOT_CLASS_IN
+		    || knot_dname_in_bailiwick(rr->owner, zonecut_name) < 0) {
+			continue;
+		}
+		uint8_t rank = get_initial_rank(rr, qry, false,
+						qry->flags.FORWARD || referral);
+		int ret = kr_ranked_rrarray_add(&req->auth_selected, rr,
+						rank, to_wire, qry->uid, &req->pool);
+		if (ret < 0) {
+			return ret;
+		}
+	}
+
+	return kr_ok();
+}
+
+static int process_authority(knot_pkt_t *pkt, struct kr_request *req)
+{
+	struct kr_query *qry = req->current_query;
+	assert(!(qry->flags.STUB));
+
+	int result = KR_STATE_CONSUME;
+	if (qry->flags.FORWARD) {
+		return result;
+	}
+
+	const knot_pktsection_t *ns = knot_pkt_section(pkt, KNOT_AUTHORITY);
+	const knot_pktsection_t *an = knot_pkt_section(pkt, KNOT_ANSWER);
+
+#ifdef STRICT_MODE
+	/* AA, terminate resolution chain. */
+	if (knot_wire_get_aa(pkt->wire)) {
+		return KR_STATE_CONSUME;
+	}
+#else
+	/* Work around servers sending back CNAME with different delegation and no AA. */
+	if (an->count > 0 && ns->count > 0) {
+		const knot_rrset_t *rr = knot_pkt_rr(an, 0);
+		if (rr->type == KNOT_RRTYPE_CNAME) {
+			return KR_STATE_CONSUME;
+		}
+		/* Work around for these NSs which are authoritative both for
+		 * parent and child and mixes data from both zones in single answer */
+		if (knot_wire_get_aa(pkt->wire) &&
+		    (rr->type == qry->stype) &&
+		    (knot_dname_is_equal(rr->owner, qry->sname))) {
+			return KR_STATE_CONSUME;
+		}
+	}
+#endif
+	/* Remember current bailiwick for NS processing. */
+	const knot_dname_t *current_zone_cut = qry->zone_cut.name;
+	bool ns_record_exists = false;
+	int glue_cnt = 0;
+	/* Update zone cut information. */
+	for (unsigned i = 0; i < ns->count; ++i) {
+		const knot_rrset_t *rr = knot_pkt_rr(ns, i);
+		if (rr->type == KNOT_RRTYPE_NS) {
+			ns_record_exists = true;
+			int state = update_cut(pkt, rr, req, current_zone_cut, &glue_cnt);
+			switch(state) {
+			case KR_STATE_DONE: result = state; break;
+			case KR_STATE_FAIL: return state; break;
+			default:              /* continue */ break;
+			}
+		} else if (rr->type == KNOT_RRTYPE_SOA
+			   && knot_dname_in_bailiwick(rr->owner, qry->zone_cut.name) > 0) {
+			/* SOA below cut in authority indicates different authority,
+			 * but same NS set. */
+			qry->zone_cut.name = knot_dname_copy(rr->owner, &req->pool);
+		}
+	}
+
+	/* Nameserver is authoritative for both parent side and the child side of the
+	 * delegation may respond with an NS record in the answer section, and still update
+	 * the zone cut (e.g. what a.gtld-servers.net would respond for `com NS`) */
+	if (!ns_record_exists && knot_wire_get_aa(pkt->wire)) {
+		for (unsigned i = 0; i < an->count; ++i) {
+			const knot_rrset_t *rr = knot_pkt_rr(an, i);
+			if (rr->type == KNOT_RRTYPE_NS
+			    && knot_dname_in_bailiwick(rr->owner, qry->zone_cut.name) > 0) {
+				/* NS below cut in authority indicates different authority,
+				 * but same NS set. */
+				qry->zone_cut.name = knot_dname_copy(rr->owner, &req->pool);
+			}
+		}
+	}
+
+	if (glue_cnt) {
+		VERBOSE_MSG("<= loaded %d glue addresses\n", glue_cnt);
+	}
+
+
+	if ((qry->flags.DNSSEC_WANT) && (result == KR_STATE_CONSUME)) {
+		if (knot_wire_get_aa(pkt->wire) == 0 &&
+		    knot_wire_get_ancount(pkt->wire) == 0 &&
+		    ns_record_exists) {
+			/* Unhelpful referral
+			   Prevent from validating as an authoritative answer */
+			result = KR_STATE_DONE;
+		}
+	}
+
+	/* CONSUME => Unhelpful referral.
+	 * DONE    => Zone cut updated.  */
+	return result;
+}
+
+static int finalize_answer(knot_pkt_t *pkt, struct kr_request *req)
+{
+	/* Finalize header */
+	knot_pkt_t *answer = kr_request_ensure_answer(req);
+	if (answer) {
+		knot_wire_set_rcode(answer->wire, knot_wire_get_rcode(pkt->wire));
+		req->state = KR_STATE_DONE;
+	}
+	return req->state;
+}
+
+static int unroll_cname(knot_pkt_t *pkt, struct kr_request *req, bool referral, const knot_dname_t **cname_ret)
+{
+	struct kr_query *query = req->current_query;
+	assert(!(query->flags.STUB));
+	/* Process answer type */
+	const knot_pktsection_t *an = knot_pkt_section(pkt, KNOT_ANSWER);
+	const knot_dname_t *cname = NULL;
+	const knot_dname_t *pending_cname = query->sname;
+	bool is_final = (query->parent == NULL);
+	bool strict_mode = (query->flags.STRICT);
+
+	query->cname_depth = query->cname_parent ? query->cname_parent->cname_depth : 1;
+
+	do {
+		/* CNAME was found at previous iteration, but records may not follow the correct order.
+		 * Try to find records for pending_cname owner from section start. */
+		cname = pending_cname;
+		size_t cname_answ_selected_i = -1;
+		bool cname_is_occluded = false; /* whether `cname` is in a DNAME's bailiwick */
+		pending_cname = NULL;
+		const int cname_labels = knot_dname_labels(cname, NULL);
+		for (unsigned i = 0; i < an->count; ++i) {
+			const knot_rrset_t *rr = knot_pkt_rr(an, i);
+
+			/* Skip the RR if its owner+type doesn't interest us. */
+			const uint16_t type = kr_rrset_type_maysig(rr);
+			const bool type_OK = rr->type == query->stype || type == query->stype
+						|| type == KNOT_RRTYPE_CNAME;
+			if (rr->rclass != KNOT_CLASS_IN
+			    || knot_dname_in_bailiwick(rr->owner, query->zone_cut.name) < 0) {
+				continue;
+			}
+			const bool all_OK = type_OK && knot_dname_is_equal(rr->owner, cname);
+
+			const bool to_wire = is_final && !referral;
+
+			if (!all_OK && type == KNOT_RRTYPE_DNAME
+					&& knot_dname_in_bailiwick(cname, rr->owner) >= 1) {
+				/* This DNAME (or RRSIGs) cover the current target (`cname`),
+				 * so it is interesting and will occlude its CNAME.
+				 * We rely on CNAME being sent along with DNAME
+				 * (mandatory unless YXDOMAIN). */
+				cname_is_occluded = true;
+				uint8_t rank = get_initial_rank(rr, query, true,
+						query->flags.FORWARD || referral);
+				int ret = kr_ranked_rrarray_add(&req->answ_selected, rr,
+						rank, to_wire, query->uid, &req->pool);
+				if (ret < 0) {
+					return KR_STATE_FAIL;
+				}
+			}
+			if (!all_OK) {
+				continue;
+			}
+
+			if (rr->type == KNOT_RRTYPE_RRSIG) {
+				int rrsig_labels = knot_rrsig_labels(rr->rrs.rdata);
+				if (rrsig_labels > cname_labels) {
+					/* clearly wrong RRSIG, don't pick it.
+					 * don't fail immediately,
+					 * let validator work. */
+					continue;
+				}
+				if (rrsig_labels < cname_labels) {
+					query->flags.DNSSEC_WEXPAND = true;
+				}
+			}
+
+			/* Process records matching current SNAME */
+			if (!is_final) {
+				int cnt_ = 0;
+				int state = update_nsaddr(rr, query->parent, &cnt_);
+				if (state & KR_STATE_FAIL) {
+					return state;
+				}
+			}
+			uint8_t rank = get_initial_rank(rr, query, true,
+					query->flags.FORWARD || referral);
+			int ret = kr_ranked_rrarray_add(&req->answ_selected, rr,
+						rank, to_wire, query->uid, &req->pool);
+			if (ret < 0) {
+				return KR_STATE_FAIL;
+			}
+			cname_answ_selected_i = ret;
+
+			/* Select the next CNAME target, but don't jump immediately.
+			 * There can be records for "old" cname (RRSIGs are interesting);
+			 * more importantly there might be a DNAME for `cname_is_occluded`. */
+			if (query->stype != KNOT_RRTYPE_CNAME && rr->type == KNOT_RRTYPE_CNAME) {
+				pending_cname = knot_cname_name(rr->rrs.rdata);
+				if (!pending_cname) {
+					break;
+				}
+			}
+		}
+		if (!pending_cname) {
+			break;
+		}
+		if (cname_is_occluded) {
+			req->answ_selected.at[cname_answ_selected_i]->dont_cache = true;
+		}
+		if (++(query->cname_depth) > KR_CNAME_CHAIN_LIMIT) {
+			VERBOSE_MSG("<= error: CNAME chain exceeded max length %d\n",
+					/* people count objects from 0, no CNAME = 0 */
+					(int)KR_CNAME_CHAIN_LIMIT - 1);
+			return KR_STATE_FAIL;
+		}
+
+		if (knot_dname_is_equal(cname, pending_cname)) {
+			VERBOSE_MSG("<= error: CNAME chain loop detected\n");
+			return KR_STATE_FAIL;
+		}
+		/* In strict mode, explicitly fetch each CNAME target. */
+		if (strict_mode) {
+			cname = pending_cname;
+			break;
+		}
+		/* Information outside bailiwick is not trusted. */
+		if (knot_dname_in_bailiwick(pending_cname, query->zone_cut.name) < 0) {
+			cname = pending_cname;
+			break;
+		}
+		/* The validator still can't handle multiple zones in one answer,
+		 * so we only follow if a single label is replaced.
+		 * Forwarding appears to be even more sensitive to this.
+		 * TODO: iteration can probably handle the remaining cases,
+		 * but overall it would be better to have a smarter validator
+		 * (and thus save roundtrips).*/
+		const int pending_labels = knot_dname_labels(pending_cname, NULL);
+		if (pending_labels != cname_labels) {
+			cname = pending_cname;
+			break;
+		}
+		if (knot_dname_matched_labels(pending_cname, cname) != cname_labels - 1
+		    || query->flags.FORWARD) {
+			cname = pending_cname;
+			break;
+		}
+	} while (true);
+	*cname_ret = cname;
+	return kr_ok();
+}
+
+static int process_referral_answer(knot_pkt_t *pkt, struct kr_request *req)
+{
+	const knot_dname_t *cname = NULL;
+	int state = unroll_cname(pkt, req, true, &cname);
+	struct kr_query *query = req->current_query;
+	if (state != kr_ok()) {
+		query->server_selection.error(query, req->upstream.transport, KR_SELECTION_BAD_CNAME);
+		return KR_STATE_FAIL;
+	}
+	if (!(query->flags.CACHED)) {
+		/* If not cached (i.e. got from upstream)
+		 * make sure that this is not an authoritative answer
+		 * (even with AA=1) for other layers.
+		 * There can be answers with AA=1,
+		 * empty answer section and NS in authority.
+		 * Clearing of AA prevents them from
+		 * caching in the packet cache.
+		 * If packet already cached, don't touch him. */
+		knot_wire_clear_aa(pkt->wire);
+	}
+	state = pick_authority(pkt, req, false);
+	return state == kr_ok() ? KR_STATE_DONE : KR_STATE_FAIL;
+}
+
+static int process_final(knot_pkt_t *pkt, struct kr_request *req,
+			 const knot_dname_t *cname)
+{
+	const int pkt_class = kr_response_classify(pkt);
+	struct kr_query *query = req->current_query;
+	ranked_rr_array_t *array = &req->answ_selected;
+	for (size_t i = 0; i < array->len; ++i) {
+		const knot_rrset_t *rr = array->at[i]->rr;
+		if (!knot_dname_is_equal(rr->owner, cname)) {
+			continue;
+		}
+		if ((rr->rclass != query->sclass) ||
+		    (rr->type != query->stype)) {
+			continue;
+		}
+		const bool to_wire = ((pkt_class & (PKT_NXDOMAIN|PKT_NODATA)) != 0);
+		const int state = pick_authority(pkt, req, to_wire);
+		if (state != kr_ok()) {
+			return KR_STATE_FAIL;
+		}
+		if (!array->at[i]->to_wire) {
+			const size_t last_idx = array->len - 1;
+			size_t j = i;
+			ranked_rr_array_entry_t *entry = array->at[i];
+			/* Relocate record to the end, after current cname */
+			while (j < last_idx) {
+				array->at[j] = array->at[j + 1];
+				++j;
+			}
+			array->at[last_idx] = entry;
+			entry->to_wire = true;
+		}
+		return finalize_answer(pkt, req);
+	}
+	return kr_ok();
+}
+
+static int process_answer(knot_pkt_t *pkt, struct kr_request *req)
+{
+	struct kr_query *query = req->current_query;
+
+	/* Response for minimized QNAME.  Note that current iterator's minimization
+	 * is only able ask one label below a zone cut.
+	 * NODATA   => may be empty non-terminal, retry (found zone cut)
+	 * NOERROR  => found zone cut, retry, except the case described below
+	 * NXDOMAIN => parent is zone cut, retry as a workaround for bad authoritatives
+	 */
+	const bool is_final = (query->parent == NULL);
+	const int pkt_class = kr_response_classify(pkt);
+	const knot_dname_t * pkt_qname = knot_pkt_qname(pkt);
+	if (!knot_dname_is_equal(pkt_qname, query->sname) &&
+	    (pkt_class & (PKT_NOERROR|PKT_NXDOMAIN|PKT_REFUSED|PKT_NODATA))) {
+		/* Check for parent server that is authoritative for child zone,
+		 * several CCTLDs where the SLD and TLD have the same name servers */
+		const knot_pktsection_t *ans = knot_pkt_section(pkt, KNOT_ANSWER);
+		if ((pkt_class & (PKT_NOERROR)) && ans->count > 0 &&
+		     knot_dname_is_equal(pkt_qname, query->zone_cut.name)) {
+			VERBOSE_MSG("<= continuing with qname minimization\n");
+		} else {
+			/* fall back to disabling minimization */
+			VERBOSE_MSG("<= retrying with non-minimized name\n");
+			query->flags.NO_MINIMIZE = true;
+		}
+		return KR_STATE_CONSUME;
+	}
+
+	/* This answer didn't improve resolution chain, therefore must be authoritative (relaxed to negative). */
+	if (!is_authoritative(pkt, query)) {
+		if (!(query->flags.FORWARD) &&
+		    pkt_class & (PKT_NXDOMAIN|PKT_NODATA)) {
+			query->server_selection.error(query, req->upstream.transport, KR_SELECTION_LAME_DELEGATION);
+			VERBOSE_MSG("<= lame response: non-auth sent negative response\n");
+			return KR_STATE_FAIL;
+		}
+	}
+
+	const knot_dname_t *cname = NULL;
+	/* Process answer type */
+	int state = unroll_cname(pkt, req, false, &cname);
+	if (state != kr_ok()) {
+		query->server_selection.error(query, req->upstream.transport, KR_SELECTION_BAD_CNAME);
+		return state;
+	}
+	/* Make sure that this is an authoritative answer (even with AA=0) for other layers */
+	knot_wire_set_aa(pkt->wire);
+	/* Either way it resolves current query. */
+	query->flags.RESOLVED = true;
+	/* Follow canonical name as next SNAME. */
+	if (!knot_dname_is_equal(cname, query->sname)) {
+		/* Check if target record has been already copied */
+		query->flags.CNAME = true;
+		if (is_final) {
+			state = process_final(pkt, req, cname);
+			if (state != kr_ok()) {
+				return state;
+			}
+		} else if ((query->flags.FORWARD) &&
+			   ((query->stype == KNOT_RRTYPE_DS) ||
+			    (query->stype == KNOT_RRTYPE_NS))) {
+			/* CNAME'ed answer for DS or NS subquery.
+			 * Treat it as proof of zonecut nonexistance. */
+			return KR_STATE_DONE;
+		}
+		VERBOSE_MSG("<= cname chain, following\n");
+		/* Check if the same query was followed in the same CNAME chain. */
+		for (const struct kr_query *q = query->cname_parent; q != NULL;
+				q = q->cname_parent) {
+			if (q->sclass == query->sclass &&
+			    q->stype == query->stype   &&
+			    knot_dname_is_equal(q->sname, cname)) {
+				VERBOSE_MSG("<= cname chain loop\n");
+				query->server_selection.error(query, req->upstream.transport, KR_SELECTION_BAD_CNAME);
+				return KR_STATE_FAIL;
+			}
+		}
+		struct kr_query *next = kr_rplan_push(&req->rplan, query->parent, cname, query->sclass, query->stype);
+		if (!next) {
+			return KR_STATE_FAIL;
+		}
+		next->flags.AWAIT_CUT = true;
+
+		/* Copy transitive flags from original query to CNAME followup. */
+		next->flags.TRACE = query->flags.TRACE;
+		next->flags.ALWAYS_CUT = query->flags.ALWAYS_CUT;
+
+		/* Original query might have turned minimization off, revert. */
+		next->flags.NO_MINIMIZE = req->options.NO_MINIMIZE;
+
+		if (query->flags.FORWARD) {
+			next->forward_flags.CNAME = true;
+		}
+		next->cname_parent = query;
+		/* Want DNSSEC if and only if it's posible to secure
+		 * this name (i.e. iff it is covered by a TA) */
+		if (kr_ta_covers_qry(req->ctx, cname, query->stype)) {
+			next->flags.DNSSEC_WANT = true;
+		} else {
+			next->flags.DNSSEC_WANT = false;
+		}
+		if (!(query->flags.FORWARD) ||
+		    (query->flags.DNSSEC_WEXPAND)) {
+			state = pick_authority(pkt, req, false);
+			if (state != kr_ok()) {
+				return KR_STATE_FAIL;
+			}
+		}
+	} else if (!query->parent) {
+		/* Answer for initial query */
+		const bool to_wire = ((pkt_class & (PKT_NXDOMAIN|PKT_NODATA)) != 0);
+		state = pick_authority(pkt, req, to_wire);
+		if (state != kr_ok()) {
+			return KR_STATE_FAIL;
+		}
+		return finalize_answer(pkt, req);
+	} else {
+		/* Answer for sub-query; DS, IP for NS etc.
+		 * It may contains NSEC \ NSEC3 records for
+		 * data non-existence or wc expansion proving.
+		 * If yes, they must be validated by validator.
+		 * If no, authority section is unuseful.
+		 * dnssec\nsec.c & dnssec\nsec3.c use
+		 * rrsets from incoming packet.
+		 * validator uses answer_selected & auth_selected.
+		 * So, if nsec\nsec3 records are present in authority,
+		 * pick_authority() must be called.
+		 * TODO refactor nsec\nsec3 modules to work with
+		 * answer_selected & auth_selected instead of incoming pkt. */
+		bool auth_is_unuseful = true;
+		const knot_pktsection_t *ns = knot_pkt_section(pkt, KNOT_AUTHORITY);
+		for (unsigned i = 0; i < ns->count; ++i) {
+			const knot_rrset_t *rr = knot_pkt_rr(ns, i);
+			if (rr->type == KNOT_RRTYPE_NSEC ||
+			    rr->type == KNOT_RRTYPE_NSEC3) {
+				auth_is_unuseful = false;
+				break;
+			}
+		}
+		if (!auth_is_unuseful) {
+			state = pick_authority(pkt, req, false);
+			if (state != kr_ok()) {
+				return KR_STATE_FAIL;
+			}
+		}
+	}
+	return KR_STATE_DONE;
+}
+
+/** @internal like process_answer() but for the STUB mode. */
+static int process_stub(knot_pkt_t *pkt, struct kr_request *req)
+{
+	struct kr_query *query = req->current_query;
+	assert(query->flags.STUB);
+	/* Pick all answer RRs. */
+	const knot_pktsection_t *an = knot_pkt_section(pkt, KNOT_ANSWER);
+	for (unsigned i = 0; i < an->count; ++i) {
+		const knot_rrset_t *rr = knot_pkt_rr(an, i);
+		int err = kr_ranked_rrarray_add(&req->answ_selected, rr,
+			      KR_RANK_OMIT | KR_RANK_AUTH, true, query->uid, &req->pool);
+		/* KR_RANK_AUTH: we don't have the records directly from
+		 * an authoritative source, but we do trust the server and it's
+		 * supposed to only send us authoritative records. */
+		if (err < 0) {
+			return KR_STATE_FAIL;
+		}
+	}
+
+	knot_wire_set_aa(pkt->wire);
+	query->flags.RESOLVED = true;
+	/* Pick authority RRs. */
+	int pkt_class = kr_response_classify(pkt);
+	const bool to_wire = ((pkt_class & (PKT_NXDOMAIN|PKT_NODATA)) != 0);
+	int err = pick_authority(pkt, req, to_wire);
+	if (err != kr_ok()) {
+		return KR_STATE_FAIL;
+	}
+
+	return finalize_answer(pkt, req);
+}
+
+/* State-less single resolution iteration step, not needed. */
+static int reset(kr_layer_t *ctx)  { return KR_STATE_PRODUCE; }
+
+/* Set resolution context and parameters. */
+static int begin(kr_layer_t *ctx)
+{
+	if (ctx->state & (KR_STATE_DONE|KR_STATE_FAIL)) {
+		return ctx->state;
+	}
+	/*
+	 * RFC7873 5.4 extends the QUERY operation code behaviour in order to
+	 * be able to generate requests for server cookies. Such requests have
+	 * QDCOUNT equal to zero and must contain a cookie option.
+	 * Server cookie queries must be handled by the cookie module/layer
+	 * before this layer.
+	 */
+	const knot_pkt_t *pkt = ctx->req->qsource.packet;
+	if (!pkt || knot_wire_get_qdcount(pkt->wire) == 0) {
+		return KR_STATE_FAIL;
+	}
+
+	struct kr_query *qry = ctx->req->current_query;
+	/* Avoid any other classes, and avoid any meta-types ~~except for ANY~~. */
+	if (qry->sclass != KNOT_CLASS_IN
+	    || (knot_rrtype_is_metatype(qry->stype)
+		    /* && qry->stype != KNOT_RRTYPE_ANY hmm ANY seems broken ATM */)) {
+		knot_pkt_t *ans = kr_request_ensure_answer(ctx->req);
+		if (!ans) return ctx->req->state;
+		knot_wire_set_rcode(ans->wire, KNOT_RCODE_NOTIMPL);
+		return KR_STATE_FAIL;
+	}
+
+	return reset(ctx);
+}
+
+int kr_make_query(struct kr_query *query, knot_pkt_t *pkt)
+{
+	/* Minimize QNAME (if possible). */
+	uint16_t qtype = query->stype;
+	const knot_dname_t *qname = minimized_qname(query, &qtype);
+
+	/* Form a query for the authoritative. */
+	knot_pkt_clear(pkt);
+	int ret = knot_pkt_put_question(pkt, qname, query->sclass, qtype);
+	if (ret != KNOT_EOK) {
+		return ret;
+	}
+
+	/* Query built, expect answer. */
+	query->id = kr_rand_bytes(2);
+	/* We must respect https://tools.ietf.org/html/rfc7766#section-6.2.1
+	 * -  When sending multiple queries over a TCP connection, clients MUST NOT
+	 *    reuse the DNS Message ID of an in-flight query on that connection.
+	 *
+	 * So, if query is going to be sent over TCP connection
+	 * this id can be changed to avoid duplication with query that already was sent
+	 * but didn't receive answer yet.
+	 */
+	knot_wire_set_id(pkt->wire, query->id);
+	pkt->parsed = pkt->size;
+
+	return kr_ok();
+}
+
+static int prepare_query(kr_layer_t *ctx, knot_pkt_t *pkt)
+{
+	assert(pkt && ctx);
+	struct kr_request *req = ctx->req;
+	struct kr_query *query = req->current_query;
+	if (!query || ctx->state & (KR_STATE_DONE|KR_STATE_FAIL)) {
+		return ctx->state;
+	}
+
+	/* Make query */
+	int ret = kr_make_query(query, pkt);
+	if (ret != 0) {
+		return KR_STATE_FAIL;
+	}
+
+	WITH_VERBOSE(query) {
+		KR_DNAME_GET_STR(name_str, query->sname);
+		KR_RRTYPE_GET_STR(type_str, query->stype);
+		QVERBOSE_MSG(query, "'%s' type '%s' new uid was assigned .%02u, parent uid .%02u\n",
+			    name_str, type_str, req->rplan.next_uid,
+			    query->parent ? query->parent->uid : 0);
+	}
+
+	query->uid = req->rplan.next_uid;
+	req->rplan.next_uid += 1;
+
+	return KR_STATE_CONSUME;
+}
+
+static bool satisfied_by_additional(const struct kr_query *qry)
+{
+	const bool prereq = !qry->flags.STUB && !qry->flags.FORWARD && qry->flags.NONAUTH;
+	if (!prereq)
+		return false;
+	const struct kr_request *req = qry->request;
+	for (ssize_t i = req->add_selected.len - 1; i >= 0; --i) {
+		ranked_rr_array_entry_t *entry = req->add_selected.at[i];
+		if (entry->qry_uid != qry->uid)
+			break;
+		if (entry->rr->type == qry->stype
+		    && knot_dname_is_equal(entry->rr->owner, qry->sname)) {
+			return true;
+		}
+	}
+	return false;
+}
+
+/** Resolve input query or continue resolution with followups.
+ *
+ *  This roughly corresponds to RFC1034, 5.3.3 4a-d.
+ */
+static int resolve(kr_layer_t *ctx, knot_pkt_t *pkt)
+{
+	assert(pkt && ctx);
+	struct kr_request *req = ctx->req;
+	struct kr_query *query = req->current_query;
+	if (!query) {
+		return ctx->state;
+	}
+	query->flags.PKT_IS_SANE = false;
+
+	WITH_VERBOSE(query) {
+		if (query->flags.TRACE) {
+			auto_free char *pkt_text = kr_pkt_text(pkt);
+			VERBOSE_MSG("<= answer received: \n%s\n", pkt_text);
+		}
+	}
+
+	if (query->flags.RESOLVED || query->flags.BADCOOKIE_AGAIN) {
+		return ctx->state;
+	}
+
+	/* Check for packet processing errors first.
+	 * Note - we *MUST* check if it has at least a QUESTION,
+	 * otherwise it would crash on accessing QNAME. */
+#ifdef STRICT_MODE
+	if (pkt->parsed < pkt->size) {
+		VERBOSE_MSG("<= pkt contains excessive data\n");
+		return KR_STATE_FAIL;
+	} else
+#endif
+	if (pkt->parsed <= KNOT_WIRE_HEADER_SIZE) {
+		if (pkt->parsed == KNOT_WIRE_HEADER_SIZE && knot_wire_get_rcode(pkt->wire) == KNOT_RCODE_FORMERR) {
+			/* This is a special case where we get valid header with FORMERR and nothing else.
+			 * This happens on some authoritatives which don't support EDNS and don't
+			 * bother copying the SECTION QUESTION. */
+			query->server_selection.error(query, req->upstream.transport, KR_SELECTION_FORMERR);
+			return KR_STATE_FAIL;
+		}
+		VERBOSE_MSG("<= malformed response (parsed %d)\n", (int)pkt->parsed);
+		query->server_selection.error(query, req->upstream.transport, KR_SELECTION_MALFORMED);
+		return KR_STATE_FAIL;
+	} else if (!is_paired_to_query(pkt, query)) {
+		WITH_VERBOSE(query) {
+			const char *ns_str =
+				req->upstream.transport ? kr_straddr(&req->upstream.transport->address.ip) : "(internal)";
+			VERBOSE_MSG("<= ignoring mismatching response from %s\n",
+					ns_str ? ns_str : "(kr_straddr failed)");
+		}
+		query->server_selection.error(query, req->upstream.transport, KR_SELECTION_MISMATCHED);
+		return KR_STATE_FAIL;
+	} else if (knot_wire_get_tc(pkt->wire)) {
+		VERBOSE_MSG("<= truncated response, failover to TCP\n");
+		if (query) {
+			/* Fail if already on TCP. */
+			if (req->upstream.transport->protocol != KR_TRANSPORT_UDP) {
+				VERBOSE_MSG("<= TC=1 with TCP, bailing out\n");
+				query->server_selection.error(query, req->upstream.transport, KR_SELECTION_TRUNCATED);
+				return KR_STATE_FAIL;
+			}
+			query->server_selection.error(query, req->upstream.transport, KR_SELECTION_TRUNCATED);
+		}
+		return KR_STATE_CONSUME;
+	}
+
+	/* If exiting above here, there's no sense to put it into packet cache.
+	 * The most important part is to check for spoofing: is_paired_to_query() */
+	query->flags.PKT_IS_SANE = true;
+
+#ifndef NOVERBOSELOG
+	const knot_lookup_t *rcode = knot_lookup_by_id(knot_rcode_names, knot_wire_get_rcode(pkt->wire));
+#endif
+
+	// We can't return directly from the switch because we have to give feedback to server selection first
+	int ret = 0;
+	int selection_error = KR_SELECTION_OK;
+
+	/* Check response code. */
+	switch(knot_wire_get_rcode(pkt->wire)) {
+	case KNOT_RCODE_NOERROR:
+	case KNOT_RCODE_NXDOMAIN:
+		break; /* OK */
+	case KNOT_RCODE_YXDOMAIN: /* Basically a successful answer; name just doesn't fit. */
+		if (!kr_request_ensure_answer(req)) {
+			ret = req->state;
+		}
+		knot_wire_set_rcode(req->answer->wire, KNOT_RCODE_YXDOMAIN);
+		break;
+	case KNOT_RCODE_REFUSED:
+		if (query->flags.STUB) {
+			 /* just pass answer through if in stub mode */
+			break;
+		}
+		ret = KR_STATE_FAIL;
+		selection_error = KR_SELECTION_REFUSED;
+		break;
+	case KNOT_RCODE_SERVFAIL:
+		if (query->flags.STUB) {
+			 /* just pass answer through if in stub mode */
+			break;
+		}
+		ret = KR_STATE_FAIL;
+		selection_error = KR_SELECTION_SERVFAIL;
+		break;
+	case KNOT_RCODE_FORMERR:
+		ret = KR_STATE_FAIL;
+		if (knot_pkt_has_edns(pkt)) {
+			selection_error = KR_SELECTION_FORMERR_EDNS;
+		} else {
+			selection_error = KR_SELECTION_FORMERR;
+		}
+		break;
+	case KNOT_RCODE_NOTIMPL:
+		ret = KR_STATE_FAIL;
+		selection_error = KR_SELECTION_NOTIMPL;
+		break;
+	default:
+		ret = KR_STATE_FAIL;
+		selection_error = KR_SELECTION_OTHER_RCODE;
+		break;
+	}
+
+	if (query->server_selection.initialized) {
+		query->server_selection.error(query, req->upstream.transport, selection_error);
+	}
+
+	if (ret) {
+		VERBOSE_MSG("<= rcode: %s\n", rcode ? rcode->name : "??");
+		return ret;
+	}
+
+	int state;
+	/* Forwarding/stub mode is special. */
+	if (query->flags.STUB) {
+		state = process_stub(pkt, req);
+		goto rrarray_finalize;
+	}
+
+	/* Resolve authority to see if it's referral or authoritative. */
+	state = process_authority(pkt, req);
+	switch(state) {
+	case KR_STATE_CONSUME: /* Not referral, process answer. */
+		VERBOSE_MSG("<= rcode: %s\n", rcode ? rcode->name : "??");
+		state = process_answer(pkt, req);
+		break;
+	case KR_STATE_DONE: /* Referral */
+		state = process_referral_answer(pkt,req);
+		if (satisfied_by_additional(query)) { /* This is a little hacky.
+			 * We found sufficient information in ADDITIONAL section
+			 * and it was selected for caching in this CONSUME round.
+			 * To make iterator accept the record in a simple way,
+			 * we trigger another cache *reading* attempt
+			 * for the subsequent PRODUCE round.
+			 */
+			assert(query->flags.NONAUTH);
+			query->flags.CACHE_TRIED = false;
+			VERBOSE_MSG("<= referral response, but cache should stop us short now\n");
+		} else {
+			VERBOSE_MSG("<= referral response, follow\n");
+		}
+		break;
+	default:
+		break;
+	}
+
+rrarray_finalize:
+	/* Finish construction of libknot-format RRsets.
+	 * We do this even if dropping the answer, though it's probably useless. */
+	(void)0;
+	ranked_rr_array_t *selected[] = kr_request_selected(req);
+	for (knot_section_t i = KNOT_ANSWER; i <= KNOT_ADDITIONAL; ++i) {
+		ret = kr_ranked_rrarray_finalize(selected[i], query->uid, &req->pool);
+		if (unlikely(ret)) {
+			return KR_STATE_FAIL;
+		}
+	}
+
+	return state;
+}
+
+/** Module implementation. */
+int iterate_init(struct kr_module *self)
+{
+	static const kr_layer_api_t layer = {
+		.begin = &begin,
+		.reset = &reset,
+		.consume = &resolve,
+		.produce = &prepare_query
+	};
+	self->layer = &layer;
+	return kr_ok();
+}
+
+KR_MODULE_EXPORT(iterate) /* useless for builtin module, but let's be consistent */
+
+#undef VERBOSE_MSG
diff --git a/lib/layer/iterate.h b/lib/layer/iterate.h
new file mode 100644
index 0000000..e5ebe38
--- /dev/null
+++ b/lib/layer/iterate.h
@@ -0,0 +1,25 @@
+/*  Copyright (C) 2014-2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#pragma once
+
+#include "lib/layer.h"
+#include "lib/rplan.h"
+
+/* Packet classification. */
+enum {
+	PKT_NOERROR   = 1 << 0, /* Positive response */
+	PKT_NODATA    = 1 << 1, /* No data response */
+	PKT_NXDOMAIN  = 1 << 2, /* Negative response */
+	PKT_REFUSED   = 1 << 3, /* Refused response */
+	PKT_ERROR     = 1 << 4  /* Bad message */
+};
+
+/** Classify response by type. */
+KR_EXPORT
+int kr_response_classify(const knot_pkt_t *pkt);
+
+/** Make next iterative query. */
+KR_EXPORT
+int kr_make_query(struct kr_query *query, knot_pkt_t *pkt);
diff --git a/lib/layer/mode.rst b/lib/layer/mode.rst
new file mode 100644
index 0000000..d64257e
--- /dev/null
+++ b/lib/layer/mode.rst
@@ -0,0 +1,26 @@
+.. SPDX-License-Identifier: GPL-3.0-or-later
+
+.. function:: mode(['strict' | 'normal' | 'permissive'])
+
+   :param: New checking level specified as string (*optional*).
+   :return: Current checking level.
+
+   Get or change resolver strictness checking level.
+
+   By default, resolver runs in *normal* mode. There are possibly many small adjustments
+   hidden behind the mode settings, but the main idea is that in *permissive* mode, the resolver
+   tries to resolve a name with as few lookups as possible, while in *strict* mode it spends much
+   more effort resolving and checking referral path. However, if majority of the traffic is covered
+   by DNSSEC, some of the strict checking actions are counter-productive.
+
+   .. csv-table::
+    :header: "Glue type", "Modes when it is accepted",   "Example glue [#example_glue]_"
+
+    "mandatory glue",     "strict, normal, permissive",  "ns1.example.org"
+    "in-bailiwick glue",  "normal, permissive",          "ns1.example2.org"
+    "any glue records",   "permissive",                  "ns1.example3.net"
+
+   .. [#example_glue] The examples show glue records acceptable from servers
+        authoritative for `org` zone when delegating to `example.org` zone.
+        Unacceptable or missing glue records trigger resolution of names listed
+        in NS records before following respective delegation.
diff --git a/lib/layer/test.integr/deckard.yaml b/lib/layer/test.integr/deckard.yaml
new file mode 100644
index 0000000..d2d62d0
--- /dev/null
+++ b/lib/layer/test.integr/deckard.yaml
@@ -0,0 +1,13 @@
+# SPDX-License-Identifier: GPL-3.0-or-later
+programs:
+- name: kresd
+  binary: kresd
+  additional:
+    - --noninteractive
+  templates:
+    - lib/layer/test.integr/kresd_config.j2
+    - tests/integration/hints_zone.j2
+  configs:
+    - config
+    - hints
+noclean: True
diff --git a/lib/layer/test.integr/iter_cname_length.rpl b/lib/layer/test.integr/iter_cname_length.rpl
new file mode 100644
index 0000000..39f48a8
--- /dev/null
+++ b/lib/layer/test.integr/iter_cname_length.rpl
@@ -0,0 +1,226 @@
+do-ip6: no
+; config options
+; SPDX-License-Identifier: GPL-3.0-or-later
+	stub-addr: 193.0.14.129 	# k.root-servers.net.
+CONFIG_END
+
+SCENARIO_BEGIN Test restriction on CNAME chain length.
+
+
+; k.root-servers.net.
+RANGE_BEGIN 0 100
+	ADDRESS 193.0.14.129
+
+ENTRY_BEGIN
+MATCH opcode qname
+ADJUST copy_id copy_query
+REPLY QR NOERROR
+SECTION QUESTION
+n1.tld.	IN NS
+SECTION ANSWER
+n1.tld.	IN CNAME	n2.tld.
+n2.tld.	IN CNAME	n3.tld.
+n3.tld.	IN CNAME	n4.tld.
+n4.tld.	IN CNAME	n5.tld.
+n5.tld.	IN CNAME	n6.tld.
+n6.tld.	IN CNAME	n7.sub.
+SECTION AUTHORITY
+sub.		IN NS		ns.sub.
+SECTION ADDITIONAL
+ns.sub.		IN A		194.0.14.1
+ENTRY_END
+
+ENTRY_BEGIN
+MATCH opcode qname
+ADJUST copy_id copy_query
+REPLY QR NOERROR
+SECTION QUESTION
+n2.tld.	IN NS
+SECTION ANSWER
+n2.tld.	IN CNAME	n3.tld.
+n3.tld.	IN CNAME	n4.tld.
+n4.tld.	IN CNAME	n5.tld.
+n5.tld.	IN CNAME	n6.tld.
+n6.tld.	IN CNAME	n7.sub.
+SECTION AUTHORITY
+sub.		IN NS		ns.sub.
+SECTION ADDITIONAL
+ns.sub.		IN A		194.0.14.1
+ENTRY_END
+
+
+; empty non-terminal for query name minimization
+ENTRY_BEGIN
+MATCH opcode subdomain
+ADJUST copy_id copy_query
+REPLY QR AA NOERROR
+SECTION QUESTION
+tld.	IN NS
+SECTION ANSWER
+ENTRY_END
+
+
+
+; sub. subdomains
+ENTRY_BEGIN
+MATCH opcode subdomain
+ADJUST copy_id copy_query
+REPLY QR NOERROR
+SECTION QUESTION
+sub.		IN NS
+SECTION AUTHORITY
+sub.		IN NS		ns.sub.
+SECTION ADDITIONAL
+ns.sub.		IN A		194.0.14.1
+ENTRY_END
+
+RANGE_END
+
+
+; ns.sub.
+RANGE_BEGIN 0 100
+	ADDRESS 194.0.14.1
+
+ENTRY_BEGIN
+MATCH opcode qname qtype
+ADJUST copy_id
+REPLY QR AA NOERROR
+SECTION QUESTION
+ns.sub.		IN A
+SECTION ANSWER
+ns.sub.		IN A		194.0.14.1
+ENTRY_END
+
+ENTRY_BEGIN
+MATCH opcode qname qtype
+ADJUST copy_id
+REPLY QR AA NOERROR
+SECTION QUESTION
+ns.sub.		IN AAAA
+SECTION ANSWER
+ENTRY_END
+
+ENTRY_BEGIN
+MATCH opcode qname qtype
+ADJUST copy_id
+REPLY QR AA NOERROR
+SECTION QUESTION
+n7.sub.		IN A
+SECTION ANSWER
+n7.sub.	IN CNAME	n8.sub.
+n8.sub.	IN CNAME	n9.sub.
+n9.sub.	IN CNAME	n10.sub.
+n10.sub.	IN CNAME	n11.sub.
+n11.sub.	IN CNAME	n12.sub.
+n12.sub.	IN CNAME	n13.sub.
+n13.sub.	IN CNAME	n14.sub.
+n14.sub.	IN A		198.18.0.1
+ENTRY_END
+
+ENTRY_BEGIN
+MATCH opcode qname qtype
+ADJUST copy_id
+REPLY QR AA NOERROR
+SECTION QUESTION
+loop7.sub.		IN A
+SECTION ANSWER
+loop7.sub.	IN CNAME	loop8.sub.
+loop8.sub.	IN CNAME	loop9.sub.
+loop9.sub.	IN CNAME	loop10.sub.
+loop10.sub.	IN CNAME	loop11.sub.
+; loop11 -> loop7 -> ... -> loop11
+loop11.sub.	IN CNAME	loop7.sub.
+loop12.sub.	IN CNAME	loop13.sub.
+loop13.sub.	IN CNAME	loop14.sub.
+loop14.sub.	IN A		198.18.0.1
+ENTRY_END
+
+RANGE_END
+
+; maximum allowed chain length
+STEP 10 QUERY
+ENTRY_BEGIN
+REPLY RD
+SECTION QUESTION
+n2.tld.	IN A
+ENTRY_END
+
+STEP 11 CHECK_ANSWER
+ENTRY_BEGIN
+MATCH all
+REPLY QR RD RA NOERROR
+SECTION QUESTION
+n2.tld.	IN A
+SECTION ANSWER
+n2.tld.	IN CNAME	n3.tld.
+n3.tld.	IN CNAME	n4.tld.
+n4.tld.	IN CNAME	n5.tld.
+n5.tld.	IN CNAME	n6.tld.
+n6.tld.	IN CNAME	n7.sub.
+n7.sub.	IN CNAME	n8.sub.
+n8.sub.	IN CNAME	n9.sub.
+n9.sub.	IN CNAME	n10.sub.
+n10.sub.	IN CNAME	n11.sub.
+n11.sub.	IN CNAME	n12.sub.
+n12.sub.	IN CNAME	n13.sub.
+n13.sub.	IN CNAME	n14.sub.
+n14.sub.	IN A		198.18.0.1
+ENTRY_END
+
+
+; too long CNAME chain across two zones
+STEP 20 QUERY
+ENTRY_BEGIN
+REPLY RD
+SECTION QUESTION
+n1.tld.	IN A
+ENTRY_END
+
+STEP 21 CHECK_ANSWER
+ENTRY_BEGIN
+MATCH all
+REPLY QR RD RA SERVFAIL
+SECTION QUESTION
+n1.tld.	IN A
+SECTION ANSWER
+n1.tld.	IN CNAME	n2.tld.
+n2.tld.	IN CNAME	n3.tld.
+n3.tld.	IN CNAME	n4.tld.
+n4.tld.	IN CNAME	n5.tld.
+n5.tld.	IN CNAME	n6.tld.
+n6.tld.	IN CNAME	n7.sub.
+n7.sub.	IN CNAME	n8.sub.
+n8.sub.	IN CNAME	n9.sub.
+n9.sub.	IN CNAME	n10.sub.
+n10.sub.	IN CNAME	n11.sub.
+n11.sub.	IN CNAME	n12.sub.
+n12.sub.	IN CNAME	n13.sub.
+n13.sub.	IN CNAME	n14.sub.
+; This chain is too long (> 13):
+; n14.sub.	IN A		198.18.0.1
+ENTRY_END
+
+
+; CNAME loop detection
+STEP 30 QUERY
+ENTRY_BEGIN
+REPLY RD
+SECTION QUESTION
+loop7.sub.	IN A
+ENTRY_END
+
+STEP 31 CHECK_ANSWER
+ENTRY_BEGIN
+MATCH all
+REPLY QR RD RA SERVFAIL
+SECTION QUESTION
+loop7.sub.	IN A
+SECTION ANSWER
+loop7.sub.	IN CNAME	loop8.sub.
+loop8.sub.	IN CNAME	loop9.sub.
+loop9.sub.	IN CNAME	loop10.sub.
+loop10.sub.	IN CNAME	loop11.sub.
+loop11.sub.	IN CNAME	loop7.sub.
+ENTRY_END
+
+SCENARIO_END
diff --git a/lib/layer/test.integr/iter_limit_bad_glueless.rpl b/lib/layer/test.integr/iter_limit_bad_glueless.rpl
new file mode 100644
index 0000000..73d4627
--- /dev/null
+++ b/lib/layer/test.integr/iter_limit_bad_glueless.rpl
@@ -0,0 +1,220 @@
+do-ip6: no
+; config options
+;	target-fetch-policy: "0 0 0 0 0"
+;	name: "."
+	stub-addr: 193.0.14.129 	# K.ROOT-SERVERS.NET.
+CONFIG_END
+
+SCENARIO_BEGIN Test resolution with lame reply looks like nodata with noSOA
+
+; K.ROOT-SERVERS.NET.
+RANGE_BEGIN 0 100
+	ADDRESS 193.0.14.129
+ENTRY_BEGIN
+MATCH opcode qtype qname
+ADJUST copy_id
+REPLY QR NOERROR
+SECTION QUESTION
+. IN NS
+SECTION ANSWER
+. IN NS	K.ROOT-SERVERS.NET.
+SECTION ADDITIONAL
+K.ROOT-SERVERS.NET.	IN	A	193.0.14.129
+ENTRY_END
+
+; com
+ENTRY_BEGIN
+MATCH opcode subdomain
+ADJUST copy_id copy_query
+REPLY QR NOERROR
+SECTION QUESTION
+com. IN NS
+SECTION AUTHORITY
+com.	IN NS	a.gtld-servers.net.
+SECTION ADDITIONAL
+a.gtld-servers.net.	IN 	A	192.5.6.30
+ENTRY_END
+
+; net
+ENTRY_BEGIN
+MATCH opcode subdomain
+ADJUST copy_id copy_query
+REPLY QR NOERROR
+SECTION QUESTION
+net. IN NS
+SECTION AUTHORITY
+net.	IN NS	e.gtld-servers.net.
+SECTION ADDITIONAL
+e.gtld-servers.net.	IN 	A	192.12.94.30
+ENTRY_END
+
+RANGE_END
+
+; a.gtld-servers.net. - com
+RANGE_BEGIN 0 100
+	ADDRESS 192.5.6.30
+ENTRY_BEGIN
+MATCH opcode qtype qname
+ADJUST copy_id
+REPLY QR NOERROR
+SECTION QUESTION
+com. IN NS
+SECTION ANSWER
+com.	IN NS	a.gtld-servers.net.
+SECTION ADDITIONAL
+a.gtld-servers.net.	IN 	A	192.5.6.30
+ENTRY_END
+
+ENTRY_BEGIN
+MATCH opcode subdomain
+ADJUST copy_id copy_query
+REPLY QR NOERROR
+SECTION QUESTION
+victim.com. IN NS
+SECTION AUTHORITY
+victim.com.	IN NS	ns.victim.com.
+SECTION ADDITIONAL
+ns.victim.com.	IN A	1.2.3.55
+ENTRY_END
+RANGE_END
+
+; e.gtld-servers.net. - net
+RANGE_BEGIN 0 100
+	ADDRESS 192.12.94.30
+ENTRY_BEGIN
+MATCH opcode qtype qname
+ADJUST copy_id
+REPLY QR NOERROR
+SECTION QUESTION
+net. IN NS
+SECTION ANSWER
+net.	IN NS	e.gtld-servers.net.
+SECTION ADDITIONAL
+e.gtld-servers.net.	IN 	A	192.12.94.30
+ENTRY_END
+
+ENTRY_BEGIN
+MATCH opcode subdomain
+ADJUST copy_id copy_query
+REPLY QR NOERROR
+SECTION QUESTION
+attacker.net. IN NS
+SECTION AUTHORITY
+attacker.net.	IN NS	ns.attacker.net.
+SECTION ADDITIONAL
+ns.attacker.net.		IN 	A	1.2.3.44
+ENTRY_END
+RANGE_END
+
+; ns.attacker.net.
+RANGE_BEGIN 0 100
+	ADDRESS 1.2.3.44
+ENTRY_BEGIN
+MATCH opcode qtype qname
+ADJUST copy_id
+REPLY QR NOERROR
+SECTION QUESTION
+attacker.net. IN NS
+SECTION ANSWER
+attacker.net.	IN NS	ns.attacker.net.
+SECTION ADDITIONAL
+ns.attacker.net.		IN 	A	1.2.3.44
+ENTRY_END
+
+ENTRY_BEGIN
+MATCH opcode qtype qname
+ADJUST copy_id
+REPLY QR NOERROR
+SECTION QUESTION
+ns.attacker.net. IN A
+SECTION ANSWER
+ns.attacker.net. IN A	1.2.3.44
+SECTION AUTHORITY
+attacker.net.	IN NS	ns.attacker.net.
+ENTRY_END
+
+ENTRY_BEGIN
+MATCH opcode qtype qname
+ADJUST copy_id
+REPLY QR NOERROR
+SECTION QUESTION
+ns.attacker.net. IN AAAA
+SECTION AUTHORITY
+SECTION ADDITIONAL
+ENTRY_END
+
+ENTRY_BEGIN
+MATCH opcode subdomain
+ADJUST copy_id copy_query
+REPLY QR NOERROR
+SECTION QUESTION
+sub.attacker.net. IN NS
+SECTION AUTHORITY
+sub.attacker.net. IN NS	ns1.victim.com.
+sub.attacker.net. IN NS	ns2.victim.com.
+sub.attacker.net. IN NS	ns3.victim.com.
+sub.attacker.net. IN NS	ns4.victim.com.
+sub.attacker.net. IN NS	ns5.victim.com.
+sub.attacker.net. IN NS	ns6.victim.com.
+sub.attacker.net. IN NS	ns7.victim.com.
+sub.attacker.net. IN NS	ns8.victim.com.
+sub.attacker.net. IN NS	ns9.victim.com.
+ENTRY_END
+RANGE_END
+
+; ns.victim.com.
+; returns NXDOMAIN for all queries (attacker generated NS names are not present)
+RANGE_BEGIN 0 100
+	ADDRESS 1.2.3.55
+ENTRY_BEGIN
+MATCH opcode subdomain
+ADJUST copy_id copy_query
+REPLY QR NXDOMAIN
+SECTION QUESTION
+victim.com. IN NS
+SECTION AUTHORITY
+victim.com.	0	IN SOA . . 1 1 1 1 1
+SECTION ADDITIONAL
+ENTRY_END
+RANGE_END
+
+
+STEP 10 QUERY
+ENTRY_BEGIN
+REPLY RD
+SECTION QUESTION
+www.sub.attacker.net. IN A
+ENTRY_END
+
+; in any case we must get SERVFAIL, no deleation works
+STEP 11 CHECK_ANSWER
+ENTRY_BEGIN
+MATCH all
+REPLY QR RD RA SERVFAIL
+SECTION QUESTION
+www.sub.attacker.net. IN A
+SECTION ANSWER
+ENTRY_END
+
+; recursion happens here
+STEP 20 QUERY
+ENTRY_BEGIN
+REPLY RD DO
+SECTION QUESTION
+glueless.trigger.check.max.number.of.upstream.queries. IN TXT
+ENTRY_END
+
+STEP 21 CHECK_ANSWER
+ENTRY_BEGIN
+MATCH all
+REPLY QR AA RD RA NOERROR
+SECTION QUESTION
+glueless.trigger.check.max.number.of.upstream.queries. IN TXT
+SECTION ANSWER
+glueless.trigger.check.max.number.of.upstream.queries. IN TXT "pass"
+SECTION AUTHORITY
+SECTION ADDITIONAL
+ENTRY_END
+
+
+SCENARIO_END
diff --git a/lib/layer/test.integr/iter_limit_refuse.rpl b/lib/layer/test.integr/iter_limit_refuse.rpl
new file mode 100644
index 0000000..285b5af
--- /dev/null
+++ b/lib/layer/test.integr/iter_limit_refuse.rpl
@@ -0,0 +1,150 @@
+do-ip6: no
+; config options
+;server:
+	stub-addr: 193.0.14.129 	# K.ROOT-SERVERS.NET.
+CONFIG_END
+
+SCENARIO_BEGIN Outrageous number of auth servers return REFUSED. Simulates NXNSAttack misusing wildcard which points to victim's DNS server. Lua config checks if number of outgoing queries is within limits.
+
+; K.ROOT-SERVERS.NET.
+RANGE_BEGIN 0 100
+	ADDRESS 193.0.14.129
+ENTRY_BEGIN
+MATCH opcode qtype qname
+ADJUST copy_id
+REPLY QR NOERROR
+SECTION QUESTION
+. IN NS
+SECTION ANSWER
+. IN NS	K.ROOT-SERVERS.NET.
+SECTION ADDITIONAL
+K.ROOT-SERVERS.NET.	IN	A	193.0.14.129
+ENTRY_END
+
+ENTRY_BEGIN
+MATCH opcode subdomain
+ADJUST copy_id copy_query
+REPLY QR NOERROR
+SECTION QUESTION
+com. IN A
+SECTION AUTHORITY
+com.	IN NS	a.gtld-servers.net.
+SECTION ADDITIONAL
+a.gtld-servers.net.	IN 	A	192.5.6.30
+ENTRY_END
+RANGE_END
+
+; a.gtld-servers.net.
+RANGE_BEGIN 0 100
+	ADDRESS 192.5.6.30
+ENTRY_BEGIN
+MATCH opcode qtype qname
+ADJUST copy_id
+REPLY QR NOERROR
+SECTION QUESTION
+com. IN NS
+SECTION ANSWER
+com.    IN NS   a.gtld-servers.net.
+SECTION ADDITIONAL
+a.gtld-servers.net.     IN      A       192.5.6.30
+ENTRY_END
+
+ENTRY_BEGIN
+MATCH opcode subdomain
+ADJUST copy_id copy_query
+REPLY QR NOERROR
+SECTION QUESTION
+example.com. IN A
+SECTION AUTHORITY
+example.com.	IN NS	ns10.example.com.
+example.com.	IN NS	ns11.example.com.
+example.com.	IN NS	ns12.example.com.
+example.com.	IN NS	ns13.example.com.
+example.com.	IN NS	ns14.example.com.
+example.com.	IN NS	ns15.example.com.
+example.com.	IN NS	ns16.example.com.
+example.com.	IN NS	ns17.example.com.
+example.com.	IN NS	ns18.example.com.
+example.com.	IN NS	ns19.example.com.
+SECTION ADDITIONAL
+ns10.example.com.		IN 	A	1.2.3.10
+ns11.example.com.		IN 	A	1.2.3.11
+ns12.example.com.		IN 	A	1.2.3.12
+ns13.example.com.		IN 	A	1.2.3.13
+ns14.example.com.		IN 	A	1.2.3.14
+ns15.example.com.		IN 	A	1.2.3.15
+ns16.example.com.		IN 	A	1.2.3.16
+ns17.example.com.		IN 	A	1.2.3.17
+ns18.example.com.		IN 	A	1.2.3.18
+ns19.example.com.		IN 	A	1.2.3.19
+
+ENTRY_END
+RANGE_END
+
+; ns1.example.com.
+RANGE_BEGIN 0 100
+	ADDRESS 1.2.3.10
+	ADDRESS 1.2.3.11
+	ADDRESS 1.2.3.12
+	ADDRESS 1.2.3.13
+	ADDRESS 1.2.3.14
+	ADDRESS 1.2.3.15
+	ADDRESS 1.2.3.16
+	ADDRESS 1.2.3.17
+	ADDRESS 1.2.3.18
+	ADDRESS 1.2.3.19
+ENTRY_BEGIN
+MANDATORY
+MATCH opcode qtype qname
+ADJUST copy_id
+REPLY QR AA REFUSED
+SECTION QUESTION
+www.example.com. IN A
+SECTION ANSWER
+SECTION AUTHORITY
+SECTION ADDITIONAL
+ENTRY_END
+RANGE_END
+
+
+; recursion happens here
+STEP 10 QUERY
+ENTRY_BEGIN
+REPLY RD DO
+SECTION QUESTION
+www.example.com. IN A
+ENTRY_END
+
+; in any case we must get SERVFAIL, no auth works
+STEP 11 CHECK_ANSWER
+ENTRY_BEGIN
+MATCH all
+REPLY QR RD RA DO SERVFAIL
+SECTION QUESTION
+www.example.com. IN A
+SECTION ANSWER
+SECTION AUTHORITY
+SECTION ADDITIONAL
+ENTRY_END
+
+; recursion happens here
+STEP 20 QUERY
+ENTRY_BEGIN
+REPLY RD DO
+SECTION QUESTION
+refused.trigger.check.max.number.of.upstream.queries. IN TXT
+ENTRY_END
+
+STEP 21 CHECK_ANSWER
+ENTRY_BEGIN
+MATCH all
+REPLY QR AA RD RA NOERROR
+SECTION QUESTION
+refused.trigger.check.max.number.of.upstream.queries. IN TXT
+SECTION ANSWER
+refused.trigger.check.max.number.of.upstream.queries. IN TXT "pass"
+SECTION AUTHORITY
+SECTION ADDITIONAL
+ENTRY_END
+
+SCENARIO_END
diff --git a/lib/layer/test.integr/kresd_config.j2 b/lib/layer/test.integr/kresd_config.j2
new file mode 100644
index 0000000..57db6e1
--- /dev/null
+++ b/lib/layer/test.integr/kresd_config.j2
@@ -0,0 +1,105 @@
+-- SPDX-License-Identifier: GPL-3.0-or-later
+
+-- hook for iter_refuse_toomany.rpl
+local function check_max_number_of_upstream_queries(maxcnt)
+	return function (state, req)
+		local vals = worker.stats()
+		local upstream_packets = vals.ipv4 + vals.ipv6
+		log('%d packets sent to upstream', upstream_packets)
+		local answ_f
+		if upstream_packets > maxcnt then  -- . + com. + ????
+			answ_f = policy.ANSWER(
+				{ [kres.type.TXT] = { ttl=300, rdata='\4fail' } })
+
+		else
+			answ_f = policy.ANSWER(
+				{ [kres.type.TXT] = { ttl=300, rdata='\4pass' } })
+		end
+		return answ_f(state, req)
+	end
+end
+
+policy.add(
+	policy.suffix(check_max_number_of_upstream_queries(8),
+		policy.todnames({'refused.trigger.check.max.number.of.upstream.queries.'})
+	)
+)
+policy.add(
+	policy.suffix(check_max_number_of_upstream_queries(16),
+		policy.todnames({'glueless.trigger.check.max.number.of.upstream.queries.'})
+	)
+)
+
+-- hook end iter_refuse_toomany.rpl
+
+
+trust_anchors.remove('.')
+{% for TAF in TRUST_ANCHOR_FILES %}
+-- trust_anchors.add_file('{{TAF}}')
+{% endfor %}
+
+{% raw %}
+-- Disable RFC5011 TA update
+if ta_update then
+        modules.unload('ta_update')
+end
+
+-- Disable RFC8145 signaling, scenario doesn't provide expected answers
+if ta_signal_query then
+        modules.unload('ta_signal_query')
+end
+
+-- Disable RFC8109 priming, scenario doesn't provide expected answers
+if priming then
+        modules.unload('priming')
+end
+
+-- Disable this module because it make one priming query
+if detect_time_skew then
+        modules.unload('detect_time_skew')
+end
+
+_hint_root_file('hints')
+cache.size = 2*MB
+verbose(true)
+policy.add(policy.all(policy.DEBUG_ALWAYS))
+{% endraw %}
+
+net = { '{{SELF_ADDR}}' }
+
+{% if DO_IP6 == "true" %}
+net.ipv6 = true
+{% else %}
+net.ipv6 = false
+{% endif %}
+
+{% if DO_IP4 == "true" %}
+net.ipv4 = true
+{% else %}
+net.ipv4 = false
+{% endif %}
+
+
+{% if QMIN == "false" %}
+option('NO_MINIMIZE', true)
+{% else %}
+option('NO_MINIMIZE', false)
+{% endif %}
+
+
+-- Self-checks on globals
+assert(help() ~= nil)
+assert(worker.id ~= nil)
+-- Self-checks on facilities
+assert(cache.count() == 0)
+assert(cache.stats() ~= nil)
+assert(cache.backends() ~= nil)
+assert(worker.stats() ~= nil)
+assert(net.interfaces() ~= nil)
+-- Self-checks on loaded stuff
+assert(net.list()[1].transport.ip == '{{SELF_ADDR}}')
+assert(#modules.list() > 0)
+-- Self-check timers
+ev = event.recurrent(1 * sec, function (ev) return 1 end)
+event.cancel(ev)
+ev = event.after(0, function (ev) return 1 end)
diff --git a/lib/layer/validate.c b/lib/layer/validate.c
new file mode 100644
index 0000000..cf5dda2
--- /dev/null
+++ b/lib/layer/validate.c
@@ -0,0 +1,1257 @@
+/*  Copyright (C) 2014-2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#include <assert.h>
+#include <errno.h>
+#include <sys/time.h>
+#include <stdio.h>
+#include <string.h>
+
+#include <contrib/cleanup.h>
+#include <libknot/packet/wire.h>
+#include <libknot/rrtype/rdname.h>
+#include <libknot/rrtype/rrsig.h>
+#include <libdnssec/error.h>
+
+#include "lib/dnssec/nsec.h"
+#include "lib/dnssec/nsec3.h"
+#include "lib/dnssec.h"
+#include "lib/layer.h"
+#include "lib/resolve.h"
+#include "lib/rplan.h"
+#include "lib/utils.h"
+#include "lib/defines.h"
+#include "lib/module.h"
+#include "lib/selection.h"
+
+#define VERBOSE_MSG(qry, ...) QRVERBOSE(qry, "vldr", __VA_ARGS__)
+
+#define MAX_REVALIDATION_CNT 2
+
+/**
+ * Search in section for given type.
+ * @param sec  Packet section.
+ * @param type Type to search for.
+ * @return     True if found.
+ */
+static bool section_has_type(const knot_pktsection_t *sec, uint16_t type)
+{
+	if (!sec) {
+		return false;
+	}
+
+	for (unsigned i = 0; i < sec->count; ++i) {
+		const knot_rrset_t *rr = knot_pkt_rr(sec, i);
+		if (rr->type == type) {
+			return true;
+		}
+	}
+
+	return false;
+}
+
+static bool pkt_has_type(const knot_pkt_t *pkt, uint16_t type)
+{
+	if (!pkt) {
+		return false;
+	}
+
+	if (section_has_type(knot_pkt_section(pkt, KNOT_ANSWER), type)) {
+		return true;
+	}
+	if (section_has_type(knot_pkt_section(pkt, KNOT_AUTHORITY), type)) {
+		return true;
+	}
+	return section_has_type(knot_pkt_section(pkt, KNOT_ADDITIONAL), type);
+}
+
+static void log_bogus_rrsig(kr_rrset_validation_ctx_t *vctx, const struct kr_query *qry,
+			    const knot_rrset_t *rr, const char *msg) {
+	WITH_VERBOSE(qry) {
+		auto_free char *name_text = kr_dname_text(rr->owner);
+		auto_free char *type_text = kr_rrtype_text(rr->type);
+		VERBOSE_MSG(qry, ">< %s: %s %s "
+			    "(%u matching RRSIGs, %u expired, %u not yet valid, "
+			    "%u invalid signer, %u invalid label count, %u invalid key, "
+			    "%u invalid crypto, %u invalid NSEC)\n",
+			    msg, name_text, type_text, vctx->rrs_counters.matching_name_type,
+			    vctx->rrs_counters.expired, vctx->rrs_counters.notyet,
+			    vctx->rrs_counters.signer_invalid, vctx->rrs_counters.labels_invalid,
+			    vctx->rrs_counters.key_invalid, vctx->rrs_counters.crypto_invalid,
+			    vctx->rrs_counters.nsec_invalid);
+	}
+}
+
+/** Check that given CNAME could be generated by given DNAME (no DNSSEC validation). */
+static bool cname_matches_dname(const knot_rrset_t *rr_cn, const knot_rrset_t *rr_dn)
+{
+	assert(rr_cn->type == KNOT_RRTYPE_CNAME && rr_dn->type == KNOT_RRTYPE_DNAME);
+	/* When DNAME substitution happens, let's consider the "prefix"
+	 * that is carried over and the "suffix" that is replaced.
+	 * (Here we consider the label order used in wire and presentation.) */
+	const int prefix_labels = knot_dname_in_bailiwick(rr_cn->owner, rr_dn->owner);
+	if (prefix_labels < 1)
+		return false;
+	const knot_dname_t *cn_target = knot_cname_name(rr_cn->rrs.rdata);
+	const knot_dname_t *dn_target = knot_dname_target(rr_dn->rrs.rdata);
+		/* ^ We silently use the first RR in each RRset.  Could be e.g. logged. */
+	/* Check that the suffixes are correct - and even prefix label counts. */
+	if (knot_dname_in_bailiwick(cn_target, dn_target) != prefix_labels)
+		return false;
+	/* Check that prefixes match.  Find end of the first one and compare. */
+	const knot_dname_t *cn_se = rr_cn->owner;
+	for (int i = 0; i < prefix_labels; ++i)
+		cn_se += 1 + *cn_se;
+	return strncmp((const char *)rr_cn->owner, (const char *)cn_target,
+			cn_se - rr_cn->owner) == 0;
+		/* ^ We use the fact that dnames are always zero-terminated
+		 * to avoid any possible over-read in cn_target. */
+}
+
+static void mark_insecure_parents(const struct kr_query *qry);
+static void rank_records(struct kr_query *qry, bool any_rank, enum kr_rank rank_to_set,
+			 const knot_dname_t *bailiwick);
+
+static bool maybe_downgrade_nsec3(const ranked_rr_array_entry_t *e, struct kr_query *qry,
+				  const kr_rrset_validation_ctx_t *vctx)
+{
+	bool required_conditions =
+		e->rr->type == KNOT_RRTYPE_NSEC3
+		&& kr_rank_test(e->rank, KR_RANK_SECURE)
+		// extra careful: avoid downgrade if SNAME isn't in bailiwick of signer
+		&& knot_dname_in_bailiwick(qry->sname, vctx->zone_name) >= 0;
+	if (!required_conditions)
+		return false;
+
+	const knot_rdataset_t *rrs = &e->rr->rrs;
+	knot_rdata_t *rd = rrs->rdata;
+	for (int j = 0; j < rrs->count; ++j, rd = knot_rdataset_next(rd)) {
+		if (knot_nsec3_iters(rd) > KR_NSEC3_MAX_ITERATIONS)
+			goto do_downgrade;
+	}
+	return false;
+
+do_downgrade: // we do this deep inside calls because of having signer name available
+	VERBOSE_MSG(qry, "<= DNSSEC downgraded due to NSEC3 iterations %d > %d\n",
+			(int)knot_nsec3_iters(rd), (int)KR_NSEC3_MAX_ITERATIONS);
+	qry->flags.DNSSEC_WANT = false;
+	qry->flags.DNSSEC_INSECURE = true;
+	rank_records(qry, true, KR_RANK_INSECURE, vctx->zone_name);
+	mark_insecure_parents(qry);
+	return true;
+}
+
+#define KNOT_EDOWNGRADED (KNOT_ERROR_MIN - 1)
+
+static int validate_section(kr_rrset_validation_ctx_t *vctx, struct kr_query *qry,
+			    knot_mm_t *pool)
+{
+	if (!vctx) {
+		return kr_error(EINVAL);
+	}
+
+	/* Can't use qry->zone_cut.name directly, as this name can
+	 * change when updating cut information before validation.
+	 */
+	vctx->zone_name = vctx->keys ? vctx->keys->owner : NULL;
+
+	for (ssize_t i = 0; i < vctx->rrs->len; ++i) {
+		ranked_rr_array_entry_t *entry = vctx->rrs->at[i];
+		knot_rrset_t * const rr = entry->rr;
+
+		if (entry->yielded || vctx->qry_uid != entry->qry_uid) {
+			continue;
+		}
+
+		if (kr_rank_test(entry->rank, KR_RANK_OMIT)
+		    || kr_rank_test(entry->rank, KR_RANK_SECURE)) {
+			continue; /* these are already OK */
+		}
+
+		if (rr->type == KNOT_RRTYPE_RRSIG) {
+			const knot_dname_t *signer_name = knot_rrsig_signer_name(rr->rrs.rdata);
+			if (!knot_dname_is_equal(vctx->zone_name, signer_name)) {
+				kr_rank_set(&entry->rank, KR_RANK_MISMATCH);
+				vctx->err_cnt += 1;
+				break;
+			}
+			if (!kr_rank_test(entry->rank, KR_RANK_BOGUS))
+				kr_rank_set(&entry->rank, KR_RANK_OMIT);
+			continue;
+		}
+
+		uint8_t rank_orig = entry->rank;
+		int validation_result = kr_rrset_validate(vctx, rr);
+
+		/* Handle the case of CNAMEs synthesized from DNAMEs (they don't have RRSIGs). */
+		if (rr->type == KNOT_RRTYPE_CNAME && validation_result == kr_error(ENOENT)) {
+			for (ssize_t j = 0; j < vctx->rrs->len; ++j) {
+				ranked_rr_array_entry_t *e_dname = vctx->rrs->at[j];
+				if ((e_dname->rr->type == KNOT_RRTYPE_DNAME)
+				    /* If the order is wrong, we will need two passes. */
+				    && kr_rank_test(e_dname->rank, KR_RANK_SECURE)
+				    && cname_matches_dname(rr, e_dname->rr)) {
+					/* Now we believe the CNAME is OK. */
+					validation_result = kr_ok();
+					break;
+				}
+			}
+			if (validation_result != kr_ok()) {
+				vctx->cname_norrsig_cnt += 1;
+			}
+		}
+
+		if (validation_result == kr_ok()) {
+			kr_rank_set(&entry->rank, KR_RANK_SECURE);
+
+			/* Downgrade zone to insecure if certain NSEC3 record occurs. */
+			if (unlikely(maybe_downgrade_nsec3(entry, qry, vctx)))
+				return kr_error(KNOT_EDOWNGRADED);
+
+		} else if (kr_rank_test(rank_orig, KR_RANK_TRY)) {
+			/* RFC 4035 section 2.2:
+			 * NS RRsets that appear at delegation points (...)
+			 * MUST NOT be signed */
+			if (vctx->rrs_counters.matching_name_type > 0)
+				log_bogus_rrsig(vctx, qry, rr,
+					"found unexpected signatures for non-authoritative data which failed to validate, continuing");
+			vctx->result = kr_ok();
+			kr_rank_set(&entry->rank, KR_RANK_TRY);
+			/* ^^ BOGUS would be more accurate, but it might change
+			 * to MISMATCH on revalidation, e.g. in test val_referral_nods :-/
+			 */
+
+		} else if (validation_result == kr_error(ENOENT)
+				&& vctx->rrs_counters.matching_name_type == 0) {
+			/* no RRSIGs found */
+			kr_rank_set(&entry->rank, KR_RANK_MISSING);
+			vctx->err_cnt += 1;
+			log_bogus_rrsig(vctx, qry, rr, "no valid RRSIGs found");
+		} else {
+			kr_rank_set(&entry->rank, KR_RANK_BOGUS);
+			vctx->err_cnt += 1;
+			log_bogus_rrsig(vctx, qry, rr, "bogus signatures");
+		}
+	}
+	return kr_ok();
+}
+
+static int validate_records(struct kr_request *req, knot_pkt_t *answer, knot_mm_t *pool, bool has_nsec3)
+{
+	struct kr_query *qry = req->current_query;
+	if (!qry->zone_cut.key) {
+		VERBOSE_MSG(qry, "<= no DNSKEY, can't validate\n");
+		return kr_error(EBADMSG);
+	}
+
+	kr_rrset_validation_ctx_t vctx = {
+		.pkt		= answer,
+		.rrs		= &req->answ_selected,
+		.section_id	= KNOT_ANSWER,
+		.keys		= qry->zone_cut.key,
+		.zone_name	= qry->zone_cut.name,
+		.timestamp	= qry->timestamp.tv_sec,
+		.qry_uid	= qry->uid,
+		.has_nsec3	= has_nsec3,
+		.flags		= 0,
+		.err_cnt	= 0,
+		.cname_norrsig_cnt = 0,
+		.result		= 0
+	};
+
+	int ret = validate_section(&vctx, qry, pool);
+	if (vctx.err_cnt && vctx.err_cnt == vctx.cname_norrsig_cnt) {
+		VERBOSE_MSG(qry, ">< all validation errors are missing RRSIGs on CNAMES, trying again in hope for DNAMEs\n");
+		vctx.err_cnt = vctx.cname_norrsig_cnt = vctx.result = 0;
+		ret = validate_section(&vctx, qry, pool);
+	}
+	req->answ_validated = (vctx.err_cnt == 0);
+	if (ret != kr_ok()) {
+		return ret;
+	}
+
+	uint32_t an_flags = vctx.flags;
+	vctx.rrs	  = &req->auth_selected;
+	vctx.section_id   = KNOT_AUTHORITY;
+	vctx.flags	  = 0;
+	vctx.err_cnt	  = 0;
+	vctx.result	  = 0;
+
+	ret = validate_section(&vctx, qry, pool);
+	req->auth_validated = (vctx.err_cnt == 0);
+	if (ret != kr_ok()) {
+		return ret;
+	}
+
+	/* Records were validated.
+	 * If there is wildcard expansion in answer,
+	 * or optout - flag the query.
+         */
+	if (an_flags & KR_DNSSEC_VFLG_WEXPAND) {
+		qry->flags.DNSSEC_WEXPAND = true;
+	}
+	if (an_flags & KR_DNSSEC_VFLG_OPTOUT) {
+		qry->flags.DNSSEC_OPTOUT = true;
+	}
+
+	return ret;
+}
+
+static int validate_keyset(struct kr_request *req, knot_pkt_t *answer, bool has_nsec3)
+{
+	/* Merge DNSKEY records from answer that are below/at current cut. */
+	struct kr_query *qry = req->current_query;
+	bool updated_key = false;
+	const knot_pktsection_t *an = knot_pkt_section(answer, KNOT_ANSWER);
+	for (unsigned i = 0; i < an->count; ++i) {
+		const knot_rrset_t *rr = knot_pkt_rr(an, i);
+		if (rr->type != KNOT_RRTYPE_DNSKEY
+		    || knot_dname_in_bailiwick(rr->owner, qry->zone_cut.name) < 0) {
+			continue;
+		}
+		/* Merge with zone cut (or replace ancestor key). */
+		if (!qry->zone_cut.key || !knot_dname_is_equal(qry->zone_cut.key->owner, rr->owner)) {
+			qry->zone_cut.key = knot_rrset_copy(rr, qry->zone_cut.pool);
+			if (!qry->zone_cut.key) {
+				return kr_error(ENOMEM);
+			}
+			updated_key = true;
+		} else {
+			int ret = knot_rdataset_merge(&qry->zone_cut.key->rrs,
+			                              &rr->rrs, qry->zone_cut.pool);
+			if (ret != 0) {
+				knot_rrset_free(qry->zone_cut.key, qry->zone_cut.pool);
+				qry->zone_cut.key = NULL;
+				return ret;
+			}
+			updated_key = true;
+		}
+	}
+
+	/* Check if there's a key for current TA. */
+	if (updated_key && !(qry->flags.CACHED)) {
+
+		kr_rrset_validation_ctx_t vctx = {
+			.pkt		= answer,
+			.rrs		= &req->answ_selected,
+			.section_id	= KNOT_ANSWER,
+			.keys		= qry->zone_cut.key,
+			.zone_name	= qry->zone_cut.name,
+			.timestamp	= qry->timestamp.tv_sec,
+			.qry_uid	= qry->uid,
+			.has_nsec3	= has_nsec3,
+			.flags		= 0,
+			.result		= 0
+		};
+		int ret = kr_dnskeys_trusted(&vctx, qry->zone_cut.trust_anchor);
+		if (ret != 0) {
+			if (ret != kr_error(DNSSEC_INVALID_DS_ALGORITHM) &&
+			    ret != kr_error(EAGAIN)) {
+				log_bogus_rrsig(&vctx, qry, qry->zone_cut.key, "bogus key");
+			}
+			knot_rrset_free(qry->zone_cut.key, qry->zone_cut.pool);
+			qry->zone_cut.key = NULL;
+			return ret;
+		}
+
+		if (vctx.flags & KR_DNSSEC_VFLG_WEXPAND) {
+			qry->flags.DNSSEC_WEXPAND = true;
+		}
+		if (vctx.flags & KR_DNSSEC_VFLG_OPTOUT) {
+			qry->flags.DNSSEC_OPTOUT = true;
+		}
+
+	}
+	return kr_ok();
+}
+
+static knot_rrset_t *update_ds(struct kr_zonecut *cut, const knot_pktsection_t *sec)
+{
+	/* Aggregate DS records (if using multiple keys) */
+	knot_rrset_t *new_ds = NULL;
+	for (unsigned i = 0; i < sec->count; ++i) {
+		const knot_rrset_t *rr = knot_pkt_rr(sec, i);
+		if (rr->type != KNOT_RRTYPE_DS) {
+			continue;
+		}
+		int ret = 0;
+		if (new_ds) {
+			ret = knot_rdataset_merge(&new_ds->rrs, &rr->rrs, cut->pool);
+		} else {
+			new_ds = knot_rrset_copy(rr, cut->pool);
+			if (!new_ds) {
+				return NULL;
+			}
+		}
+		if (ret != 0) {
+			knot_rrset_free(new_ds, cut->pool);
+			return NULL;
+		}
+	}
+	return new_ds;
+}
+
+static void mark_insecure_parents(const struct kr_query *qry)
+{
+	/* If there is a chain of DS queries mark all of them,
+	 * then mark first non-DS parent.
+	 * Stop if parent is waiting for ns address.
+	 * NS can be located at unsigned zone, but still will return
+	 * valid DNSSEC records for initial query. */
+	struct kr_query *parent = qry->parent;
+	while (parent && !parent->flags.AWAIT_IPV4 && !parent->flags.AWAIT_IPV6) {
+		parent->flags.DNSSEC_WANT = false;
+		parent->flags.DNSSEC_INSECURE = true;
+		if (parent->stype != KNOT_RRTYPE_DS &&
+		    parent->stype != KNOT_RRTYPE_RRSIG) {
+			break;
+		}
+		parent = parent->parent;
+	}
+}
+
+static int update_parent_keys(struct kr_request *req, uint16_t answer_type)
+{
+	struct kr_query *qry = req->current_query;
+	struct kr_query *parent = qry->parent;
+	assert(parent);
+	switch(answer_type) {
+	case KNOT_RRTYPE_DNSKEY:
+		VERBOSE_MSG(qry, "<= parent: updating DNSKEY\n");
+		parent->zone_cut.key = knot_rrset_copy(qry->zone_cut.key, parent->zone_cut.pool);
+		if (!parent->zone_cut.key) {
+			return KR_STATE_FAIL;
+		}
+		break;
+	case KNOT_RRTYPE_DS:
+		VERBOSE_MSG(qry, "<= parent: updating DS\n");
+		if (qry->flags.DNSSEC_INSECURE) { /* DS non-existence proven. */
+			mark_insecure_parents(qry);
+		} else if (qry->flags.DNSSEC_NODS && !qry->flags.FORWARD) {
+			if (qry->flags.DNSSEC_OPTOUT) {
+				mark_insecure_parents(qry);
+			} else {
+				int ret = kr_dnssec_matches_name_and_type(&req->auth_selected, qry->uid,
+									  qry->sname, KNOT_RRTYPE_NS);
+				if (ret == kr_ok()) {
+					mark_insecure_parents(qry);
+				}
+			}
+		} else if (qry->flags.DNSSEC_NODS && qry->flags.FORWARD) {
+			int ret = kr_dnssec_matches_name_and_type(&req->auth_selected, qry->uid,
+								  qry->sname, KNOT_RRTYPE_NS);
+			if (ret == kr_ok()) {
+				mark_insecure_parents(qry);
+			}
+		} else { /* DS existence proven. */
+			parent->zone_cut.trust_anchor = knot_rrset_copy(qry->zone_cut.trust_anchor, parent->zone_cut.pool);
+			if (!parent->zone_cut.trust_anchor) {
+				return KR_STATE_FAIL;
+			}
+		}
+		break;
+	default: break;
+	}
+	return kr_ok();
+}
+
+static int update_delegation(struct kr_request *req, struct kr_query *qry, knot_pkt_t *answer, bool has_nsec3)
+{
+	struct kr_zonecut *cut = &qry->zone_cut;
+
+	/* RFC4035 3.1.4. authoritative must send either DS or proof of non-existence.
+	 * If it contains neither, resolver must query the parent for the DS (RFC4035 5.2.).
+	 * If DS exists, the referral is OK,
+	 * otherwise referral is bogus (or an attempted downgrade attack).
+	 */
+
+
+	unsigned section = KNOT_ANSWER;
+	const bool referral = !knot_wire_get_aa(answer->wire);
+	if (referral) {
+		section = KNOT_AUTHORITY;
+	} else if (knot_pkt_qtype(answer) == KNOT_RRTYPE_DS &&
+		   !(qry->flags.CNAME) &&
+		   (knot_wire_get_rcode(answer->wire) != KNOT_RCODE_NXDOMAIN)) {
+		section = KNOT_ANSWER;
+	} else { /* N/A */
+		return kr_ok();
+	}
+
+	int ret = 0;
+	const knot_dname_t *proved_name = knot_pkt_qname(answer);
+	/* Aggregate DS records (if using multiple keys) */
+	knot_rrset_t *new_ds = update_ds(cut, knot_pkt_section(answer, section));
+	if (!new_ds) {
+		/* No DS provided, check for proof of non-existence. */
+		if (!has_nsec3) {
+			if (referral) {
+				/* Check if it is referral to unsigned, rfc4035 5.2 */
+				ret = kr_nsec_ref_to_unsigned(answer);
+			} else {
+				/* No-data answer */
+				ret = kr_nsec_existence_denial(answer, KNOT_AUTHORITY, proved_name, KNOT_RRTYPE_DS);
+			}
+		} else {
+			if (referral) {
+				/* Check if it is referral to unsigned, rfc5155 8.9 */
+				ret = kr_nsec3_ref_to_unsigned(answer);
+			} else {
+				/* No-data answer, QTYPE is DS, rfc5155 8.6 */
+				ret = kr_nsec3_no_data(answer, KNOT_AUTHORITY, proved_name, KNOT_RRTYPE_DS);
+			}
+			if (ret == kr_error(KNOT_ERANGE)) {
+				/* Not bogus, going insecure due to optout */
+				ret = 0;
+			}
+		}
+
+		if (referral && qry->stype != KNOT_RRTYPE_DS &&
+		    ret == DNSSEC_NOT_FOUND) {
+			/* referral,
+			 * qtype is not KNOT_RRTYPE_DS, NSEC\NSEC3 were not found.
+			 * Check if DS already was fetched. */
+			knot_rrset_t *ta = cut->trust_anchor;
+			if (knot_dname_is_equal(cut->name, ta->owner)) {
+				/* DS is OK */
+				ret = 0;
+			}
+		} else if (ret != 0) {
+			VERBOSE_MSG(qry, "<= bogus proof of DS non-existence\n");
+			qry->flags.DNSSEC_BOGUS = true;
+		} else if (proved_name[0] != '\0') { /* don't go to insecure for . DS */
+			qry->flags.DNSSEC_NODS = true;
+			/* Rank the corresponding nonauth NS as insecure. */
+			for (int i = 0; i < req->auth_selected.len; ++i) {
+				ranked_rr_array_entry_t *ns = req->auth_selected.at[i];
+				if (ns->qry_uid != qry->uid
+				    || !ns->rr
+				    || ns->rr->type != KNOT_RRTYPE_NS) {
+					continue;
+				}
+				if (!referral && !knot_dname_is_equal(qry->sname, ns->rr->owner)) {
+					continue;
+				}
+				/* Found the record.  Note: this is slightly fragile
+				 * in case there were more NS records in the packet.
+				 * As it is now for referrals, kr_nsec*_ref_to_unsigned consider
+				 * (only) the first NS record in the packet. */
+				if (!kr_rank_test(ns->rank, KR_RANK_AUTH)) { /* sanity */
+					ns->rank = KR_RANK_INSECURE;
+				}
+				break;
+			}
+		}
+		return ret;
+	} else if (qry->flags.FORWARD && qry->parent) {
+		struct kr_query *parent = qry->parent;
+		parent->zone_cut.name = knot_dname_copy(qry->sname, parent->zone_cut.pool);
+	}
+
+	/* Extend trust anchor */
+	VERBOSE_MSG(qry, "<= DS: OK\n");
+	cut->trust_anchor = new_ds;
+	return ret;
+}
+
+static const knot_dname_t *find_first_signer(ranked_rr_array_t *arr, struct kr_query *qry)
+{
+	for (size_t i = 0; i < arr->len; ++i) {
+		ranked_rr_array_entry_t *entry = arr->at[i];
+		const knot_rrset_t *rr = entry->rr;
+		if (entry->yielded ||
+		    (!kr_rank_test(entry->rank, KR_RANK_INITIAL) &&
+		     !kr_rank_test(entry->rank, KR_RANK_TRY) &&
+		     !kr_rank_test(entry->rank, KR_RANK_MISMATCH))) {
+			continue;
+		}
+		if (rr->type != KNOT_RRTYPE_RRSIG) {
+			continue;
+		}
+		const knot_dname_t *signame = knot_rrsig_signer_name(rr->rrs.rdata);
+		if (knot_dname_in_bailiwick(rr->owner, signame) >= 0) {
+			return signame;
+		} else {
+			/* otherwise it's some nonsense, so we skip it */
+			kr_log_q(qry, "vldr", "protocol violation: "
+					"out-of-bailwick RRSIG signer, skipping\n");
+		}
+	}
+	return NULL;
+}
+
+static const knot_dname_t *signature_authority(struct kr_request *req)
+{
+	const knot_dname_t *signer_name = find_first_signer(&req->answ_selected, req->current_query);
+	if (!signer_name) {
+		signer_name = find_first_signer(&req->auth_selected, req->current_query);
+	}
+	return signer_name;
+}
+
+static int rrsig_not_found(const kr_layer_t * const ctx, const knot_pkt_t * const pkt,
+				const knot_rrset_t * const rr)
+{
+	/* Signatures are missing.  There might be a zone cut that we've skipped
+	 * and transitions to insecure.  That can commonly happen when iterating
+	 * and both sides of that cut are served by the same IP address(es).
+	 * We'll try proving that the name truly is insecure - by spawning
+	 * a DS sub-query on a suitable QNAME.
+	 */
+	struct kr_request * const req = ctx->req;
+	struct kr_query * const qry = req->current_query;
+
+	if (qry->flags.FORWARD || qry->flags.STUB) {
+		/* Undiscovered signed cuts can't happen in the current forwarding
+		 * algorithm, so this function shouldn't be able to help. */
+		return KR_STATE_FAIL;
+	}
+
+	/* Find cut_next: the name at which to try finding the "missing" zone cut. */
+	const knot_dname_t * const cut_top = qry->zone_cut.name;
+	const int next_depth = knot_dname_in_bailiwick(rr->owner, cut_top);
+	if (next_depth <= 0) {
+		return KR_STATE_FAIL; // shouldn't happen, I think
+	}
+	/* Add one extra label to cur_top, i.e. descend one level below current zone cut */
+	const knot_dname_t * const cut_next = rr->owner +
+		knot_dname_prefixlen(rr->owner, next_depth - 1, NULL);
+
+	/* Spawn that DS sub-query. */
+	struct kr_query * const next = kr_rplan_push(&req->rplan, qry, cut_next,
+						rr->rclass, KNOT_RRTYPE_DS);
+	if (!next) {
+		return KR_STATE_FAIL;
+	}
+	kr_zonecut_init(&next->zone_cut, qry->zone_cut.name, &req->pool);
+	kr_zonecut_copy(&next->zone_cut, &qry->zone_cut);
+	kr_zonecut_copy_trust(&next->zone_cut, &qry->zone_cut);
+	next->flags.DNSSEC_WANT = true;
+	return KR_STATE_YIELD;
+}
+
+static int check_validation_result(kr_layer_t *ctx, const knot_pkt_t *pkt, ranked_rr_array_t *arr)
+{
+	int ret = KR_STATE_DONE;
+	struct kr_request *req = ctx->req;
+	struct kr_query *qry = req->current_query;
+	ranked_rr_array_entry_t *invalid_entry = NULL;
+	for (size_t i = 0; i < arr->len; ++i) {
+		ranked_rr_array_entry_t *entry = arr->at[i];
+		if (entry->yielded || entry->qry_uid != qry->uid) {
+			continue;
+		}
+		if (kr_rank_test(entry->rank, KR_RANK_MISMATCH)) {
+			invalid_entry = entry;
+			break;
+		} else if (kr_rank_test(entry->rank, KR_RANK_MISSING) &&
+			   !invalid_entry) {
+			invalid_entry = entry;
+		} else if (kr_rank_test(entry->rank, KR_RANK_OMIT)) {
+			continue;
+		} else if (!kr_rank_test(entry->rank, KR_RANK_SECURE) &&
+			   !invalid_entry) {
+			invalid_entry = entry;
+		}
+	}
+
+	if (!invalid_entry) {
+		return ret;
+	}
+
+	if (!kr_rank_test(invalid_entry->rank, KR_RANK_SECURE) &&
+	    (++(invalid_entry->revalidation_cnt) > MAX_REVALIDATION_CNT)) {
+		VERBOSE_MSG(qry, "<= continuous revalidation, fails\n");
+		qry->flags.DNSSEC_BOGUS = true;
+		return KR_STATE_FAIL;
+	}
+
+	const knot_rrset_t *rr = invalid_entry->rr;
+	if (kr_rank_test(invalid_entry->rank, KR_RANK_MISMATCH)) {
+		const knot_dname_t *signer_name = knot_rrsig_signer_name(rr->rrs.rdata);
+		if (knot_dname_in_bailiwick(signer_name, qry->zone_cut.name) > 0) {
+			qry->zone_cut.name = knot_dname_copy(signer_name, &req->pool);
+			qry->flags.AWAIT_CUT = true;
+		} else if (!knot_dname_is_equal(signer_name, qry->zone_cut.name)) {
+			if (qry->zone_cut.parent) {
+				memcpy(&qry->zone_cut, qry->zone_cut.parent, sizeof(qry->zone_cut));
+			} else {
+				qry->flags.AWAIT_CUT = true;
+			}
+			qry->zone_cut.name = knot_dname_copy(signer_name, &req->pool);
+		}
+		VERBOSE_MSG(qry, ">< cut changed (new signer), needs revalidation\n");
+		ret = KR_STATE_YIELD;
+	} else if (kr_rank_test(invalid_entry->rank, KR_RANK_MISSING)) {
+		ret = rrsig_not_found(ctx, pkt, rr);
+	} else if (!kr_rank_test(invalid_entry->rank, KR_RANK_SECURE)) {
+		qry->flags.DNSSEC_BOGUS = true;
+		ret = KR_STATE_FAIL;
+	}
+
+	return ret;
+}
+
+static bool check_empty_answer(kr_layer_t *ctx, knot_pkt_t *pkt)
+{
+	struct kr_request *req	= ctx->req;
+	struct kr_query *qry	= req->current_query;
+	ranked_rr_array_t *arr	= &req->answ_selected;
+	size_t num_entries = 0;
+	for (size_t i = 0; i < arr->len; ++i) {
+		ranked_rr_array_entry_t *entry = arr->at[i];
+		const knot_rrset_t *rr = entry->rr;
+		if (rr->type == KNOT_RRTYPE_RRSIG && qry->stype != KNOT_RRTYPE_RRSIG) {
+			continue;
+		}
+		if (entry->qry_uid == qry->uid) {
+			++num_entries;
+		}
+	}
+	const knot_pktsection_t *an = knot_pkt_section(pkt, KNOT_ANSWER);
+	return ((an->count != 0) && (num_entries == 0)) ? false : true;
+}
+
+static int unsigned_forward(kr_layer_t *ctx, knot_pkt_t *pkt)
+{
+	struct kr_request *req = ctx->req;
+	struct kr_query *qry = req->current_query;
+	const uint16_t qtype = knot_pkt_qtype(pkt);
+	const uint8_t pkt_rcode = knot_wire_get_rcode(pkt->wire);
+	bool nods = false;
+	bool ns_exist = true;
+	for (int i = 0; i < req->rplan.resolved.len; ++i) {
+		struct kr_query *q = req->rplan.resolved.at[i];
+		if (q->sclass == qry->sclass &&
+		    q->stype == KNOT_RRTYPE_DS &&
+		    knot_dname_is_equal(q->sname, qry->sname)) {
+			nods = true;
+			if (!(q->flags.DNSSEC_OPTOUT)) {
+				int ret = kr_dnssec_matches_name_and_type(&req->auth_selected, q->uid,
+									  qry->sname, KNOT_RRTYPE_NS);
+				ns_exist = (ret == kr_ok());
+			}
+		}
+	}
+
+	if (nods && ns_exist && qtype == KNOT_RRTYPE_NS) {
+		qry->flags.DNSSEC_WANT = false;
+		qry->flags.DNSSEC_INSECURE = true;
+		if (qry->forward_flags.CNAME) {
+			assert(qry->cname_parent);
+			qry->cname_parent->flags.DNSSEC_WANT = false;
+			qry->cname_parent->flags.DNSSEC_INSECURE = true;
+		} else if (pkt_rcode == KNOT_RCODE_NOERROR && qry->parent != NULL) {
+			const knot_pktsection_t *sec = knot_pkt_section(pkt, KNOT_ANSWER);
+			const knot_rrset_t *rr = knot_pkt_rr(sec, 0);
+			if (rr->type == KNOT_RRTYPE_NS) {
+				qry->parent->zone_cut.name = knot_dname_copy(rr->owner, &req->pool);
+				qry->parent->flags.DNSSEC_WANT = false;
+				qry->parent->flags.DNSSEC_INSECURE = true;
+			}
+		}
+		while (qry->parent) {
+			qry = qry->parent;
+			qry->flags.DNSSEC_WANT = false;
+			qry->flags.DNSSEC_INSECURE = true;
+			if (qry->forward_flags.CNAME) {
+				assert(qry->cname_parent);
+				qry->cname_parent->flags.DNSSEC_WANT = false;
+				qry->cname_parent->flags.DNSSEC_INSECURE = true;
+			}
+		}
+		return KR_STATE_DONE;
+	}
+
+	if (ctx->state == KR_STATE_YIELD) {
+		return KR_STATE_DONE;
+	}
+
+	if (!nods && qtype != KNOT_RRTYPE_DS) {
+		struct kr_rplan *rplan = &req->rplan;
+		struct kr_query *next = kr_rplan_push(rplan, qry, qry->sname, qry->sclass, KNOT_RRTYPE_DS);
+		if (!next) {
+			return KR_STATE_FAIL;
+		}
+		kr_zonecut_set(&next->zone_cut, qry->zone_cut.name);
+		kr_zonecut_copy_trust(&next->zone_cut, &qry->zone_cut);
+		next->flags.DNSSEC_WANT = true;
+	}
+
+	return KR_STATE_YIELD;
+}
+
+static int check_signer(kr_layer_t *ctx, knot_pkt_t *pkt)
+{
+	struct kr_request *req = ctx->req;
+	struct kr_query *qry = req->current_query;
+	const knot_dname_t *ta_name = qry->zone_cut.trust_anchor ? qry->zone_cut.trust_anchor->owner : NULL;
+	const knot_dname_t *signer = signature_authority(req);
+	if (ta_name && (!signer || !knot_dname_is_equal(ta_name, signer))) {
+		/* check all newly added RRSIGs */
+		if (!signer) {
+			if (qry->flags.FORWARD) {
+				return unsigned_forward(ctx, pkt);
+			}
+			/* Not a DNSSEC-signed response. */
+			if (ctx->state == KR_STATE_YIELD) {
+				/* Already yielded for revalidation.
+				 * It means that trust chain is OK and
+				 * transition to INSECURE hasn't occurred.
+				 * Let the validation logic ask about RRSIG. */
+				return KR_STATE_DONE;
+			}
+			/* Ask parent for DS
+			 * to prove transition to INSECURE. */
+			const uint16_t qtype = knot_pkt_qtype(pkt);
+			const knot_dname_t *qname = knot_pkt_qname(pkt);
+			if (qtype == KNOT_RRTYPE_NS &&
+			    knot_dname_in_bailiwick(qname, qry->zone_cut.name) > 0) {
+				/* Server is authoritative
+				 * for both parent and child,
+				 * and child zone is not signed. */
+				qry->zone_cut.name = knot_dname_copy(qname, &req->pool);
+			}
+		} else if (knot_dname_in_bailiwick(signer, qry->zone_cut.name) > 0) {
+			if (!(qry->flags.FORWARD)) {
+				/* Key signer is below current cut, advance and refetch keys. */
+				qry->zone_cut.name = knot_dname_copy(signer, &req->pool);
+			} else {
+				/* Check if DS does not exist. */
+				struct kr_query *q = kr_rplan_find_resolved(&req->rplan, NULL,
+									    signer, qry->sclass, KNOT_RRTYPE_DS);
+				if (q && q->flags.DNSSEC_NODS) {
+					qry->flags.DNSSEC_WANT = false;
+					qry->flags.DNSSEC_INSECURE = true;
+					if (qry->parent) {
+						qry->parent->flags.DNSSEC_WANT = false;
+						qry->parent->flags.DNSSEC_INSECURE = true;
+					}
+				} else if (qry->stype != KNOT_RRTYPE_DS) {
+					struct kr_rplan *rplan = &req->rplan;
+					struct kr_query *next = kr_rplan_push(rplan, qry, qry->sname,
+									      qry->sclass, KNOT_RRTYPE_DS);
+					if (!next) {
+						return KR_STATE_FAIL;
+					}
+					kr_zonecut_set(&next->zone_cut, qry->zone_cut.name);
+					kr_zonecut_copy_trust(&next->zone_cut, &qry->zone_cut);
+					next->flags.DNSSEC_WANT = true;
+				}
+			}
+		} else if (!knot_dname_is_equal(signer, qry->zone_cut.name)) {
+			/* Key signer is above the current cut, so we can't validate it. This happens when
+			   a server is authoritative for both grandparent, parent and child zone.
+			   Ascend to parent cut, and refetch authority for signer. */
+			if (qry->zone_cut.parent) {
+				memcpy(&qry->zone_cut, qry->zone_cut.parent, sizeof(qry->zone_cut));
+			} else {
+				qry->flags.AWAIT_CUT = true;
+			}
+			qry->zone_cut.name = knot_dname_copy(signer, &req->pool);
+		}
+
+		/* zone cut matches, but DS/DNSKEY doesn't => refetch. */
+		VERBOSE_MSG(qry, ">< cut changed, needs revalidation\n");
+		if ((qry->flags.FORWARD) && qry->stype != KNOT_RRTYPE_DS) {
+			struct kr_rplan *rplan = &req->rplan;
+			struct kr_query *next = kr_rplan_push(rplan, qry, signer,
+							qry->sclass, KNOT_RRTYPE_DS);
+			if (!next) {
+				return KR_STATE_FAIL;
+			}
+			kr_zonecut_set(&next->zone_cut, qry->zone_cut.name);
+			kr_zonecut_copy_trust(&next->zone_cut, &qry->zone_cut);
+			next->flags.DNSSEC_WANT = true;
+			return KR_STATE_YIELD;
+		}
+		if (!(qry->flags.FORWARD)) {
+			return KR_STATE_YIELD;
+		}
+	}
+	return KR_STATE_DONE;
+}
+
+/** Change ranks of RRs from this single iteration:
+ * _INITIAL or _TRY or _MISSING -> rank_to_set.  Or any rank, if any_rank == true.
+ *
+ * Optionally do this only in a `bailiwick` (if not NULL).
+ * Iterator shouldn't have selected such records, but we check to be sure. */
+static void rank_records(struct kr_query *qry, bool any_rank, enum kr_rank rank_to_set,
+			 const knot_dname_t *bailiwick)
+{
+	struct kr_request *req = qry->request;
+	ranked_rr_array_t *ptrs[2] = { &req->answ_selected, &req->auth_selected };
+	for (size_t i = 0; i < 2; ++i) {
+		ranked_rr_array_t *arr = ptrs[i];
+		for (size_t j = 0; j < arr->len; ++j) {
+			ranked_rr_array_entry_t *entry = arr->at[j];
+			if (entry->qry_uid != qry->uid) {
+				continue;
+			}
+			if (bailiwick && knot_dname_in_bailiwick(entry->rr->owner,
+								 bailiwick) < 0) {
+				continue;
+			}
+			if (kr_rank_test(entry->rank, KR_RANK_INITIAL)
+			    || kr_rank_test(entry->rank, KR_RANK_TRY)
+			    || kr_rank_test(entry->rank, KR_RANK_MISSING)) {
+				kr_rank_set(&entry->rank, rank_to_set);
+			}
+		}
+	}
+}
+
+static void check_wildcard(kr_layer_t *ctx)
+{
+	struct kr_request *req	   = ctx->req;
+	struct kr_query *qry	   = req->current_query;
+	ranked_rr_array_t *ptrs[2] = { &req->answ_selected, &req->auth_selected };
+
+	for (int i = 0; i < 2; ++i) {
+		ranked_rr_array_t *arr = ptrs[i];
+		for (ssize_t j = 0; j < arr->len; ++j) {
+			ranked_rr_array_entry_t *entry = arr->at[j];
+			const knot_rrset_t *rrsigs = entry->rr;
+
+			if (qry->uid != entry->qry_uid) {
+				continue;
+			}
+
+			if (rrsigs->type != KNOT_RRTYPE_RRSIG) {
+				continue;
+			}
+
+			int owner_labels = knot_dname_labels(rrsigs->owner, NULL);
+
+			knot_rdata_t *rdata_k = rrsigs->rrs.rdata;
+			for (int k = 0; k < rrsigs->rrs.count;
+					++k, rdata_k = knot_rdataset_next(rdata_k)) {
+				if (knot_rrsig_labels(rdata_k) != owner_labels) {
+					qry->flags.DNSSEC_WEXPAND = true;
+				}
+			}
+		}
+	}
+}
+
+/** Just for wildcard_adjust_to_wire() */
+static bool rr_is_for_wildcard(const ranked_rr_array_entry_t *entry)
+{
+	switch (kr_rrset_type_maysig(entry->rr)) {
+	case KNOT_RRTYPE_NSEC:
+	case KNOT_RRTYPE_NSEC3:
+		return true;
+	default:
+		return false;
+	}
+}
+/** In case of wildcard expansion, mark required authority RRs by to_wire. */
+static int wildcard_adjust_to_wire(struct kr_request *req, const struct kr_query *qry)
+{
+	if (!qry->parent && qry->flags.DNSSEC_WEXPAND) {
+		return kr_ranked_rrarray_set_wire(&req->auth_selected, true,
+				qry->uid, true, &rr_is_for_wildcard);
+	}
+	return kr_ok();
+}
+
+static int validate(kr_layer_t *ctx, knot_pkt_t *pkt)
+{
+	int ret = 0;
+	struct kr_request *req = ctx->req;
+	struct kr_query *qry = req->current_query;
+
+	/* Ignore faulty or unprocessed responses. */
+	if (ctx->state & (KR_STATE_FAIL|KR_STATE_CONSUME)) {
+		return ctx->state;
+	}
+
+	/* Pass-through if user doesn't want secure answer or stub. */
+	if (qry->flags.STUB) {
+		rank_records(qry, false, KR_RANK_OMIT, NULL);
+		return ctx->state;
+	}
+	uint8_t pkt_rcode = knot_wire_get_rcode(pkt->wire);
+	if ((qry->flags.FORWARD) &&
+	    pkt_rcode != KNOT_RCODE_NOERROR &&
+	    pkt_rcode != KNOT_RCODE_NXDOMAIN) {
+		do {
+			qry->flags.DNSSEC_BOGUS = true;
+			if (qry->cname_parent) {
+				qry->cname_parent->flags.DNSSEC_BOGUS = true;
+			}
+			qry = qry->parent;
+		} while (qry);
+		ctx->state = KR_STATE_DONE;
+		return ctx->state;
+	}
+
+	if (!(qry->flags.DNSSEC_WANT)) {
+		const bool is_insec = qry->flags.CACHED && qry->flags.DNSSEC_INSECURE;
+		if ((qry->flags.DNSSEC_INSECURE)) {
+			rank_records(qry, true, KR_RANK_INSECURE, qry->zone_cut.name);
+		}
+		if (is_insec && qry->parent != NULL) {
+			/* We have got insecure answer from cache.
+			 * Mark parent(s) as insecure. */
+			mark_insecure_parents(qry);
+			VERBOSE_MSG(qry, "<= cached insecure response, going insecure\n");
+			ctx->state = KR_STATE_DONE;
+		} else if (ctx->state == KR_STATE_YIELD) {
+			/* Transition to unsecure state
+			   occurred during revalidation.
+			   if state remains YIELD, answer will not be cached.
+			   Let cache layers to work. */
+			ctx->state = KR_STATE_DONE;
+		}
+		return ctx->state;
+	}
+
+	/* Pass-through if CD bit is set. */
+	if (knot_wire_get_cd(req->qsource.packet->wire)) {
+		check_wildcard(ctx);
+		wildcard_adjust_to_wire(req, qry);
+		rank_records(qry, false, KR_RANK_OMIT, NULL);
+		return ctx->state;
+	}
+	/* Answer for RRSIG may not set DO=1, but all records MUST still validate. */
+	bool use_signatures = (knot_pkt_qtype(pkt) != KNOT_RRTYPE_RRSIG);
+	if (!(qry->flags.CACHED) && !knot_pkt_has_dnssec(pkt) && !use_signatures) {
+		VERBOSE_MSG(qry, "<= got insecure response\n");
+		qry->flags.DNSSEC_BOGUS = true;
+		return KR_STATE_FAIL;
+	}
+
+	/* Check if this is a DNSKEY answer, check trust chain and store. */
+	uint16_t qtype = knot_pkt_qtype(pkt);
+	bool has_nsec3 = pkt_has_type(pkt, KNOT_RRTYPE_NSEC3);
+	const knot_pktsection_t *an = knot_pkt_section(pkt, KNOT_ANSWER);
+	const bool referral = (an->count == 0 && !knot_wire_get_aa(pkt->wire));
+
+	if (!(qry->flags.CACHED) && knot_wire_get_aa(pkt->wire)) {
+		/* Check if answer if not empty,
+		 * but iterator has not selected any records. */
+		if (!check_empty_answer(ctx, pkt)) {
+			VERBOSE_MSG(qry, "<= no useful RR in authoritative answer\n");
+			qry->flags.DNSSEC_BOGUS = true;
+			return KR_STATE_FAIL;
+		}
+		/* Track difference between current TA and signer name.
+		 * This indicates that the NS is auth for both parent-child,
+		 * and we must update DS/DNSKEY to validate it.
+		 */
+		ret = check_signer(ctx, pkt);
+		if (ret != KR_STATE_DONE) {
+			return ret;
+		}
+		if (qry->flags.FORWARD && qry->flags.DNSSEC_INSECURE) {
+			return KR_STATE_DONE;
+		}
+	}
+
+	if (knot_wire_get_aa(pkt->wire) && qtype == KNOT_RRTYPE_DNSKEY) {
+		const knot_rrset_t *ds = qry->zone_cut.trust_anchor;
+		if (ds && !kr_ds_algo_support(ds)) {
+			VERBOSE_MSG(qry, ">< all DS entries use unsupported algorithm pairs, going insecure\n");
+			/* ^ the message is a bit imprecise to avoid being too verbose */
+			qry->flags.DNSSEC_WANT = false;
+			qry->flags.DNSSEC_INSECURE = true;
+			rank_records(qry, true, KR_RANK_INSECURE, qry->zone_cut.name);
+			mark_insecure_parents(qry);
+			return KR_STATE_DONE;
+		}
+
+		ret = validate_keyset(req, pkt, has_nsec3);
+		if (ret == kr_error(EAGAIN)) {
+			VERBOSE_MSG(qry, ">< cut changed, needs revalidation\n");
+			return KR_STATE_YIELD;
+		} else if (ret != 0) {
+			VERBOSE_MSG(qry, "<= bad keys, broken trust chain\n");
+			qry->flags.DNSSEC_BOGUS = true;
+			return KR_STATE_FAIL;
+		}
+	}
+
+	/* Validate all records, fail as bogus if it doesn't match.
+	 * Do not revalidate data from cache, as it's already trusted.
+	 * TTLs of RRsets may get lowered. */
+	if (!(qry->flags.CACHED)) {
+		ret = validate_records(req, pkt, req->rplan.pool, has_nsec3);
+		if (ret == KNOT_EDOWNGRADED) {
+			return KR_STATE_DONE;
+		} else if (ret != 0) {
+			/* something exceptional - no DNS key, empty pointers etc
+			 * normally it shoudn't happen */
+			VERBOSE_MSG(qry, "<= couldn't validate RRSIGs\n");
+			qry->flags.DNSSEC_BOGUS = true;
+			return KR_STATE_FAIL;
+		}
+		/* check validation state and spawn subrequests */
+		if (!req->answ_validated) {
+			ret = check_validation_result(ctx, pkt, &req->answ_selected);
+			if (ret != KR_STATE_DONE) {
+				return ret;
+			}
+		}
+		if (!req->auth_validated) {
+			ret = check_validation_result(ctx, pkt, &req->auth_selected);
+			if (ret != KR_STATE_DONE) {
+				return ret;
+			}
+		}
+	}
+
+	/* Validate non-existence proof if not positive answer.
+	 * In case of CNAME, iterator scheduled a sibling query for the target,
+	 * so we just drop the negative piece of information and don't try to prove it.
+	 * TODO: not ideal; with aggressive cache we'll at least avoid the extra packet. */
+	if (!qry->flags.CACHED && pkt_rcode == KNOT_RCODE_NXDOMAIN && !qry->flags.CNAME) {
+		/* @todo If knot_pkt_qname(pkt) is used instead of qry->sname then the tests crash. */
+		if (!has_nsec3) {
+			ret = kr_nsec_name_error_response_check(pkt, KNOT_AUTHORITY, qry->sname);
+		} else {
+			ret = kr_nsec3_name_error_response_check(pkt, KNOT_AUTHORITY, qry->sname);
+		}
+		if (has_nsec3 && (ret == kr_error(KNOT_ERANGE))) {
+			/* NXDOMAIN proof is OK,
+			 * but NSEC3 that covers next closer name
+			 * (or wildcard at next closer name) has opt-out flag.
+			 * RFC5155 9.2; AD flag can not be set */
+			qry->flags.DNSSEC_OPTOUT = true;
+			VERBOSE_MSG(qry, "<= can't prove NXDOMAIN due to optout, going insecure\n");
+		} else if (ret != 0) {
+			VERBOSE_MSG(qry, "<= bad NXDOMAIN proof\n");
+			qry->flags.DNSSEC_BOGUS = true;
+			return KR_STATE_FAIL;
+		}
+	}
+
+	/* @todo WTH, this needs API that just tries to find a proof and the caller
+	 * doesn't have to worry about NSEC/NSEC3
+	 * @todo rework this
+	 * CNAME: same as the NXDOMAIN case above */
+	if (!qry->flags.CACHED && pkt_rcode == KNOT_RCODE_NOERROR && !qry->flags.CNAME) {
+		bool no_data = (an->count == 0 && knot_wire_get_aa(pkt->wire));
+		if (no_data) {
+			/* @todo
+			 * ? quick mechanism to determine which check to preform first
+			 * ? merge the functionality together to share code/resources
+			 */
+			if (!has_nsec3) {
+				ret = kr_nsec_existence_denial(pkt, KNOT_AUTHORITY, knot_pkt_qname(pkt), knot_pkt_qtype(pkt));
+			} else {
+				ret = kr_nsec3_no_data(pkt, KNOT_AUTHORITY, knot_pkt_qname(pkt), knot_pkt_qtype(pkt));
+			}
+			if (ret != 0) {
+				if (has_nsec3 && (ret == kr_error(KNOT_ERANGE))) {
+					VERBOSE_MSG(qry, "<= can't prove NODATA due to optout, going insecure\n");
+					qry->flags.DNSSEC_OPTOUT = true;
+					/* Could not return from here,
+					 * we must continue, validate NSEC\NSEC3 and
+					 * call update_parent_keys() to mark
+					 * parent queries as insecured */
+				} else {
+					VERBOSE_MSG(qry, "<= bad NODATA proof\n");
+					qry->flags.DNSSEC_BOGUS = true;
+					return KR_STATE_FAIL;
+				}
+			}
+		}
+	}
+
+	wildcard_adjust_to_wire(req, qry);
+
+	/* Check and update current delegation point security status. */
+	ret = update_delegation(req, qry, pkt, has_nsec3);
+	if (ret == DNSSEC_NOT_FOUND && qry->stype != KNOT_RRTYPE_DS) {
+		if (ctx->state == KR_STATE_YIELD) {
+			VERBOSE_MSG(qry, "<= can't validate referral\n");
+			qry->flags.DNSSEC_BOGUS = true;
+			return KR_STATE_FAIL;
+		} else {
+			/* Check the trust chain and query DS\DNSKEY if needed. */
+			VERBOSE_MSG(qry, "<= DS\\NSEC was not found, querying for DS\n");
+			return KR_STATE_YIELD;
+		}
+	} else if (ret != 0) {
+		return KR_STATE_FAIL;
+	} else if (pkt_rcode == KNOT_RCODE_NOERROR &&
+		   referral &&
+		   ((!qry->flags.DNSSEC_WANT && qry->flags.DNSSEC_INSECURE) ||
+		   (qry->flags.DNSSEC_NODS))) {
+		/* referral with proven DS non-existance */
+		qtype = KNOT_RRTYPE_DS;
+	}
+	/* Update parent query zone cut */
+	if (qry->parent) {
+		if (update_parent_keys(req, qtype) != 0) {
+			return KR_STATE_FAIL;
+		}
+	}
+
+	if (qry->flags.FORWARD && qry->parent) {
+		if (pkt_rcode == KNOT_RCODE_NXDOMAIN) {
+			qry->parent->forward_flags.NO_MINIMIZE = true;
+		}
+	}
+	VERBOSE_MSG(qry, "<= answer valid, OK\n");
+	return KR_STATE_DONE;
+}
+
+/** Hide RRsets which did not validate from clients. */
+static int hide_bogus(kr_layer_t *ctx) {
+	if (knot_wire_get_cd(ctx->req->qsource.packet->wire)) {
+		return ctx->state;
+	}
+	/* We don't want to send bogus answers to clients, not even in SERVFAIL
+	 * answers, but we cannot drop whole sections. If a CNAME chain
+	 * SERVFAILs somewhere, the steps that were OK should be put into
+	 * answer.
+	 *
+	 * There is one specific issue: currently we follow CNAME *before*
+	 * we validate it, because... iterator comes before validator.
+	 * Therefore some rrsets might be added into req->*_selected before
+	 * we detected failure in validator.
+	 * TODO: better approach, probably during work on parallel queries.
+	 */
+	const ranked_rr_array_t *sel[] = kr_request_selected(ctx->req);
+	for (knot_section_t sect = KNOT_ANSWER; sect <= KNOT_ADDITIONAL; ++sect) {
+		for (size_t i = 0; i < sel[sect]->len; ++i) {
+			ranked_rr_array_entry_t *e = sel[sect]->at[i];
+			e->to_wire = e->to_wire
+				&& !kr_rank_test(e->rank, KR_RANK_INDET)
+				&& !kr_rank_test(e->rank, KR_RANK_BOGUS)
+				&& !kr_rank_test(e->rank, KR_RANK_MISMATCH)
+				&& !kr_rank_test(e->rank, KR_RANK_MISSING);
+		}
+	}
+	return ctx->state;
+}
+
+static int validate_wrapper(kr_layer_t *ctx, knot_pkt_t *pkt) {
+	// Wrapper for now.
+	int ret = validate(ctx, pkt);
+	struct kr_request *req = ctx->req;
+	struct kr_query *qry = req->current_query;
+	if (ret & KR_STATE_FAIL && qry->flags.DNSSEC_BOGUS)
+		qry->server_selection.error(qry, req->upstream.transport, KR_SELECTION_DNSSEC_ERROR);
+	return ret;
+}
+
+
+/** Module implementation. */
+int validate_init(struct kr_module *self)
+{
+	static const kr_layer_api_t layer = {
+		.consume = &validate_wrapper,
+		.answer_finalize = &hide_bogus,
+	};
+	self->layer = &layer;
+	return kr_ok();
+}
+
+KR_MODULE_EXPORT(validate) /* useless for builtin module, but let's be consistent */
+
+#undef VERBOSE_MSG
diff --git a/lib/layer/validate.test.integr/deckard.yaml b/lib/layer/validate.test.integr/deckard.yaml
new file mode 100644
index 0000000..aac7b20
--- /dev/null
+++ b/lib/layer/validate.test.integr/deckard.yaml
@@ -0,0 +1,10 @@
+# SPDX-License-Identifier: GPL-3.0-or-later
+programs:
+- name: kresd
+  binary: kresd
+  additional:
+    - -n
+  templates:
+    - lib/layer/validate.test.integr/kresd_config.j2
+  configs:
+    - config
diff --git a/lib/layer/validate.test.integr/fwd_insecure_but_rrsig_signer_invalid.rpl b/lib/layer/validate.test.integr/fwd_insecure_but_rrsig_signer_invalid.rpl
new file mode 100644
index 0000000..3cc0968
--- /dev/null
+++ b/lib/layer/validate.test.integr/fwd_insecure_but_rrsig_signer_invalid.rpl
@@ -0,0 +1,294 @@
+; SPDX-License-Identifier: GPL-3.0-or-later
+	val-override-date: "20200722144207"
+	trust-anchor: ". IN DS 20326 8 2 E06D44B80B8F1D39A95C0B0D7C65D08458E880409BBC683457104237C7F8EC8D"
+CONFIG_END
+
+SCENARIO_BEGIN Forwarding: forwarder sent RRSIGs with invalid signed for an insecure zone, it should not cause SERVFAIL because the zone is insecure
+
+
+; forwarder
+RANGE_BEGIN 0 100
+	ADDRESS 8.8.8.8
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id
+REPLY QR RD RA AD CD NOERROR
+SECTION QUESTION
+. IN DNSKEY
+SECTION ANSWER
+. 86913 IN DNSKEY 256 3 8 AwEAAdauOGxLhfAKFTTZwGhBXbk793QK dWIQRjiSftWdusCwkPhNyJrIjwtNffCW XGLlZAbpcs414RE3oS1qVwV+AdXsO92S Bu5haGlxMUk0NqZO7Xlf84/wrzGZVRRo uPo5pNX/CKS8Mv9UOi0olKGCu31dNfh8 qCszWZcloLDgeLzSnQSkvFoGe69vNCfh 7feESKedkBC2qRz0BZv9+oJI0IY/3D7W EnV0NOlf8gSHozhfJFJ/ZAKtvw/Q3ogr VJFk0LyVaU/NVtVA5FM4pVMIRID7pfrP i78aAzG7b/Wh/Pce4jPAIpS3dApq25Yk vMuPvfB91NMf9FemKwlp78PBVcM=
+. 86913 IN DNSKEY 257 3 8 AwEAAaz/tAm8yTn4Mfeh5eyI96WSVexT BAvkMgJzkKTOiW1vkIbzxeF3+/4RgWOq 7HrxRixHlFlExOLAJr5emLvN7SWXgnLh 4+B5xQlNVz8Og8kvArMtNROxVQuCaSnI DdD5LKyWbRd2n9WGe2R8PzgCmr3EgVLr jyBxWezF0jLHwVN8efS3rCj/EWgvIWgb 9tarpVUDK/b58Da+sqqls3eNbuv7pr+e oZG+SrDK6nWeL3c6H5Apxz7LjVc1uTId sIXxuOLYA4/ilBmSVIzuDWfdRUfhHdY6 +cn8HFRm+2hM8AnXGXws9555KrUB5qih ylGa8subX2Nn6UwNR1AkUTV74bU=
+. 86913 IN RRSIG DNSKEY 8 0 172800 20200811000000 20200721000000 20326 . IcMH/yNRoNKkCPmOo8MDcMEZO4sF8p0A 8xgASRnD1c0t+VSU5NRzh05eME7RJrRP 31T/E4eUh+jyI18Gz/O5Lg02Zu1wmcOy Mnkr+bfU+Al7pCztj+6aGTUl34HFyWtM cChKkeJQDeJoBtyVDVa4oL1FQs4Ml6HC OOjzoOKIHakrfCLyaktN82G+uNFXt0CB SGR2xQSWDKnzqSJqCep9X8NtNjjAFus2 g8weAXomG2+gRlrNfQAFqcGPjLHeVtZv yco3u0u8ZOp+8PC8fnlLhtpJ3DBXgwFp wY3V7uM7Zfabcio64st79wu4zNwZR5uf IEpKciMtUh8J8LfVWFM62w==
+ENTRY_END
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id
+REPLY QR RD RA AD CD NXDOMAIN
+SECTION QUESTION
+_TA-4f66. IN NULL
+SECTION AUTHORITY
+. 86161 IN NSEC aaa. NS SOA RRSIG NSEC DNSKEY
+. 86161 IN RRSIG NSEC 8 0 86400 20200804050000 20200722040000 46594 . zNoDySatAPoT5YV6XmQcz3qs60+GxuEo yITrzrWMEU1keQNU+6663BM6N/F6G2nd b5Bj5cY5m7MN7iZnBFN/cXQd7EWjdLTC Fw7FxBPc3J51vqShIaM2xxpm9RRdpaB/ vfei+x2e+4YRCJJdw81qmrUBBohANyNW 119JAEufoTgAVY9jPd8699lJ4svMY10E avFAL+PTfC/la9KKNPlOgDgbVRjpUZcU wLeooyqggterm4kXcnWahk3PtG3tmB7A zz1qccY6rOeQALloUQ3Im1Wl9s6pbExZ XI/6qBXYetdexB6DpebnsAk1P4wTprhQ iIxvZpHCppz/jMAx/KDRjQ==
+. 86161 IN RRSIG SOA 8 0 86400 20200804050000 20200722040000 46594 . qI98OcNtjSzHbTbiNg6MZRopwcTAW0Cm JiHKdcEOzGY+Tabxyl76YDeVWEZuKrYG pzeqFLKC05W+4nQrUKTmCoI89YHFNdAc f8uO7zbSEM6dFlS4ksCZFkZZHb2hjp4g KI1MEkI56EsojYqEDa1fXakpytEucvKO 2qJgcqPVkb29lk2lePIicO4YIddI38M4 BNdKsCnEhdMYC76lKls7EYMfJeHAr+FX c3SZIAG/r3ov2KR0u/CNqDDlKcfsGCVt wRCWE/EYUMuZbCNW7/cZ8fCWps1Xn7fu I8N7YLgMTqAsAmXx4I86zf8TAUTslgYN 5IR69n16/l2h6QP9vJPS3g==
+. 86161 IN SOA a.root-servers.net. nstld.verisign-grs.com. 2020072200 1800 900 604800 86400
+ENTRY_END
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id
+REPLY QR RD RA AD CD NOERROR
+SECTION QUESTION
+fi. IN DS
+SECTION ANSWER
+fi. 48962 IN DS 44855 8 2 80cd184a31c50d5dc44b4f98811f298315986b44edcc0666455c6aef7dbd997e
+fi. 48962 IN RRSIG DS 8 1 86400 20200803200000 20200721190000 46594 . HhKwynZK3BYIdOYlwFp6wLacu8uci+ig va3NggxT/LdJqCXlIpuBV5EBGFnEowA9 dYJMdJkkbizYmqkTLbAqaomS5nH3Juz4 5rvjtqi2/viyZjy9VfIPtWx5T5+xfSHH tLac4rJk8ieKSxhpjcc9tITGFT0cnU7U kpWD8OO/0toJF94diLleqS7M/uCDIYyj zgvwIuvx0WxwgxG6bG45EvwfWQbIMRTi R2XSzKtOTRSBbXtI0XKoGrTblOkVxCei uQka3Jqpm/HvmFa9rsspylXTC/6VkKwC u+/TogoJ9vobAr9vXpLx0LiYTkh3GKzZ QL0uw/36jcqplPHlddICPg==
+ENTRY_END
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id
+REPLY QR RD RA AD CD NOERROR
+SECTION QUESTION
+fi. IN DNSKEY
+SECTION ANSWER
+fi. 793 IN DNSKEY 256 3 8 AwEAAbfXUBTwb2oWNVvv3kCwgaER6vZ6 76rm5DsLmQjOuClDEHXRtH4JmX+nbjmX yFfeNRBasI0jr2sLIYSPB2TF7ctF/FLB a4zgEKIOTiwM2Q58bBxzUhXtU2KAgqEo V5X7kHYau899uJSW+CUJhKAPYpb/sb41 VqSUrsxkACf5ocZ4k4K57H81B2OKZSHC u6C6h4h7D59l8fwYg7F+RAr2vJENfbSM EjHfIWt54x7WfDuCKGDYvpoKmdgg/ACg 6CyLMttbml5dCZ9XJyWyFbs7eJZYGOgN Uw/3ezxmouChVSqqOeVzZAwfsUAsjb1l 1GSSj3YSiRVY4FWewrdw7XL09v0=
+fi. 793 IN DNSKEY 257 3 8 AwEAAb9AMR4NV2YxZH9E6ELMFY5DOszk dTd5AxhSg1YZWi8B9cruHXjghFCmApd1 VfUyQ4MX3DZbskfML/ToxumeSv9OhfA4 I6Fao9bN9UxsBbFlkqwqhAGmuJapSgNu yMWArSoUG4XB/dykPNdyFt+3t1dEH/S3 hS5JmZccSI6YAjnUfG+Pd45R8ljO8ERI 1wSa0IJjDArkuFaLcGrtjR9GJluVmM15 0gWVUIiUkBfDUz8pFjqAWewk0QY9TX22 Z8gfl3yKhO9TYPVHN1oMHTydVqjQKbdb s/BvGXx/GPh63OOxE2ICmxXcz2Ma+082 eA0DfwKLo86PFOre8YK7pEWuw4U=
+fi. 793 IN RRSIG DNSKEY 8 1 900 20200805163544 20200722030600 44855 fi. p9isNtIsiD4yhCQkiVeyfPva4iXV8+oE hhU/SEec2ykGjs22yiscFKppV/4s738y Tl58F682IXAq5jolf/6ShAMOUqxzMD1j 5nphLZ62O5B/r6Ah9JiJf9l748mXHCAW kOnwep4IpkEJkiS1lOHgcxd0hw/rsRNZ QAAgiDhYBGcTIWLw6FFsWL/sMJTEnMim 4QzkDLrF4MlFRduQSffC2N7mBbtQpwYt BFS38tZHQZ7w48or3GGJw7ejwR7IQQQJ VYO7yWr13eLZiGPnne51tvltO7LVeDbl cskxbGWYdtTaB+klcukrVlApqUopqjbT mgzA60/IMKe4PXk+QnzZeA==
+ENTRY_END
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id
+REPLY QR RD RA CD NOERROR
+SECTION QUESTION
+dIGiTrAnSIT.FI. IN DS
+SECTION AUTHORITY
+FI. 1334 IN SOA a.FI. fi-domain-tech.ficora.FI. 2020072239 3605 1800 2419200 86400
+FI. 21134 IN RRSIG SOA 8 1 86400 20200805082122 20200722074635 20436 fi. mXyNMPJRTLMLOKDjZ2ET/z1SOO9g0a8o o1dsHchts2X0uPvYu6Hc8quBCmUbmjhe qu9dRDiDtjCyddFScwn9FTI9CRMJKytB 1LVcrlBrbuWFlmDilRLkhrK2gmm6MOYU /VGgj+kgEtIQE7NSGF35NQHTJfDw1Jmo FxGAo7I//QBAHJemx5Q4YmbVMDiyTBjz FCLSdAjCGouJTRU9jFgweoEivGk+yD+H vsaaG7NTumzK4miU3SL4sMPb9NYr+HIR 2j+6pUjD05x9UOKAfIQzFnRcToDB1KUo ZZr8teWnLH3fbHCq9JGfz338Eju0wdfe 0E2CGL6Cc77+VThotyTrAg==
+es7p5jquq6ng6hd9vn5q3el38s2vuoqh.FI. 21134 IN NSEC3 1 1 5 7298d6895c6c0415 escp8o5mqifge1u5itme7ju27k5hf19a NS DS RRSIG
+es7p5jquq6ng6hd9vn5q3el38s2vuoqh.FI. 21134 IN RRSIG NSEC3 8 2 86400 20200805124944 20200722030600 20436 fi. S/DGd4jI4zndv50oMGp2BmB/aH9/M3AX /My9hwZ4zi2r88DrYiNyd2ghyuUvZO9a lvY2NcB9cX9sjAdQAM/xmoHsoraB5YWV v53YBTJDF+kY7BzO5mqImNWmkpe/Kcxt Mpp9Gz02ySpPp37dot4FbdK9A0RWERVw XkoEaFvLkHRf3QGMJUBnCjKJ7r448axs OAKdHIIQb6aG6OATML6mJx6xHOeI8CFl giTrgixGOR/qGP92i9ErcP9iQ2lvHlfK A7SuOLi6uSPBYWIgZzkqGJOpJ0o+cPHV 69QX/SP7m0qr00shV+rxfyppHCLUpKBx iXacRghILlVV5mUgV/25lw==
+ml0llbvj7rbbtgbp31q2j3d3qv89643r.FI. 21134 IN NSEC3 1 1 5 7298d6895c6c0415 ml0mjk4qs3b070682obd52l1p9v07cl6 NS SOA TXT RRSIG DNSKEY NSEC3PARAM
+ml0llbvj7rbbtgbp31q2j3d3qv89643r.FI. 21134 IN RRSIG NSEC3 8 2 86400 20200804210456 20200722030600 20436 fi. bLLvaTmn2WXk8RxKz7Kb28FoDSgNuIoj ZPrpnwyYVRltfYvOe8wOtzzPQtDYj9F8 bqZgPmZFIAQfsKJk86NMsEWvArGYhX8z 1w6z4qkfpgXpLGeV6fNjLMi/YHZRHQJn cELLNcxh/U9e+xuURCr55XzgzpVVnXpk fm2848LbLO/9p2ZltOGd+GWcyQxxt/aK FlSHUHz2Zp27/9wNCxRyQ8EKtR4eIic8 T9p4kgu5w6302GPSAlfbFCX8Yf+ikMvE Fy7XdbLiE+Uyt0PjEnayT51kqxL2DJFe vtY6Y+MSKazC5xBJudtB6S3owmCDd4PL OhOtxu8lwuuU/FVLteZwvg==
+ENTRY_END
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id
+REPLY QR RD RA CD NOERROR
+SECTION QUESTION
+diGITrANsiT.fI. IN NS
+SECTION ANSWER
+diGITrANsiT.fI. 3134 IN NS dns1.ficora.fI.
+diGITrANsiT.fI. 3134 IN NS dns2.ficora.fI.
+diGITrANsiT.fI. 3134 IN NS ns-secondary.funet.fI.
+diGITrANsiT.fI. 3134 IN NS ns1.z.fI.
+diGITrANsiT.fI. 3134 IN NS ns2.z.fI.
+; following RRSIG signer is out-of-bailiwick, i.e. nonsense
+diGITrANsiT.fI. 3134 IN RRSIG NS 10 2 3600 20190517083644 20190117083646 28100 droneinfo.fi. XFNrVGseG3exPEFC58o3tgRckNghA9+G Psc8w8lUgJW7NGPuWHM4aSuhgMWL3nxk kCqTYI60RerzNV1PNxFLlfyBzuwi6rqe dOjpud7Nr9giKQc2r2YsOSLrSfcRN4Wq KGllqTVXZAYIbF5+QYA+2x3sY1StATQS mb2qqYPPB6iR/EPuHOn/1DA9gzJKXdQS wWwRWSuzBtO89q/e/zhSlCsWhk96POR7 du1KpJb58wPdNm6+Jznwj7E7KphZaTID mexL5S9Sf6VwDNDHkSOGT9x182tjIXTs kZcpFZgJTDgrR+vwVwjXmvAs/CKQmMax D0ZuRbMjvgvaMkCsBRjtDQ==
+ENTRY_END
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id
+REPLY QR RD RA CD NOERROR
+SECTION QUESTION
+Api.dIGiTRaNsit.Fi. IN A
+SECTION ANSWER
+Api.dIGiTRaNsit.Fi. 3357 IN CNAME digitransit-prod.trafficmanager.net.
+digitransit-aks.westeurope.cloudapp.azure.com. 9 IN A 40.119.148.209
+digitransit-prod.trafficmanager.net. 299 IN CNAME digitransit-aks.westeurope.cloudapp.azure.com.
+ENTRY_END
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id
+REPLY QR RD RA AD CD NOERROR
+SECTION QUESTION
+nET. IN DS
+SECTION ANSWER
+nET. 56393 IN DS 35886 8 2 7862b27f5f516ebe19680444d4ce5e762981931842c465f00236401d8bd973ee
+nET. 56393 IN RRSIG DS 8 1 86400 20200803200000 20200721190000 46594 . PtZ4PuUSHtwvVksquoCtgL5ylNkYaBJk uXVY0Xx4FOyJ8U5kJwlQzScXS8/W7/4m NMLRJWvDIfEMTwpRtFpgd71THg5w3M+O He4GoQ5dGaaSuREvpYCHY+O6aeO/t3DX P3mTcps+CJlIOJckiRirvv3V1u7jmTGB t4jZ6Gn27CX9lPXGUkhWrDx9EOW1p7ky ZYtFGtkVxGmqnMqoNMSz+JaFmN43uaJU grJt6B8aKFIw3MR1Z4xCX3oYzd5jDdQt sS1h8frflyyN/dF/aIl5BW58sc8qkgGS kv8iUgHW1/E24chcMQFngnOuAAF6hjaA K4SJCdrCXUNiduL8H9Q5MQ==
+ENTRY_END
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id
+REPLY QR RD RA AD CD NOERROR
+SECTION QUESTION
+nEt. IN DNSKEY
+SECTION ANSWER
+nEt. 21146 IN DNSKEY 256 3 8 AQPeYYme8NvhAl+0XjyGqHVep4Y1T2Or RmO+L3QGULBlOe571PnxI+gRyXCQmtN7 WpoJxzALFSVBPsggqwOP+wnmCx8DZ49N HrfS7WbMtoYHTtiaIvHTjZZ88leuCtNL qfIH8N1Ax68Xnf4uKobYFgZXj0M2Zi7Y I84iFkCpIyZk6VIiJpvpNgyCK5mWetPF 2zmO2jXC8M045JIPam38reXD
+nEt. 21146 IN DNSKEY 257 3 8 AQOYBnzqWXIEj6mlgXg4LWC0HP2n8eK8 XqgHlmJ/69iuIHsa1TrHDG6TcOra/pye GKwH0nKZhTmXSuUFGh9BCNiwVDuyyb6O BGy2Nte9Kr8NwWg4q+zhSoOf4D+gC9dE zg0yFdwT0DKEvmNPt0K4jbQDS4Yimb+u PKuF6yieWWrPYYCrv8C9KC8JMze2uT6N uWBfsl2fDUoV4l65qMww06D7n+p7Rbdw WkAZ0fA63mXVXBZF6kpDtsYD7SUB9jhh fLQE/r85bvg3FaSs5Wi2BaqN06SzGWI1 DHu7axthIOeHwg00zxlhTpoYCH0ldoQz +S65zWYi/fRJiyLSBb6JZOvn
+nEt. 21146 IN RRSIG DNSKEY 8 1 86400 20200728162830 20200713162330 35886 net. BsxHqTUrVNqYdQdv5uriiUd/p+Dh5F12 /01oniA3F1keMZU1V+pbELcih+1gfLs3 i+f88p/9r3kM8gghxQtInzyJl3lPdeBM 7LjWuonQR5CzvfnM4WAgkVZZxmFB7l6b bj+ey9mwocAMR1ht9502MgB4eQLOHVve 3mdCXYuilxwQ9vOrVsFDLiELVoCDVtQi csatJy3Z/LU31IWtR8c6Ta/ItApgqsWg fU8Br3uyHesiDbA2FSfBb9qWFfGcNrDJ ZGF9dLCxvMeHSU5AKpEwX8flOKWKRVwM nB/+LB1owMmcyao82yJlL7y7vxfrQDb0 V0uJaQMEiQl7XGBsT+8Hgg==
+ENTRY_END
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id
+REPLY QR RD RA CD NOERROR
+SECTION QUESTION
+TRAFficManaGer.NEt. IN DS
+SECTION AUTHORITY
+A1RT98BS5QGC9NFI51S9HCI47ULJG6JH.NEt. 21540 IN NSEC3 1 1 0 - a1ruuffjkct2q54p78f8ejgj8jbk7i8b NS SOA RRSIG DNSKEY NSEC3PARAM
+A1RT98BS5QGC9NFI51S9HCI47ULJG6JH.NEt. 21540 IN RRSIG NSEC3 8 2 86400 20200728064417 20200721053417 56519 net. B4N1ZLUcMCAkfgGNrmJfXylkUAbPnqxO 31ZQ5ZwU0AecyChOkGGTelH/87eM7RtG M7mqrM6zU9CnGwsgheqg2HCbpX7n5Fvl 1AclnJZBuFlF0hvejSO99rrLrLRaTWQt LyJwVQJWkMfgztCO5Mh2ngJfK6ZB1PLS xOFqVz0j5MTYYp9QwdL1PvLIaBAw0kTg cm3o476wB0glMo6yzDbK2A==
+CS431SS8CTI7M6JHMN592GRLI9T17OK7.NEt. 21540 IN NSEC3 1 1 0 - cs49egn3atpo6m7fblhased3j00k92nb NS DS RRSIG
+CS431SS8CTI7M6JHMN592GRLI9T17OK7.NEt. 21540 IN RRSIG NSEC3 8 2 86400 20200727063544 20200720052544 56519 net. FB73aPYNlR3FqN1gmxYeIccL+ybiv+8A ymQkJDevhRITdI76YqbobqbvAKQg9Knm lSe5OtWZEmI6h+qbYXtXfnAGl+GayzbL LsSyUABJdWp8ZuGooatayzGqjWUpIGZr qgAZIK+twkCKUicgi2XhCztnVr1wVf2z L0tRuctiZQRdoDlcRfFzXBsg21Kn3eVy ivjnZUzp93vL1ZrBhhZfMg==
+NEt. 840 IN RRSIG SOA 8 1 900 20200729095953 20200722084953 56519 net. GEY1baT1zShB6uxFAyHlg6EPfEbCxp3E 3C2l8OeVCBwgzBdP9TwDeXH+//RcfT9w Q++Wan2q/0W5I9fJRWZKGDPkdmhOcvh9 VjJRlb3DwZdJEeDc3Rj3dip3MvL7OyZt 8lfv42/WoBYHXeduQwGknz0KbNpeSqU0 BjV4C9O/w5rUSjvk3z6Qka7jz3/0sz7H 4FfXqv5CxkUCKYyl9PzxuA==
+NEt. 840 IN SOA a.gtld-servers.NEt. nstld.verisign-grs.com. 1595411993 1800 900 604800 86400
+ENTRY_END
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id
+REPLY QR RD RA CD NOERROR
+SECTION QUESTION
+TrAfFicMANAger.net. IN NS
+SECTION ANSWER
+TrAfFicMANAger.net. 21041 IN NS tm1.dns-tm.com.
+TrAfFicMANAger.net. 21041 IN NS tm1.edgedns-tm.info.
+TrAfFicMANAger.net. 21041 IN NS tm2.dns-tm.com.
+TrAfFicMANAger.net. 21041 IN NS tm2.edgedns-tm.info.
+ENTRY_END
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id
+REPLY QR RD RA CD NOERROR
+SECTION QUESTION
+Api.dIGiTRaNsit.Fi. IN A
+SECTION ANSWER
+Api.dIGiTRaNsit.Fi. 3585 IN CNAME digitransit-prod.trafficmanager.net.
+digitransit-aks.westeurope.cloudapp.azure.com. 9 IN A 40.119.148.209
+digitransit-prod.trafficmanager.net. 285 IN CNAME digitransit-aks.westeurope.cloudapp.azure.com.
+ENTRY_END
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id
+REPLY QR RD RA CD NOERROR
+SECTION QUESTION
+DigiTranSiT-pROd.tRaffiCmanAgeR.Net. IN A
+SECTION ANSWER
+DigiTranSiT-pROd.tRaffiCmanAgeR.Net. 299 IN CNAME digitransit-aks.westeurope.cloudapp.azure.com.
+digitransit-aks.westeurope.cloudapp.azure.com. 9 IN A 40.119.148.209
+ENTRY_END
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id
+REPLY QR RD RA CD NOERROR
+SECTION QUESTION
+DigiTranSiT-pROd.tRaffiCmanAgeR.Net. IN A
+SECTION ANSWER
+DigiTranSiT-pROd.tRaffiCmanAgeR.Net. 299 IN CNAME digitransit-aks.westeurope.cloudapp.azure.com.
+digitransit-aks.westeurope.cloudapp.azure.com. 9 IN A 40.119.148.209
+ENTRY_END
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id
+REPLY QR RD RA AD CD NOERROR
+SECTION QUESTION
+coM. IN DS
+SECTION ANSWER
+coM. 86251 IN DS 30909 8 2 e2d3c916f6deeac73294e8268fb5885044a833fc5459588f4a9184cfc41a5766
+coM. 86251 IN RRSIG DS 8 1 86400 20200803200000 20200721190000 46594 . F3sngBM8xYQ10Z3iIVWUqlMFLvecizXH 2d5kM4iguQL088Cv6xz1Ep3d4wUVEzlL YBBrsCQB627WztctcVPFiXUn22cWwzky 7yxjII8YY72V2x2/758hmZMCSHdSzJph By9Wv5Av5O8qqLt1QyYq8r6cZK7352Vk ICENa/OhKWX3dUvQ+EQe+3JUN5q/Xfeb WnCiuG2LgaWIgl/f+yjpMEkg808EUCCz 41Dbe81gwIadN+vvpjvpb3j5cBfozwqk thyCWlXt2+ZUUH4aSr5q5WsS8nD4gb70 6YC+A08woNmeYms8t40irruVMdlUzrXC Fz7+azz0zCEAc046A9v5fQ==
+ENTRY_END
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id
+REPLY QR RD RA AD CD NOERROR
+SECTION QUESTION
+coM. IN DNSKEY
+SECTION ANSWER
+coM. 20944 IN DNSKEY 256 3 8 AwEAAdVECVAFFKnwlH7lDYpsSvv50Z7E JP518luWdiN7X5igYJo6dLij/noOhYO0 ppmTghphtSqHn75/qMmETK9NiUfLW4M9 X8j/IvIr1xrTPEb6+dipDE9xKjhMGFUu fOeXHiBoMQiKLNzlssYuz90oQrEwCKpa 5R4cYYFiZaoeezi2NQeIAY82dh/8auvF zqCOewWx/J2zVh8YHqfkGeXyzsM=
+coM. 20944 IN DNSKEY 257 3 8 AQPDzldNmMvZFX4NcNJ0uEnKDg7tmv/F 3MyQR0lpBmVcNcsIszxNFxsBfKNW9JYC Yqpik8366LE7VbIcNRzfp2h9OO8HRl+H +E08zauK8k7evWEmu/6od+2boggPoiEf GNyvNPaSI7FOIroDsnw/taggzHRX1Z7S OiOiPWPNIwSUyWOZ79VmcQ1GLkC6NlYv G3HwYmynQv6oFwGv/KELSw7ZSdrbTQ0H XvZbqMUI7BaMskmvgm1G7oKZ1YiF7O9i oVNc0+7ASbqmZN7Z98EGU/Qh2K/BgUe8 Hs0XVcdPKrtyYnoQHd2ynKPcMMlTEih2 /2HDHjRPJ2aywIpKNnv4oPo/
+coM. 20944 IN RRSIG DNSKEY 8 1 86400 20200729182421 20200714181921 30909 com. kWt6r1qzHb1LABToPGz61aVgRBHMIkS+ x1FbuHxh+Ha9nYtlnl1AOju4CjMC6gje qBXYhhwpZWC4VFSE+hVXuI2NNEPvtcD1 Om9eu69KEK8d1rXmho+PBzJyzXSSUpM6 KtapTL0NDdjg+uCt6YmWNli/e3QdRAoI u5eNnmFBK5viaGcnIP5l8/QdXH+dBmfi qrrs+z0oJv89euCCjH0UeMfVJUetHTox MLiB4GlMyQnPWsNXNZPzQEWk8CeLEhVu e8QVvMQmq+GfcvRF/jFnTsL9ILTMYiJR 8gYp5YnFtBgtrqPoekmAaJ0dig2bXFVV /x8RzR/wFd8yUHTaT+AWkA==
+ENTRY_END
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id
+REPLY QR RD RA CD NOERROR
+SECTION QUESTION
+AZURe.com. IN DS
+SECTION AUTHORITY
+2VPE4QITM4PLV486G56AB7OUDVIO1U3D.com. 21574 IN NSEC3 1 1 0 - 2vpf134m9p90k8k9jmtdjemi4anqnsaf NS DS RRSIG
+2VPE4QITM4PLV486G56AB7OUDVIO1U3D.com. 21574 IN RRSIG NSEC3 8 2 86400 20200726043358 20200719032358 24966 com. SpLKFkZ534rLzf6WTHf+JdBCanfiUhX1 BbmjpFQRI+l1qRN9po9mtA95jfw8AGjw S0n36LK9MBNF4pRo4zcmxny3/K7lfDwf 6HhDlNMp3KQGtLMGcSCqw7StxA3b3qsg 0NhxPtHl818RsBKueIR88LPX88x5jkzC Gr11WJoVlq682pCJlmkVOze2JCmRvjYY m/mUHv4y5+mh3h2AbHc+zA==
+CK0POJMG874LJREF7EFN8430QVIT8BSM.com. 21574 IN NSEC3 1 1 0 - ck0q1gin43n1arrc9osm6qpqr81h5m9a NS SOA RRSIG DNSKEY NSEC3PARAM
+CK0POJMG874LJREF7EFN8430QVIT8BSM.com. 21574 IN RRSIG NSEC3 8 2 86400 20200728044213 20200721033213 24966 com. qoAss2VVxsBWG9+MAQ3giAmCnzf4dz7G ppZsQfkt3b7cFIVgO3TiWPWkusb3BEbp sma2Q+x/TBLeeHYm6l1HWXMIl7zcYLsA XY0ZzoWaqNPTPH6YNDAreZYP21UekBL7 g710cndRk4oaJUNz5t8sGi3JaOJF046Q cUz6gGg7NLMvyGlJWzmftGbxgp9ovdOg wmirddESGOj33kuCfSJvWA==
+com. 874 IN RRSIG SOA 8 1 900 20200729100807 20200722085807 24966 com. kDvHo8x7ut5Lu66MSUOUTPvxfYJLXMcu aKPCu9I+jTYZOzAH4KquPm+765a/gnp5 2okPhEUJTO2JYumhfkjyG04kE4HCnqfR bWtjjfIyqXo34km+CR8rG8RGZ6QilLWZ 0yxux5+izvuji4L4KLeTxPwUJQFgAmVA 59unj2IqysGWRc2ETSofHOPFrydduuyc DJdQLN6Dq1fMFh849Qr6nw==
+com. 874 IN SOA a.gtld-servers.net. nstld.verisign-grs.com. 1595412487 1800 900 604800 86400
+ENTRY_END
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id
+REPLY QR RD RA CD NOERROR
+SECTION QUESTION
+AZURe.COM. IN NS
+SECTION ANSWER
+AZURe.COM. 21462 IN NS ns1-205.azure-dns.COM.
+AZURe.COM. 21462 IN NS ns2-205.azure-dns.net.
+AZURe.COM. 21462 IN NS ns3-205.azure-dns.org.
+AZURe.COM. 21462 IN NS ns4-205.azure-dns.info.
+ENTRY_END
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id
+REPLY QR RD RA CD NOERROR
+SECTION QUESTION
+DigitRaNsit-aKS.WESTEuROPe.CloUDApp.aZuRe.cOm. IN A
+SECTION ANSWER
+DigitRaNsit-aKS.WESTEuROPe.CloUDApp.aZuRe.cOm. 9 IN A 40.119.148.209
+ENTRY_END
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id
+REPLY QR RD RA NOERROR
+SECTION QUESTION
+api.digitransit.fi. IN A
+SECTION ANSWER
+api.digitransit.fi. 3357 IN CNAME digitransit-prod.trafficmanager.net.
+digitransit-aks.westeurope.cloudapp.azure.com. 9 IN A 40.119.148.209
+digitransit-prod.trafficmanager.net. 299 IN CNAME digitransit-aks.westeurope.cloudapp.azure.com.
+ENTRY_END
+
+ENTRY_BEGIN
+MATCH qname  qtype
+ADJUST copy_id
+REPLY QR RD RA CD NOERROR
+SECTION QUESTION
+DigitRaNsit-aKS.WESTEuROPe.CloUDApp.aZuRe.cOm. IN A
+SECTION ANSWER
+DigitRaNsit-aKS.WESTEuROPe.CloUDApp.aZuRe.cOm. 9 IN A 40.119.148.209
+ENTRY_END
+
+RANGE_END
+
+
+STEP 10 QUERY
+ENTRY_BEGIN
+REPLY RD
+SECTION QUESTION
+api.digitransit.fi.	IN A
+ENTRY_END
+
+STEP 11 CHECK_ANSWER
+ENTRY_BEGIN
+MATCH all
+REPLY QR RD RA NOERROR
+SECTION QUESTION
+api.digitransit.fi.	IN A
+SECTION ANSWER
+api.digitransit.fi.	IN CNAME	digitransit-prod.trafficmanager.net.
+digitransit-prod.trafficmanager.net.	IN CNAME	digitransit-aks.westeurope.cloudapp.azure.com.
+digitransit-aks.westeurope.cloudapp.azure.com.	IN A	40.119.148.209
+ENTRY_END
+
+SCENARIO_END
diff --git a/lib/layer/validate.test.integr/kresd_config.j2 b/lib/layer/validate.test.integr/kresd_config.j2
new file mode 100644
index 0000000..ba6767f
--- /dev/null
+++ b/lib/layer/validate.test.integr/kresd_config.j2
@@ -0,0 +1,52 @@
+-- SPDX-License-Identifier: GPL-3.0-or-later
+
+trust_anchors.remove('.')
+{% for TAF in TRUST_ANCHOR_FILES %}
+trust_anchors.add_file('{{TAF}}')
+{% endfor %}
+
+{% raw %}
+-- Disable RFC5011 TA update
+if ta_update then
+        modules.unload('ta_update')
+end
+
+-- Disable RFC8145 signaling, scenario doesn't provide expected answers
+if ta_signal_query then
+        modules.unload('ta_signal_query')
+end
+
+-- Disable RFC8109 priming, scenario doesn't provide expected answers
+if priming then
+        modules.unload('priming')
+end
+
+-- Disable this module because it make one priming query
+if detect_time_skew then
+        modules.unload('detect_time_skew')
+end
+
+cache.size = 2*MB
+verbose(true)
+policy.add(policy.all(policy.DEBUG_ALWAYS))
+policy.add(policy.all(policy.FORWARD('8.8.8.8')))
+{% endraw %}
+
+net = { '{{SELF_ADDR}}' }
+
+-- Self-checks on globals
+assert(help() ~= nil)
+assert(worker.id ~= nil)
+-- Self-checks on facilities
+assert(cache.count() == 0)
+assert(cache.stats() ~= nil)
+assert(cache.backends() ~= nil)
+assert(worker.stats() ~= nil)
+assert(net.interfaces() ~= nil)
+-- Self-checks on loaded stuff
+assert(net.list()[1].transport.ip == '{{SELF_ADDR}}')
+assert(#modules.list() > 0)
+-- Self-check timers
+ev = event.recurrent(1 * sec, function (ev) return 1 end)
+event.cancel(ev)
+ev = event.after(0, function (ev) return 1 end)
diff --git a/lib/meson.build b/lib/meson.build
new file mode 100644
index 0000000..d24d997
--- /dev/null
+++ b/lib/meson.build
@@ -0,0 +1,122 @@
+# libkres
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+libkres_src = files([
+  'cache/api.c',
+  'cache/cdb_lmdb.c',
+  'cache/entry_list.c',
+  'cache/entry_pkt.c',
+  'cache/entry_rr.c',
+  'cache/knot_pkt.c',
+  'cache/nsec1.c',
+  'cache/nsec3.c',
+  'cache/peek.c',
+  'dnssec.c',
+  'dnssec/nsec.c',
+  'dnssec/nsec3.c',
+  'dnssec/signature.c',
+  'dnssec/ta.c',
+  'generic/lru.c',
+  'generic/map.c',
+  'generic/queue.c',
+  'generic/trie.c',
+  'layer/cache.c',
+  'layer/iterate.c',
+  'layer/validate.c',
+  'module.c',
+  'resolve.c',
+  'rplan.c',
+  'selection.c',
+  'selection_forward.c',
+  'selection_iter.c',
+  'utils.c',
+  'zonecut.c',
+])
+c_src_lint += libkres_src
+
+libkres_headers = files([
+  'cache/api.h',
+  'cache/cdb_api.h',
+  'cache/cdb_lmdb.h',
+  'cache/impl.h',
+  'defines.h',
+  'dnssec.h',
+  'dnssec/nsec.h',
+  'dnssec/nsec3.h',
+  'dnssec/signature.h',
+  'dnssec/ta.h',
+  'generic/array.h',
+  'generic/lru.h',
+  'generic/map.h',
+  'generic/pack.h',
+  'generic/queue.h',
+  'generic/trie.h',
+  'layer.h',
+  'layer/iterate.h',
+  'module.h',
+  'resolve.h',
+  'rplan.h',
+  'selection.h',
+  'selection_forward.h',
+  'selection_iter.h',
+  'utils.h',
+  'zonecut.h',
+])
+
+unit_tests += [
+  ['array', files('generic/test_array.c')],
+  ['lru', files('generic/test_lru.c')],
+  ['map', files('generic/test_map.c')],
+  ['pack', files('generic/test_pack.c')],
+  ['queue', files('generic/test_queue.c')],
+  ['set', files('generic/test_set.c')],
+  ['trie', files('generic/test_trie.c')],
+  ['module', files('test_module.c')],
+  ['rplan', files('test_rplan.c')],
+  ['utils', files('test_utils.c')],
+  ['zonecut', files('test_zonecut.c')],
+]
+
+integr_tests += [
+  ['cache_overflow', meson.current_source_dir() / 'cache' / 'overflow.test.integr'],
+  ['cache_minimal_nsec', meson.current_source_dir() / 'cache' / 'test.integr'],
+  ['iter_limits' , meson.current_source_dir() / 'layer' / 'test.integr'],
+  ['validate' , meson.current_source_dir() / 'layer' / 'validate.test.integr'],
+]
+
+libkres_inc = include_directories('..')
+
+libkres_lib = library('kres',
+  libkres_src,
+  soversion: libkres_soversion,
+  include_directories: libkres_inc,
+  dependencies: [
+    contrib_dep,
+    kresconfig_dep,
+    libuv,
+    lmdb,
+    libknot,
+    libdnssec,
+    gnutls,
+    luajit,
+  ],
+  install: true,
+)
+
+libkres_dep = declare_dependency(
+  include_directories: libkres_inc,
+  link_with: libkres_lib
+)
+
+install_headers(
+  libkres_headers,
+  subdir: 'libkres',
+)
+
+pkgconfig = import('pkgconfig')
+pkgconfig.generate(
+  name: 'libkres',
+  description: 'Knot Resolver library',
+  url: 'https://knot-resolver.cz/',
+  libraries: [libkres_lib],
+)
diff --git a/lib/module.c b/lib/module.c
new file mode 100644
index 0000000..2174f90
--- /dev/null
+++ b/lib/module.c
@@ -0,0 +1,147 @@
+/*  Copyright (C) 2015-2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#include <stdlib.h>
+#include <dlfcn.h>
+#include <contrib/cleanup.h>
+
+#include "kresconfig.h"
+#include "lib/defines.h"
+#include "lib/utils.h"
+#include "lib/module.h"
+
+
+/* List of embedded modules.  These aren't (un)loaded. */
+int iterate_init(struct kr_module *self);
+int validate_init(struct kr_module *self);
+int cache_init(struct kr_module *self);
+kr_module_init_cb kr_module_get_embedded(const char *name)
+{
+	if (strcmp(name, "iterate") == 0)
+		return iterate_init;
+	if (strcmp(name, "validate") == 0)
+		return validate_init;
+	if (strcmp(name, "cache") == 0)
+		return cache_init;
+	return NULL;
+}
+
+/** Load prefixed symbol. */
+static void *load_symbol(void *lib, const char *prefix, const char *name)
+{
+	auto_free char *symbol = kr_strcatdup(2, prefix, name);
+	return dlsym(lib, symbol);
+}
+
+static int load_library(struct kr_module *module, const char *name, const char *path)
+{
+	assert(module && name && path);
+	/* Absolute or relative path (then only library search path is used). */
+	auto_free char *lib_path = kr_strcatdup(4, path, "/", name, LIBEXT);
+	if (lib_path == NULL) {
+		return kr_error(ENOMEM);
+	}
+
+	/* Workaround for buggy _fini/__attribute__((destructor)) and dlclose(),
+	 * this keeps the library mapped until the program finishes though. */
+	module->lib = dlopen(lib_path, RTLD_NOW | RTLD_NODELETE);
+	if (module->lib) {
+		return kr_ok();
+	}
+
+	return kr_error(ENOENT);
+}
+
+/** Load C module symbols. */
+static int load_sym_c(struct kr_module *module, uint32_t api_required)
+{
+	module->init = kr_module_get_embedded(module->name);
+	if (module->init) {
+		return kr_ok();
+	}
+	#pragma GCC diagnostic push
+	#pragma GCC diagnostic ignored "-Wpedantic" /* casts after load_symbol() */
+	/* Check if it's embedded first */
+	/* Load dynamic library module */
+	auto_free char *m_prefix = kr_strcatdup(2, module->name, "_");
+
+	/* Check ABI version, return error on mismatch. */
+	module_api_cb *api = load_symbol(module->lib, m_prefix, "api");
+	if (api == NULL) {
+		return kr_error(ENOENT);
+	}
+	if (api() != api_required) {
+		return kr_error(ENOTSUP);
+	}
+
+	/* Load ABI by symbol names. */
+	#define ML(symname) module->symname = \
+		load_symbol(module->lib, m_prefix, #symname)
+	ML(init);
+	ML(deinit);
+	ML(config);
+	#undef ML
+	if (load_symbol(module->lib, m_prefix, "layer")
+	    || load_symbol(module->lib, m_prefix, "props")) {
+		/* In case someone re-compiled against new kresd
+		 * but haven't actually changed the symbols. */
+		kr_log_error("[system] module %s requires upgrade.  Please refer to "
+			"https://knot-resolver.readthedocs.io/en/stable/upgrading.html",
+			module->name);
+		return kr_error(ENOTSUP);
+	}
+
+	return kr_ok();
+	#pragma GCC diagnostic pop
+}
+
+int kr_module_load(struct kr_module *module, const char *name, const char *path)
+{
+	if (module == NULL || name == NULL) {
+		return kr_error(EINVAL);
+	}
+
+	/* Initialize, keep userdata */
+	void *data = module->data;
+	memset(module, 0, sizeof(struct kr_module));
+	module->data = data;
+	module->name = strdup(name);
+	if (module->name == NULL) {
+		return kr_error(ENOMEM);
+	}
+
+	/* Search for module library. */
+	if (!path || load_library(module, name, path) != 0) {
+		module->lib = RTLD_DEFAULT;
+	}
+
+	/* Try to load module ABI. */
+	int ret = load_sym_c(module, KR_MODULE_API);
+	if (ret == 0 && module->init) {
+		ret = module->init(module);
+	}
+	if (ret != 0) {
+		kr_module_unload(module);
+	}
+
+	return ret;
+}
+
+void kr_module_unload(struct kr_module *module)
+{
+	if (module == NULL) {
+		return;
+	}
+
+	if (module->deinit) {
+		module->deinit(module);
+	}
+
+	if (module->lib && module->lib != RTLD_DEFAULT) {
+		dlclose(module->lib);
+	}
+
+	free(module->name);
+	memset(module, 0, sizeof(struct kr_module));
+}
diff --git a/lib/module.h b/lib/module.h
new file mode 100644
index 0000000..011acbb
--- /dev/null
+++ b/lib/module.h
@@ -0,0 +1,112 @@
+/*  Copyright (C) 2015-2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+/** @file
+ * Module API definition and functions for (un)loading modules.
+ */
+
+#pragma once
+
+#include "lib/defines.h"
+#include "lib/utils.h"
+#include "lib/layer.h"
+
+struct kr_module;
+struct kr_prop;
+
+
+/**
+ * Export module API version (place this at the end of your module).
+ *
+ * @param module module name (e.g. policy)
+ */
+#define KR_MODULE_EXPORT(module) \
+    KR_EXPORT uint32_t module ## _api() { return KR_MODULE_API; }
+#define KR_MODULE_API ((uint32_t) 0x20210125)
+
+typedef uint32_t (module_api_cb)(void);
+
+
+/**
+ * Module representation.
+ *
+ * The five symbols (init, ...) may be defined by the module as name_init(), etc;
+ * all are optional and missing symbols are represented as NULLs;
+ */
+struct kr_module {
+	char *name;
+
+	/** Constructor.  Called after loading the module.  @return error code.
+	 * Lua modules: not populated, called via lua directly. */
+	int (*init)(struct kr_module *self);
+
+	/** Destructor.  Called before unloading the module.  @return error code. */
+	int (*deinit)(struct kr_module *self);
+
+	/** Configure with encoded JSON (NULL if missing).  @return error code.
+	 * Lua modules: not used and not useful from C.
+	 * When called from lua, input is JSON, like for kr_prop_cb. */
+	int (*config)(struct kr_module *self, const char *input);
+
+	/** Packet processing API specs.  May be NULL.  See docs on that type.
+	 * Owned by the module code. */
+	const kr_layer_api_t *layer;
+
+	/** List of properties.  May be NULL.  Terminated by { NULL, NULL, NULL }.
+	 * Lua modules: not used and not useful. */
+	const struct kr_prop *props;
+
+	/** dlopen() handle; RTLD_DEFAULT for embedded modules; NULL for lua modules. */
+	void *lib;
+	void *data; /**< Custom data context. */
+};
+
+/**
+ * Module property callback.  Input and output is passed via a JSON encoded in a string.
+ *
+ * @param env pointer to the lua engine, i.e. struct engine *env (TODO: explicit type)
+ * @param input parameter (NULL if missing/nil on lua level)
+ * @return a free-form JSON output (malloc-ated)
+ * @note see modules_create_table_for_c() implementation for details
+ *       about the input/output conversion.
+ */
+typedef char *(kr_prop_cb)(void *env, struct kr_module *self, const char *input);
+
+/**
+ * Module property (named callable).
+ */
+struct kr_prop {
+	kr_prop_cb *cb;
+	const char *name;
+	const char *info;
+};
+
+
+/**
+ * Load a C module instance into memory.  And call its init().
+ *
+ * @param module module structure.  Will be overwritten except for ->data on success.
+ * @param name module name
+ * @param path module search path
+ * @return 0 or an error
+ */
+KR_EXPORT
+int kr_module_load(struct kr_module *module, const char *name, const char *path);
+
+/**
+ * Unload module instance.
+ *
+ * @param module module structure
+ * @note currently used even for lua modules
+ */
+KR_EXPORT
+void kr_module_unload(struct kr_module *module);
+
+typedef int (*kr_module_init_cb)(struct kr_module *);
+/**
+ * Get embedded module's init function by name (or NULL).
+ */
+KR_EXPORT
+kr_module_init_cb kr_module_get_embedded(const char *name);
+
diff --git a/lib/resolve.c b/lib/resolve.c
new file mode 100644
index 0000000..8bfd690
--- /dev/null
+++ b/lib/resolve.c
@@ -0,0 +1,1609 @@
+/*  Copyright (C) 2014-2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#include <ctype.h>
+#include <inttypes.h>
+#include <stdio.h>
+#include <fcntl.h>
+#include <assert.h>
+#include <arpa/inet.h>
+#include <libknot/rrtype/rdname.h>
+#include <libknot/descriptor.h>
+#include <ucw/mempool.h>
+#include <sys/socket.h>
+#include "kresconfig.h"
+#include "lib/resolve.h"
+#include "lib/layer.h"
+#include "lib/rplan.h"
+#include "lib/layer/iterate.h"
+#include "lib/dnssec/ta.h"
+#include "lib/dnssec.h"
+#if ENABLE_COOKIES
+#include "lib/cookies/control.h"
+#include "lib/cookies/helper.h"
+#include "lib/cookies/nonce.h"
+#else /* Define compatibility macros */
+#define KNOT_EDNS_OPTION_COOKIE 10
+#endif /* ENABLE_COOKIES */
+
+#define VERBOSE_MSG(qry, ...) QRVERBOSE((qry), "resl",  __VA_ARGS__)
+
+bool kr_rank_check(uint8_t rank)
+{
+	switch (rank & ~KR_RANK_AUTH) {
+	case KR_RANK_INITIAL:
+	case KR_RANK_OMIT:
+	case KR_RANK_TRY:
+	case KR_RANK_INDET:
+	case KR_RANK_BOGUS:
+	case KR_RANK_MISMATCH:
+	case KR_RANK_MISSING:
+	case KR_RANK_INSECURE:
+	case KR_RANK_SECURE:
+		return true;
+	default:
+		return false;
+	}
+}
+
+bool kr_rank_test(uint8_t rank, uint8_t kr_flag)
+{
+	assert(kr_rank_check(rank) && kr_rank_check(kr_flag));
+	if (kr_flag == KR_RANK_AUTH) {
+		return rank & KR_RANK_AUTH;
+	}
+	assert(!(kr_flag & KR_RANK_AUTH));
+	/* The rest are exclusive values - exactly one has to be set. */
+	return (rank & ~KR_RANK_AUTH) == kr_flag;
+}
+
+/** @internal Set @a yielded to all RRs with matching @a qry_uid. */
+static void set_yield(ranked_rr_array_t *array, const uint32_t qry_uid, const bool yielded)
+{
+	for (unsigned i = 0; i < array->len; ++i) {
+		ranked_rr_array_entry_t *entry = array->at[i];
+		if (entry->qry_uid == qry_uid) {
+			entry->yielded = yielded;
+		}
+	}
+}
+
+/**
+ * @internal Defer execution of current query.
+ * The current layer state and input will be pushed to a stack and resumed on next iteration.
+ */
+static int consume_yield(kr_layer_t *ctx, knot_pkt_t *pkt)
+{
+	struct kr_request *req = ctx->req;
+	size_t pkt_size = pkt->size;
+	if (knot_pkt_has_tsig(pkt)) {
+		pkt_size += pkt->tsig_wire.len;
+	}
+	knot_pkt_t *pkt_copy = knot_pkt_new(NULL, pkt_size, &req->pool);
+	struct kr_layer_pickle *pickle = mm_alloc(&req->pool, sizeof(*pickle));
+	if (pickle && pkt_copy && knot_pkt_copy(pkt_copy, pkt) == 0) {
+		struct kr_query *qry = req->current_query;
+		pickle->api = ctx->api;
+		pickle->state = ctx->state;
+		pickle->pkt = pkt_copy;
+		pickle->next = qry->deferred;
+		qry->deferred = pickle;
+		set_yield(&req->answ_selected, qry->uid, true);
+		set_yield(&req->auth_selected, qry->uid, true);
+		return kr_ok();
+	}
+	return kr_error(ENOMEM);
+}
+static int begin_yield(kr_layer_t *ctx) { return kr_ok(); }
+static int reset_yield(kr_layer_t *ctx) { return kr_ok(); }
+static int finish_yield(kr_layer_t *ctx) { return kr_ok(); }
+static int produce_yield(kr_layer_t *ctx, knot_pkt_t *pkt) { return kr_ok(); }
+static int checkout_yield(kr_layer_t *ctx, knot_pkt_t *packet, struct sockaddr *dst, int type) { return kr_ok(); }
+static int answer_finalize_yield(kr_layer_t *ctx) { return kr_ok(); }
+
+/** @internal Macro for iterating module layers. */
+#define RESUME_LAYERS(from, r, qry, func, ...) \
+    (r)->current_query = (qry); \
+	for (size_t i = (from); i < (r)->ctx->modules->len; ++i) { \
+		struct kr_module *mod = (r)->ctx->modules->at[i]; \
+		if (mod->layer) { \
+			struct kr_layer layer = {.state = (r)->state, .api = mod->layer, .req = (r)}; \
+			if (layer.api && layer.api->func) { \
+				(r)->state = layer.api->func(&layer, ##__VA_ARGS__); \
+				/* It's an easy mistake to return error code, for example. */ \
+				/* (though we could allow such an overload later) */ \
+				if (unlikely(!kr_state_consistent((r)->state))) { \
+					assert(!EINVAL); \
+					(r)->state = KR_STATE_FAIL; \
+				} else \
+				if ((r)->state == KR_STATE_YIELD) { \
+					func ## _yield(&layer, ##__VA_ARGS__); \
+					break; \
+				} \
+			} \
+		} \
+	} /* Invalidate current query. */ \
+	(r)->current_query = NULL
+
+/** @internal Macro for starting module iteration. */
+#define ITERATE_LAYERS(req, qry, func, ...) RESUME_LAYERS(0, req, qry, func, ##__VA_ARGS__)
+
+/** @internal Find layer id matching API. */
+static inline size_t layer_id(struct kr_request *req, const struct kr_layer_api *api) {
+	module_array_t *modules = req->ctx->modules;
+	for (size_t i = 0; i < modules->len; ++i) {
+		if (modules->at[i]->layer == api) {
+			return i;
+		}
+	}
+	return 0; /* Not found, try all. */
+}
+
+/* @internal We don't need to deal with locale here */
+KR_CONST static inline bool isletter(unsigned chr)
+{ return (chr | 0x20 /* tolower */) - 'a' <= 'z' - 'a'; }
+
+/* Randomize QNAME letter case.
+ * This adds 32 bits of randomness at maximum, but that's more than an average domain name length.
+ * https://tools.ietf.org/html/draft-vixie-dnsext-dns0x20-00
+ */
+static void randomized_qname_case(knot_dname_t * restrict qname, uint32_t secret)
+{
+	if (secret == 0) {
+		return;
+	}
+	assert(qname);
+	const int len = knot_dname_size(qname) - 2; /* Skip first, last label. First is length, last is always root */
+	for (int i = 0; i < len; ++i) {
+		/* Note: this relies on the fact that correct label lengths
+		 * can't pass the isletter() test (by "luck"). */
+		if (isletter(*++qname)) {
+				*qname ^= ((secret >> (i & 31)) & 1) * 0x20;
+		}
+	}
+}
+
+/** This turns of QNAME minimisation if there is a non-terminal between current zone cut, and name target.
+ *  It save several minimization steps, as the zone cut is likely final one.
+ */
+static void check_empty_nonterms(struct kr_query *qry, knot_pkt_t *pkt, struct kr_cache *cache, uint32_t timestamp)
+{
+	// FIXME cleanup, etc.
+#if 0
+	if (qry->flags.NO_MINIMIZE) {
+		return;
+	}
+
+	const knot_dname_t *target = qry->sname;
+	const knot_dname_t *cut_name = qry->zone_cut.name;
+	if (!target || !cut_name)
+		return;
+
+	struct kr_cache_entry *entry = NULL;
+	/* @note: The non-terminal must be direct child of zone cut (e.g. label distance <= 2),
+	 *        otherwise this would risk leaking information to parent if the NODATA TTD > zone cut TTD. */
+	int labels = knot_dname_labels(target, NULL) - knot_dname_labels(cut_name, NULL);
+	while (target[0] && labels > 2) {
+		target = knot_wire_next_label(target, NULL);
+		--labels;
+	}
+	for (int i = 0; i < labels; ++i) {
+		int ret = kr_cache_peek(cache, KR_CACHE_PKT, target, KNOT_RRTYPE_NS, &entry, &timestamp);
+		if (ret == 0) { /* Either NXDOMAIN or NODATA, start here. */
+			/* @todo We could stop resolution here for NXDOMAIN, but we can't because of broken CDNs */
+			qry->flags.NO_MINIMIZE = true;
+			kr_make_query(qry, pkt);
+			break;
+		}
+		assert(target[0]);
+		target = knot_wire_next_label(target, NULL);
+	}
+	kr_cache_commit(cache);
+#endif
+}
+
+static int ns_fetch_cut(struct kr_query *qry, const knot_dname_t *requested_name,
+			struct kr_request *req, knot_pkt_t *pkt)
+{
+	/* It can occur that here parent query already have
+	 * provably insecured zonecut which not in the cache yet. */
+	struct kr_qflags pflags;
+	if (qry->parent) {
+		pflags = qry->parent->flags;
+	}
+	const bool is_insecured = qry->parent != NULL
+		&& !(pflags.AWAIT_IPV4 || pflags.AWAIT_IPV6)
+		&& (pflags.DNSSEC_INSECURE || pflags.DNSSEC_NODS);
+
+	/* Want DNSSEC if it's possible to secure this name
+	 * (e.g. is covered by any TA) */
+	if (is_insecured) {
+		/* If parent is unsecured we don't want DNSSEC
+		 * even if cut name is covered by TA. */
+		qry->flags.DNSSEC_WANT = false;
+		qry->flags.DNSSEC_INSECURE = true;
+		VERBOSE_MSG(qry, "=> going insecure because parent query is insecure\n");
+	} else if (kr_ta_covers_qry(req->ctx, qry->zone_cut.name, KNOT_RRTYPE_NS)) {
+		qry->flags.DNSSEC_WANT = true;
+	} else {
+		qry->flags.DNSSEC_WANT = false;
+		VERBOSE_MSG(qry, "=> going insecure because there's no covering TA\n");
+	}
+
+	struct kr_zonecut cut_found;
+	kr_zonecut_init(&cut_found, requested_name, req->rplan.pool);
+	/* Cut that has been found can differs from cut that has been requested.
+	 * So if not already insecured,
+	 * try to fetch ta & keys even if initial cut name not covered by TA */
+	bool secured = !is_insecured;
+	int ret = kr_zonecut_find_cached(req->ctx, &cut_found, requested_name,
+					 qry, &secured);
+	if (ret == kr_error(ENOENT)) {
+		/* No cached cut found, start from SBELT
+		 * and issue priming query. */
+		kr_zonecut_deinit(&cut_found);
+		ret = kr_zonecut_set_sbelt(req->ctx, &qry->zone_cut);
+		if (ret != 0) {
+			return KR_STATE_FAIL;
+		}
+		VERBOSE_MSG(qry, "=> using root hints\n");
+		qry->flags.AWAIT_CUT = false;
+		return KR_STATE_DONE;
+	} else if (ret != kr_ok()) {
+		kr_zonecut_deinit(&cut_found);
+		return KR_STATE_FAIL;
+	}
+
+	/* Find out security status.
+	 * Go insecure if the zone cut is provably insecure */
+	if ((qry->flags.DNSSEC_WANT) && !secured) {
+		VERBOSE_MSG(qry, "=> NS is provably without DS, going insecure\n");
+		qry->flags.DNSSEC_WANT = false;
+		qry->flags.DNSSEC_INSECURE = true;
+	}
+	/* Zonecut name can change, check it again
+	 * to prevent unnecessary DS & DNSKEY queries */
+	if (!(qry->flags.DNSSEC_INSECURE) &&
+	    kr_ta_covers_qry(req->ctx, cut_found.name, KNOT_RRTYPE_NS)) {
+		qry->flags.DNSSEC_WANT = true;
+	} else {
+		qry->flags.DNSSEC_WANT = false;
+	}
+	/* Check if any DNSKEY found for cached cut */
+	if (qry->flags.DNSSEC_WANT && cut_found.key == NULL &&
+	    kr_zonecut_is_empty(&cut_found)) {
+		/* Cut found and there are no proofs of zone insecurity.
+		 * But no DNSKEY found and no glue fetched.
+		 * We have got circular dependency - must fetch A\AAAA
+		 * from authoritative, but we have no key to verify it. */
+		kr_zonecut_deinit(&cut_found);
+		if (requested_name[0] != '\0' ) {
+			/* If not root - try next label */
+			return KR_STATE_CONSUME;
+		}
+		/* No cached cut & keys found, start from SBELT */
+		ret = kr_zonecut_set_sbelt(req->ctx, &qry->zone_cut);
+		if (ret != 0) {
+			return KR_STATE_FAIL;
+		}
+		VERBOSE_MSG(qry, "=> using root hints\n");
+		qry->flags.AWAIT_CUT = false;
+		return KR_STATE_DONE;
+	}
+	/* Use the found zone cut. */
+	kr_zonecut_move(&qry->zone_cut, &cut_found);
+	/* Check if there's a non-terminal between target and current cut. */
+	struct kr_cache *cache = &req->ctx->cache;
+	check_empty_nonterms(qry, pkt, cache, qry->timestamp.tv_sec);
+	/* Cut found */
+	return KR_STATE_PRODUCE;
+}
+
+static int edns_put(knot_pkt_t *pkt, bool reclaim)
+{
+	if (!pkt->opt_rr) {
+		return kr_ok();
+	}
+	if (reclaim) {
+		/* Reclaim reserved size. */
+		int ret = knot_pkt_reclaim(pkt, knot_edns_wire_size(pkt->opt_rr));
+		if (ret != 0) {
+			return ret;
+		}
+	}
+	/* Write to packet. */
+	assert(pkt->current == KNOT_ADDITIONAL);
+	return knot_pkt_put(pkt, KNOT_COMPR_HINT_NONE, pkt->opt_rr, KNOT_PF_FREE);
+}
+
+/** Removes last EDNS OPT RR written to the packet. */
+static int edns_erase_and_reserve(knot_pkt_t *pkt)
+{
+	/* Nothing to be done. */
+	if (!pkt || !pkt->opt_rr) {
+		return 0;
+	}
+
+	/* Fail if the data are located elsewhere than at the end of packet. */
+	if (pkt->current != KNOT_ADDITIONAL ||
+	    pkt->opt_rr != &pkt->rr[pkt->rrset_count - 1]) {
+		return -1;
+	}
+
+	size_t len = knot_rrset_size(pkt->opt_rr);
+	int16_t rr_removed = pkt->opt_rr->rrs.count;
+	/* Decrease rrset counters. */
+	pkt->rrset_count -= 1;
+	pkt->sections[pkt->current].count -= 1;
+	pkt->size -= len;
+	knot_wire_add_arcount(pkt->wire, -rr_removed); /* ADDITIONAL */
+
+	pkt->opt_rr = NULL;
+
+	/* Reserve the freed space. */
+	return knot_pkt_reserve(pkt, len);
+}
+
+static int edns_create(knot_pkt_t *pkt, const struct kr_request *req)
+{
+	pkt->opt_rr = knot_rrset_copy(req->ctx->upstream_opt_rr, &pkt->mm);
+	size_t wire_size = knot_edns_wire_size(pkt->opt_rr);
+#if ENABLE_COOKIES
+	if (req->ctx->cookie_ctx.clnt.enabled ||
+	    req->ctx->cookie_ctx.srvr.enabled) {
+		wire_size += KR_COOKIE_OPT_MAX_LEN;
+	}
+#endif /* ENABLE_COOKIES */
+	if (req->qsource.flags.tls) {
+		if (req->ctx->tls_padding == -1)
+			/* FIXME: we do not know how to reserve space for the
+			 * default padding policy, since we can't predict what
+			 * it will select. So i'm just guessing :/ */
+			wire_size += KNOT_EDNS_OPTION_HDRLEN + 512;
+		if (req->ctx->tls_padding >= 2)
+			wire_size += KNOT_EDNS_OPTION_HDRLEN + req->ctx->tls_padding;
+	}
+	return knot_pkt_reserve(pkt, wire_size);
+}
+
+/**
+ * @param all_secure optionally &&-combine security of written RRs into its value.
+ *		     (i.e. if you pass a pointer to false, it will always remain)
+ * @param all_cname optionally output if all written RRs are CNAMEs and RRSIGs of CNAMEs
+ * @return error code, ignoring if forced to truncate the packet.
+ */
+static int write_extra_ranked_records(const ranked_rr_array_t *arr, uint16_t reorder,
+				      knot_pkt_t *answer, bool *all_secure, bool *all_cname)
+{
+	const bool has_dnssec = knot_pkt_has_dnssec(answer);
+	bool all_sec = true;
+	bool all_cn = (all_cname != NULL); /* optim.: init as false if not needed */
+	int err = kr_ok();
+
+	for (size_t i = 0; i < arr->len; ++i) {
+		ranked_rr_array_entry_t * entry = arr->at[i];
+		assert(!entry->in_progress);
+		if (!entry->to_wire) {
+			continue;
+		}
+		knot_rrset_t *rr = entry->rr;
+		if (!has_dnssec) {
+			if (rr->type != knot_pkt_qtype(answer) && knot_rrtype_is_dnssec(rr->type)) {
+				continue;
+			}
+		}
+		err = knot_pkt_put_rotate(answer, 0, rr, reorder, 0);
+		if (err != KNOT_EOK) {
+			if (err == KNOT_ESPACE) {
+				err = kr_ok();
+			}
+			break;
+		}
+
+		if (rr->type != KNOT_RRTYPE_RRSIG) {
+			all_sec = all_sec && kr_rank_test(entry->rank, KR_RANK_SECURE);
+		}
+		all_cn = all_cn && kr_rrset_type_maysig(entry->rr) == KNOT_RRTYPE_CNAME;
+	}
+
+	if (all_secure) {
+		*all_secure = *all_secure && all_sec;
+	}
+	if (all_cname) {
+		*all_cname = all_cn;
+	}
+	return err;
+}
+
+/** @internal Add an EDNS padding RR into the answer if requested and required. */
+static int answer_padding(struct kr_request *request)
+{
+	if (!request || !request->answer || !request->ctx) {
+		assert(false);
+		return kr_error(EINVAL);
+	}
+	if (!request->qsource.flags.tls) {
+		/* Not meaningful to pad without encryption. */
+		return kr_ok();
+	}
+	int32_t padding = request->ctx->tls_padding;
+	knot_pkt_t *answer = request->answer;
+	knot_rrset_t *opt_rr = answer->opt_rr;
+	int32_t pad_bytes = -1;
+
+	if (padding == -1) { /* use the default padding policy from libknot */
+		pad_bytes =  knot_pkt_default_padding_size(answer, opt_rr);
+	}
+	if (padding >= 2) {
+		int32_t max_pad_bytes = knot_edns_get_payload(opt_rr) - (answer->size + knot_rrset_size(opt_rr));
+		pad_bytes = MIN(knot_edns_alignment_size(answer->size, knot_rrset_size(opt_rr), padding),
+				max_pad_bytes);
+	}
+
+	if (pad_bytes >= 0) {
+		uint8_t zeros[MAX(1, pad_bytes)];
+		memset(zeros, 0, sizeof(zeros));
+		int r = knot_edns_add_option(opt_rr, KNOT_EDNS_OPTION_PADDING,
+					     pad_bytes, zeros, &answer->mm);
+		if (r != KNOT_EOK) {
+			knot_rrset_clear(opt_rr, &answer->mm);
+			return kr_error(r);
+		}
+	}
+	return kr_ok();
+}
+
+/* Make a clean SERVFAIL answer. */
+static void answer_fail(struct kr_request *request)
+{
+	/* Note: OPT in SERVFAIL response is still useful for cookies/additional info. */
+	if (VERBOSE_STATUS || kr_log_rtrace_enabled(request))
+		kr_log_req(request, 0, 0, "resl",
+			"request failed, answering with empty SERVFAIL\n");
+	knot_pkt_t *answer = request->answer;
+	knot_rrset_t *opt_rr = answer->opt_rr; /* it gets NULLed below */
+	int ret = kr_pkt_clear_payload(answer);
+	knot_wire_clear_ad(answer->wire);
+	knot_wire_clear_aa(answer->wire);
+	knot_wire_set_rcode(answer->wire, KNOT_RCODE_SERVFAIL);
+	if (ret == 0 && opt_rr) {
+		knot_pkt_begin(answer, KNOT_ADDITIONAL);
+		answer->opt_rr = opt_rr;
+		answer_padding(request); /* Ignore failed padding in SERVFAIL answer. */
+		edns_put(answer, false);
+	}
+}
+
+/* Append EDNS records into the answer. */
+static int answer_append_edns(struct kr_request *request)
+{
+	knot_pkt_t *answer = request->answer;
+	if (!answer->opt_rr)
+		return kr_ok();
+	int ret = answer_padding(request);
+	if (!ret) ret = knot_pkt_begin(answer, KNOT_ADDITIONAL);
+	if (!ret) ret = knot_pkt_put(answer, KNOT_COMPR_HINT_NONE,
+				     answer->opt_rr, KNOT_PF_FREE);
+	return ret;
+}
+
+static void answer_finalize(struct kr_request *request)
+{
+	struct kr_rplan *rplan = &request->rplan;
+	knot_pkt_t *answer = request->answer;
+	const uint8_t *q_wire = request->qsource.packet->wire;
+
+	if (answer->rrset_count != 0) {
+		/* Non-standard: we assume the answer had been constructed.
+		 * Let's check we don't have a "collision". */
+		const ranked_rr_array_t *selected[] = kr_request_selected(request);
+		for (int psec = KNOT_ANSWER; psec <= KNOT_ADDITIONAL; ++psec) {
+			const ranked_rr_array_t *arr = selected[psec];
+			for (ssize_t i = 0; i < arr->len; ++i) {
+				if (unlikely(arr->at[i]->to_wire)) {
+					assert(false);
+					answer_fail(request);
+					return;
+				}
+			}
+		}
+		/* We only add EDNS, and we even assume AD bit was correct. */
+		if (answer_append_edns(request)) {
+			answer_fail(request);
+			return;
+		}
+		return;
+	}
+
+	struct kr_query *const last =
+		rplan->resolved.len > 0 ? array_tail(rplan->resolved) : NULL;
+		/* TODO  ^^^^ this is slightly fragile */
+
+	if (!last) {
+		/* Suspicious: no kr_query got resolved (not even from cache),
+		 * so let's (defensively) SERVFAIL the request.
+		 * ATM many checks below depend on `last` anyway,
+		 * so this helps to avoid surprises. */
+		answer_fail(request);
+		return;
+	}
+	/* TODO: clean this up in !660 or followup, and it isn't foolproof anyway. */
+	if (last->flags.DNSSEC_BOGUS
+	    || (rplan->pending.len > 0 && array_tail(rplan->pending)->flags.DNSSEC_BOGUS)) {
+		if (!knot_wire_get_cd(q_wire)) {
+			answer_fail(request);
+			return;
+		}
+	}
+
+	/* AD flag.  We can only change `secure` from true to false.
+	 * Be conservative.  Primary approach: check ranks of all RRs in wire.
+	 * Only "negative answers" need special handling. */
+	bool secure = last != NULL && request->state == KR_STATE_DONE /*< suspicious otherwise */
+		&& knot_pkt_qtype(answer) != KNOT_RRTYPE_RRSIG;
+	if (last && (last->flags.STUB)) {
+		secure = false; /* don't trust forwarding for now */
+	}
+	if (last && (last->flags.DNSSEC_OPTOUT)) {
+		VERBOSE_MSG(last, "insecure because of opt-out\n");
+		secure = false; /* the last answer is insecure due to opt-out */
+	}
+
+	/* Write all RRsets meant for the answer. */
+	const uint16_t reorder = last ? last->reorder : 0;
+	bool answ_all_cnames = false/*arbitrary*/;
+	if (knot_pkt_begin(answer, KNOT_ANSWER)
+	    || write_extra_ranked_records(&request->answ_selected, reorder,
+					answer, &secure, &answ_all_cnames)
+	    || knot_pkt_begin(answer, KNOT_AUTHORITY)
+	    || write_extra_ranked_records(&request->auth_selected, reorder,
+					answer, &secure, NULL)
+	    || knot_pkt_begin(answer, KNOT_ADDITIONAL)
+	    || write_extra_ranked_records(&request->add_selected, reorder,
+					answer, NULL/*not relevant to AD*/, NULL)
+	    || answer_append_edns(request)
+	   )
+	{
+		answer_fail(request);
+		return;
+	}
+
+	if (!last) secure = false; /*< should be no-op, mostly documentation */
+	/* AD: "negative answers" need more handling. */
+	if (kr_response_classify(answer) != PKT_NOERROR
+	    /* Additionally check for CNAME chains that "end in NODATA",
+	     * as those would also be PKT_NOERROR. */
+	    || (answ_all_cnames && knot_pkt_qtype(answer) != KNOT_RRTYPE_CNAME)) {
+
+		secure = secure && last->flags.DNSSEC_WANT
+			&& !last->flags.DNSSEC_BOGUS && !last->flags.DNSSEC_INSECURE;
+	}
+
+	if (secure) {
+		struct kr_query *cname_parent = last->cname_parent;
+		while (cname_parent != NULL) {
+			if (cname_parent->flags.DNSSEC_OPTOUT) {
+				secure = false;
+				break;
+			}
+			cname_parent = cname_parent->cname_parent;
+		}
+	}
+
+	/* No detailed analysis ATM, just _SECURE or not.
+	 * LATER: request->rank might better be computed in validator's finish phase. */
+	VERBOSE_MSG(last, "AD: request%s classified as SECURE\n", secure ? "" : " NOT");
+	request->rank = secure ? KR_RANK_SECURE : KR_RANK_INITIAL;
+
+	/* Set AD if secure and AD bit "was requested". */
+	if (secure && !knot_wire_get_cd(q_wire)
+	    && (knot_pkt_has_dnssec(answer) || knot_wire_get_ad(q_wire))) {
+		knot_wire_set_ad(answer->wire);
+	}
+}
+
+static int query_finalize(struct kr_request *request, struct kr_query *qry, knot_pkt_t *pkt)
+{
+	knot_pkt_begin(pkt, KNOT_ADDITIONAL);
+	if (qry->flags.NO_EDNS)
+		return kr_ok();
+	/* Remove any EDNS records from any previous iteration. */
+	int ret = edns_erase_and_reserve(pkt);
+	if (ret) return ret;
+	ret = edns_create(pkt, request);
+	if (ret) return ret;
+	if (qry->flags.STUB) {
+		/* Stub resolution (ask for +rd and +do) */
+		knot_wire_set_rd(pkt->wire);
+		if (knot_pkt_has_dnssec(request->qsource.packet)) {
+			knot_edns_set_do(pkt->opt_rr);
+		}
+		if (knot_wire_get_cd(request->qsource.packet->wire)) {
+			knot_wire_set_cd(pkt->wire);
+		}
+	} else {
+		/* Full resolution (ask for +cd and +do) */
+		knot_edns_set_do(pkt->opt_rr);
+		knot_wire_set_cd(pkt->wire);
+		if (qry->flags.FORWARD) {
+			knot_wire_set_rd(pkt->wire);
+		}
+	}
+	return kr_ok();
+}
+
+int kr_resolve_begin(struct kr_request *request, struct kr_context *ctx)
+{
+	/* Initialize request */
+	request->ctx = ctx;
+	request->answer = NULL;
+	request->options = ctx->options;
+	request->state = KR_STATE_CONSUME;
+	request->current_query = NULL;
+	array_init(request->answ_selected);
+	array_init(request->auth_selected);
+	array_init(request->add_selected);
+	request->answ_validated = false;
+	request->auth_validated = false;
+	request->rank = KR_RANK_INITIAL;
+	request->trace_log = NULL;
+	request->trace_finish = NULL;
+
+	/* Expect first query */
+	kr_rplan_init(&request->rplan, request, &request->pool);
+	return KR_STATE_CONSUME;
+}
+
+static int resolve_query(struct kr_request *request, const knot_pkt_t *packet)
+{
+	struct kr_rplan *rplan = &request->rplan;
+	const knot_dname_t *qname = knot_pkt_qname(packet);
+	uint16_t qclass = knot_pkt_qclass(packet);
+	uint16_t qtype = knot_pkt_qtype(packet);
+	struct kr_query *qry = NULL;
+	struct kr_context *ctx = request->ctx;
+	struct kr_cookie_ctx *cookie_ctx = ctx ? &ctx->cookie_ctx : NULL;
+
+	if (qname != NULL) {
+		qry = kr_rplan_push(rplan, NULL, qname, qclass, qtype);
+	} else if (cookie_ctx && cookie_ctx->srvr.enabled &&
+		   knot_wire_get_qdcount(packet->wire) == 0 &&
+		   knot_pkt_has_edns(packet) &&
+		   knot_pkt_edns_option(packet, KNOT_EDNS_OPTION_COOKIE)) {
+		/* Plan empty query only for cookies. */
+		qry = kr_rplan_push_empty(rplan, NULL);
+	}
+	if (!qry) {
+		return KR_STATE_FAIL;
+	}
+
+	if (qname != NULL) {
+		/* Deferred zone cut lookup for this query. */
+		qry->flags.AWAIT_CUT = true;
+		/* Want DNSSEC if it's posible to secure this name (e.g. is covered by any TA) */
+		if ((knot_wire_get_ad(packet->wire) || knot_pkt_has_dnssec(packet)) &&
+		    kr_ta_covers_qry(request->ctx, qry->sname, qtype)) {
+			qry->flags.DNSSEC_WANT = true;
+		}
+	}
+
+	/* Expect answer, pop if satisfied immediately */
+	ITERATE_LAYERS(request, qry, begin);
+	if ((request->state & KR_STATE_DONE) != 0) {
+		kr_rplan_pop(rplan, qry);
+	} else if (qname == NULL) {
+		/* it is an empty query which must be resolved by
+		   `begin` layer of cookie module.
+		   If query isn't resolved, fail. */
+		request->state = KR_STATE_FAIL;
+	}
+	return request->state;
+}
+
+knot_pkt_t *kr_request_ensure_answer(struct kr_request *request)
+{
+	if (request->answer)
+		return request->answer;
+
+	const knot_pkt_t *qs_pkt = request->qsource.packet;
+	assert(qs_pkt);
+	// Find answer_max: limit on DNS wire length.
+	uint16_t answer_max;
+	const struct kr_request_qsource_flags *qs_flags = &request->qsource.flags;
+	assert((qs_flags->tls || qs_flags->http) ? qs_flags->tcp : true);
+	if (!request->qsource.addr || qs_flags->tcp) {
+		// not on UDP
+		answer_max = KNOT_WIRE_MAX_PKTSIZE;
+	} else if (knot_pkt_has_edns(qs_pkt)) {
+		// UDP with EDNS
+		answer_max = MIN(knot_edns_get_payload(qs_pkt->opt_rr),
+				 knot_edns_get_payload(request->ctx->downstream_opt_rr));
+		answer_max = MAX(answer_max, KNOT_WIRE_MIN_PKTSIZE);
+	} else {
+		// UDP without EDNS
+		answer_max = KNOT_WIRE_MIN_PKTSIZE;
+	}
+
+	// Allocate the packet.
+	uint8_t *wire = NULL;
+	if (request->alloc_wire_cb) {
+		wire = request->alloc_wire_cb(request, &answer_max);
+		if (!wire)
+			goto enomem;
+	}
+	knot_pkt_t *answer = request->answer =
+		knot_pkt_new(wire, answer_max, &request->pool);
+	if (!answer || knot_pkt_init_response(answer, qs_pkt) != 0) {
+		assert(!answer); // otherwise we messed something up
+		goto enomem;
+	}
+	if (!wire)
+		wire = answer->wire;
+
+	// Much was done by knot_pkt_init_response()
+	knot_wire_set_ra(wire);
+	knot_wire_set_rcode(wire, KNOT_RCODE_NOERROR);
+	if (knot_wire_get_cd(qs_pkt->wire)) {
+		knot_wire_set_cd(wire);
+	}
+
+	// Prepare EDNS if required.
+	if (knot_pkt_has_edns(qs_pkt)) {
+		answer->opt_rr = knot_rrset_copy(request->ctx->downstream_opt_rr,
+						 &answer->mm);
+		if (!answer->opt_rr)
+			goto enomem; // answer is on mempool, so "leak" is OK
+		if (knot_pkt_has_dnssec(qs_pkt))
+			knot_edns_set_do(answer->opt_rr);
+	}
+
+	return request->answer;
+enomem:
+	request->state = KR_STATE_FAIL; // TODO: really combine with another flag?
+	return request->answer = NULL;
+}
+
+static bool resolution_time_exceeded(struct kr_query *qry, uint64_t now)
+{
+	uint64_t resolving_time = now - qry->creation_time_mono;
+	if (resolving_time > KR_RESOLVE_TIME_LIMIT) {
+		WITH_VERBOSE(qry) {
+			VERBOSE_MSG(qry, "query resolution time limit exceeded\n");
+		}
+		return true;
+	}
+	return false;
+}
+
+int kr_resolve_consume(struct kr_request *request, struct kr_transport **transport, knot_pkt_t *packet)
+{
+	struct kr_rplan *rplan = &request->rplan;
+
+	/* Empty resolution plan, push packet as the new query */
+	if (packet && kr_rplan_empty(rplan)) {
+		return resolve_query(request, packet);
+	}
+
+	/* Different processing for network error */
+	struct kr_query *qry = array_tail(rplan->pending);
+	/* Check overall resolution time */
+	if (resolution_time_exceeded(qry, kr_now())) {
+		return KR_STATE_FAIL;
+	}
+	bool tried_tcp = (qry->flags.TCP);
+	if (!packet || packet->size == 0) {
+		return KR_STATE_PRODUCE;
+	} else {
+		/* Packet cleared, derandomize QNAME. */
+		knot_dname_t *qname_raw = knot_pkt_qname(packet);
+		if (qname_raw && qry->secret != 0) {
+			randomized_qname_case(qname_raw, qry->secret);
+		}
+		request->state = KR_STATE_CONSUME;
+		if (qry->flags.CACHED) {
+			ITERATE_LAYERS(request, qry, consume, packet);
+		} else {
+			/* Fill in source and latency information. */
+			request->upstream.rtt = kr_now() - qry->timestamp_mono;
+			request->upstream.transport = transport ? *transport : NULL;
+			ITERATE_LAYERS(request, qry, consume, packet);
+			/* Clear temporary information */
+			request->upstream.transport = NULL;
+			request->upstream.rtt = 0;
+		}
+	}
+
+	if (transport && !qry->flags.CACHED) {
+		if (!(request->state & KR_STATE_FAIL)) {
+			/* Do not complete NS address resolution on soft-fail. */
+			const int rcode = packet ? knot_wire_get_rcode(packet->wire) : 0;
+			if (rcode != KNOT_RCODE_SERVFAIL && rcode != KNOT_RCODE_REFUSED) {
+				qry->flags.AWAIT_IPV6 = false;
+				qry->flags.AWAIT_IPV4 = false;
+			}
+		}
+	}
+
+	if (request->state & KR_STATE_FAIL) {
+		qry->flags.RESOLVED = false;
+	}
+
+	if (!qry->flags.CACHED) {
+		if (request->state & KR_STATE_FAIL) {
+			if (++request->count_fail_row > KR_CONSUME_FAIL_ROW_LIMIT) {
+				if (VERBOSE_STATUS || kr_log_rtrace_enabled(request)) {
+					kr_log_req(request, 0, 2, "resl",
+						"=> too many failures in a row, "
+						"bail out (mitigation for NXNSAttack "
+						"CVE-2020-12667)\n");
+				}
+				if (!qry->flags.NO_NS_FOUND) {
+					qry->flags.NO_NS_FOUND = true;
+					return KR_STATE_PRODUCE;
+				}
+				return KR_STATE_FAIL;
+			}
+		} else {
+			request->count_fail_row = 0;
+		}
+	}
+
+	/* Pop query if resolved. */
+	if (request->state == KR_STATE_YIELD) {
+		return KR_STATE_PRODUCE; /* Requery */
+	} else if (qry->flags.RESOLVED) {
+		kr_rplan_pop(rplan, qry);
+	} else if (!tried_tcp && (qry->flags.TCP)) {
+		return KR_STATE_PRODUCE; /* Requery over TCP */
+	} else { /* Clear query flags for next attempt */
+		qry->flags.CACHED = false;
+		if (!request->options.TCP) {
+			qry->flags.TCP = false;
+		}
+	}
+
+	ITERATE_LAYERS(request, qry, reset);
+
+	/* Do not finish with bogus answer. */
+	if (qry->flags.DNSSEC_BOGUS)  {
+		if (qry->flags.FORWARD || qry->flags.STUB) {
+			return KR_STATE_FAIL;
+		}
+		/* Other servers might not have broken DNSSEC. */
+		qry->flags.DNSSEC_BOGUS = false;
+		return KR_STATE_PRODUCE;
+	}
+
+	return kr_rplan_empty(&request->rplan) ? KR_STATE_DONE : KR_STATE_PRODUCE;
+}
+
+/** @internal Spawn subrequest in current zone cut (no minimization or lookup). */
+static struct kr_query *zone_cut_subreq(struct kr_rplan *rplan, struct kr_query *parent,
+                           const knot_dname_t *qname, uint16_t qtype)
+{
+	struct kr_query *next = kr_rplan_push(rplan, parent, qname, parent->sclass, qtype);
+	if (!next) {
+		return NULL;
+	}
+	kr_zonecut_set(&next->zone_cut, parent->zone_cut.name);
+	if (kr_zonecut_copy(&next->zone_cut, &parent->zone_cut) != 0 ||
+	    kr_zonecut_copy_trust(&next->zone_cut, &parent->zone_cut) != 0) {
+		return NULL;
+	}
+	next->flags.NO_MINIMIZE = true;
+	if (parent->flags.DNSSEC_WANT) {
+		next->flags.DNSSEC_WANT = true;
+	}
+	return next;
+}
+
+static int forward_trust_chain_check(struct kr_request *request, struct kr_query *qry, bool resume)
+{
+	struct kr_rplan *rplan = &request->rplan;
+	map_t *trust_anchors = &request->ctx->trust_anchors;
+	map_t *negative_anchors = &request->ctx->negative_anchors;
+
+	if (qry->parent != NULL &&
+	    !(qry->forward_flags.CNAME) &&
+	    !(qry->flags.DNS64_MARK) &&
+	    knot_dname_in_bailiwick(qry->zone_cut.name, qry->parent->zone_cut.name) >= 0) {
+		return KR_STATE_PRODUCE;
+	}
+
+	assert(qry->flags.FORWARD);
+
+	if (!trust_anchors) {
+		qry->flags.AWAIT_CUT = false;
+		return KR_STATE_PRODUCE;
+	}
+
+	if (qry->flags.DNSSEC_INSECURE) {
+		qry->flags.AWAIT_CUT = false;
+		return KR_STATE_PRODUCE;
+	}
+
+	if (qry->forward_flags.NO_MINIMIZE) {
+		qry->flags.AWAIT_CUT = false;
+		return KR_STATE_PRODUCE;
+	}
+
+	const knot_dname_t *start_name = qry->sname;
+	if ((qry->flags.AWAIT_CUT) && !resume) {
+		qry->flags.AWAIT_CUT = false;
+		const knot_dname_t *longest_ta = kr_ta_get_longest_name(trust_anchors, qry->sname);
+		if (longest_ta) {
+			start_name = longest_ta;
+			qry->zone_cut.name = knot_dname_copy(start_name, qry->zone_cut.pool);
+			qry->flags.DNSSEC_WANT = true;
+		} else {
+			qry->flags.DNSSEC_WANT = false;
+			return KR_STATE_PRODUCE;
+		}
+	}
+
+	bool has_ta = (qry->zone_cut.trust_anchor != NULL);
+	knot_dname_t *ta_name = (has_ta ? qry->zone_cut.trust_anchor->owner : NULL);
+	bool refetch_ta = (!has_ta || !knot_dname_is_equal(qry->zone_cut.name, ta_name));
+	bool is_dnskey_subreq = kr_rplan_satisfies(qry, ta_name, KNOT_CLASS_IN, KNOT_RRTYPE_DNSKEY);
+	bool refetch_key = has_ta && (!qry->zone_cut.key || !knot_dname_is_equal(ta_name, qry->zone_cut.key->owner));
+	if (refetch_key && !is_dnskey_subreq) {
+		struct kr_query *next = zone_cut_subreq(rplan, qry, ta_name, KNOT_RRTYPE_DNSKEY);
+		if (!next) {
+			return KR_STATE_FAIL;
+		}
+		return KR_STATE_DONE;
+	}
+
+	int name_offset = 1;
+	const knot_dname_t *wanted_name;
+	bool nods, ds_req, ns_req, minimized, ns_exist;
+	do {
+		wanted_name = start_name;
+		ds_req = false;
+		ns_req = false;
+		ns_exist = true;
+
+		int cut_labels = knot_dname_labels(qry->zone_cut.name, NULL);
+		int wanted_name_labels = knot_dname_labels(wanted_name, NULL);
+		while (wanted_name[0] && wanted_name_labels > cut_labels + name_offset) {
+			wanted_name = knot_wire_next_label(wanted_name, NULL);
+			wanted_name_labels -= 1;
+		}
+		minimized = (wanted_name != qry->sname);
+
+		for (int i = 0; i < request->rplan.resolved.len; ++i) {
+			struct kr_query *q = request->rplan.resolved.at[i];
+			if (q->parent == qry &&
+			    q->sclass == qry->sclass &&
+			    (q->stype == KNOT_RRTYPE_DS || q->stype == KNOT_RRTYPE_NS) &&
+			    knot_dname_is_equal(q->sname, wanted_name)) {
+				if (q->stype == KNOT_RRTYPE_DS) {
+					ds_req = true;
+					if (q->flags.CNAME) {
+						ns_exist = false;
+					} else if (!(q->flags.DNSSEC_OPTOUT)) {
+						int ret = kr_dnssec_matches_name_and_type(&request->auth_selected, q->uid,
+											  wanted_name, KNOT_RRTYPE_NS);
+						ns_exist = (ret == kr_ok());
+					}
+				} else {
+					if (q->flags.CNAME) {
+						ns_exist = false;
+					}
+					ns_req = true;
+				}
+			}
+		}
+
+		if (ds_req && ns_exist && !ns_req && (minimized || resume)) {
+			struct kr_query *next = zone_cut_subreq(rplan, qry, wanted_name,
+								KNOT_RRTYPE_NS);
+			if (!next) {
+				return KR_STATE_FAIL;
+			}
+			return KR_STATE_DONE;
+		}
+
+		if (qry->parent == NULL && (qry->flags.CNAME) &&
+		    ds_req && ns_req) {
+			return KR_STATE_PRODUCE;
+		}
+
+		/* set `nods` */
+		if ((qry->stype == KNOT_RRTYPE_DS) &&
+	            knot_dname_is_equal(wanted_name, qry->sname)) {
+			nods = true;
+		} else if (resume && !ds_req) {
+			nods = false;
+		} else if (!minimized && qry->stype != KNOT_RRTYPE_DNSKEY) {
+			nods = true;
+		} else {
+			nods = ds_req;
+		}
+		name_offset += 1;
+	} while (ds_req && (ns_req || !ns_exist) && minimized);
+
+	/* Disable DNSSEC if it enters NTA. */
+	if (kr_ta_get(negative_anchors, wanted_name)){
+		VERBOSE_MSG(qry, ">< negative TA, going insecure\n");
+		qry->flags.DNSSEC_WANT = false;
+	}
+
+	/* Enable DNSSEC if enters a new island of trust. */
+	bool want_secured = (qry->flags.DNSSEC_WANT) &&
+			    !knot_wire_get_cd(request->qsource.packet->wire);
+	if (!(qry->flags.DNSSEC_WANT) &&
+	    !knot_wire_get_cd(request->qsource.packet->wire) &&
+	    kr_ta_get(trust_anchors, wanted_name)) {
+		qry->flags.DNSSEC_WANT = true;
+		want_secured = true;
+		WITH_VERBOSE(qry) {
+		KR_DNAME_GET_STR(qname_str, wanted_name);
+		VERBOSE_MSG(qry, ">< TA: '%s'\n", qname_str);
+		}
+	}
+
+	if (want_secured && !qry->zone_cut.trust_anchor) {
+		knot_rrset_t *ta_rr = kr_ta_get(trust_anchors, wanted_name);
+		if (!ta_rr) {
+			char name[] = "\0";
+			ta_rr = kr_ta_get(trust_anchors, (knot_dname_t*)name);
+		}
+		if (ta_rr) {
+			qry->zone_cut.trust_anchor = knot_rrset_copy(ta_rr, qry->zone_cut.pool);
+		}
+	}
+
+	has_ta = (qry->zone_cut.trust_anchor != NULL);
+	ta_name = (has_ta ? qry->zone_cut.trust_anchor->owner : NULL);
+	refetch_ta = (!has_ta || !knot_dname_is_equal(wanted_name, ta_name));
+	if (!nods && want_secured && refetch_ta) {
+		struct kr_query *next = zone_cut_subreq(rplan, qry, wanted_name,
+							KNOT_RRTYPE_DS);
+		if (!next) {
+			return KR_STATE_FAIL;
+		}
+		return KR_STATE_DONE;
+	}
+
+	/* Try to fetch missing DNSKEY.
+	 * Do not fetch if this is a DNSKEY subrequest to avoid circular dependency. */
+	is_dnskey_subreq = kr_rplan_satisfies(qry, ta_name, KNOT_CLASS_IN, KNOT_RRTYPE_DNSKEY);
+	refetch_key = has_ta && (!qry->zone_cut.key || !knot_dname_is_equal(ta_name, qry->zone_cut.key->owner));
+	if (want_secured && refetch_key && !is_dnskey_subreq) {
+		struct kr_query *next = zone_cut_subreq(rplan, qry, ta_name, KNOT_RRTYPE_DNSKEY);
+		if (!next) {
+			return KR_STATE_FAIL;
+		}
+		return KR_STATE_DONE;
+	}
+
+	return KR_STATE_PRODUCE;
+}
+
+/* @todo: Validator refactoring, keep this in driver for now. */
+static int trust_chain_check(struct kr_request *request, struct kr_query *qry)
+{
+	struct kr_rplan *rplan = &request->rplan;
+	map_t *trust_anchors = &request->ctx->trust_anchors;
+	map_t *negative_anchors = &request->ctx->negative_anchors;
+
+	/* Disable DNSSEC if it enters NTA. */
+	if (kr_ta_get(negative_anchors, qry->zone_cut.name)){
+		VERBOSE_MSG(qry, ">< negative TA, going insecure\n");
+		qry->flags.DNSSEC_WANT = false;
+		qry->flags.DNSSEC_INSECURE = true;
+	}
+	if (qry->flags.DNSSEC_NODS) {
+		/* This is the next query iteration with minimized qname.
+		 * At previous iteration DS non-existance has been proven */
+		VERBOSE_MSG(qry, "<= DS doesn't exist, going insecure\n");
+		qry->flags.DNSSEC_NODS = false;
+		qry->flags.DNSSEC_WANT = false;
+		qry->flags.DNSSEC_INSECURE = true;
+	}
+	/* Enable DNSSEC if entering a new (or different) island of trust,
+	 * and update the TA RRset if required. */
+	bool want_secured = (qry->flags.DNSSEC_WANT) &&
+			    !knot_wire_get_cd(request->qsource.packet->wire);
+	knot_rrset_t *ta_rr = kr_ta_get(trust_anchors, qry->zone_cut.name);
+	if (!knot_wire_get_cd(request->qsource.packet->wire) && ta_rr) {
+		qry->flags.DNSSEC_WANT = true;
+		want_secured = true;
+
+		if (qry->zone_cut.trust_anchor == NULL
+		    || !knot_dname_is_equal(qry->zone_cut.trust_anchor->owner, qry->zone_cut.name)) {
+			mm_free(qry->zone_cut.pool, qry->zone_cut.trust_anchor);
+			qry->zone_cut.trust_anchor = knot_rrset_copy(ta_rr, qry->zone_cut.pool);
+
+			WITH_VERBOSE(qry) {
+			KR_DNAME_GET_STR(qname_str, ta_rr->owner);
+			VERBOSE_MSG(qry, ">< TA: '%s'\n", qname_str);
+			}
+		}
+	}
+
+	/* Try to fetch missing DS (from above the cut). */
+	const bool has_ta = (qry->zone_cut.trust_anchor != NULL);
+	const knot_dname_t *ta_name = (has_ta ? qry->zone_cut.trust_anchor->owner : NULL);
+	const bool refetch_ta = !has_ta || !knot_dname_is_equal(qry->zone_cut.name, ta_name);
+	if (want_secured && refetch_ta) {
+		/* @todo we could fetch the information from the parent cut, but we don't remember that now */
+		struct kr_query *next = kr_rplan_push(rplan, qry, qry->zone_cut.name, qry->sclass, KNOT_RRTYPE_DS);
+		if (!next) {
+			return KR_STATE_FAIL;
+		}
+		next->flags.AWAIT_CUT = true;
+		next->flags.DNSSEC_WANT = true;
+		return KR_STATE_DONE;
+	}
+	/* Try to fetch missing DNSKEY (either missing or above current cut).
+	 * Do not fetch if this is a DNSKEY subrequest to avoid circular dependency. */
+	const bool is_dnskey_subreq = kr_rplan_satisfies(qry, ta_name, KNOT_CLASS_IN, KNOT_RRTYPE_DNSKEY);
+	const bool refetch_key = has_ta && (!qry->zone_cut.key || !knot_dname_is_equal(ta_name, qry->zone_cut.key->owner));
+	if (want_secured && refetch_key && !is_dnskey_subreq) {
+		struct kr_query *next = zone_cut_subreq(rplan, qry, ta_name, KNOT_RRTYPE_DNSKEY);
+		if (!next) {
+			return KR_STATE_FAIL;
+		}
+		return KR_STATE_DONE;
+	}
+
+	return KR_STATE_PRODUCE;
+}
+
+/** @internal Check current zone cut status and credibility, spawn subrequests if needed. */
+static int zone_cut_check(struct kr_request *request, struct kr_query *qry, knot_pkt_t *packet)
+/* TODO: using cache on this point in this way just isn't nice; remove in time */
+{
+	/* Stub mode, just forward and do not solve cut. */
+	if (qry->flags.STUB) {
+		return KR_STATE_PRODUCE;
+	}
+
+	/* Forwarding to upstream resolver mode.
+	 * Since forwarding targets already are in qry->ns -
+	 * cut fetching is not needed. */
+	if (qry->flags.FORWARD) {
+		return forward_trust_chain_check(request, qry, false);
+	}
+	if (!(qry->flags.AWAIT_CUT)) {
+		/* The query was resolved from cache.
+		 * Spawn DS \ DNSKEY requests if needed and exit */
+		return trust_chain_check(request, qry);
+	}
+
+	/* The query wasn't resolved from cache,
+	 * now it's the time to look up closest zone cut from cache. */
+	struct kr_cache *cache = &request->ctx->cache;
+	if (!kr_cache_is_open(cache)) {
+		int ret = kr_zonecut_set_sbelt(request->ctx, &qry->zone_cut);
+		if (ret != 0) {
+			return KR_STATE_FAIL;
+		}
+		VERBOSE_MSG(qry, "=> no cache open, using root hints\n");
+		qry->flags.AWAIT_CUT = false;
+		return KR_STATE_DONE;
+	}
+
+	const knot_dname_t *requested_name = qry->sname;
+	/* If at/subdomain of parent zone cut, start from its encloser.
+	 * This is for case when we get to a dead end
+	 * (and need glue from parent), or DS refetch. */
+	if (qry->parent) {
+		const knot_dname_t *parent = qry->parent->zone_cut.name;
+		if (parent[0] != '\0'
+		    && knot_dname_in_bailiwick(qry->sname, parent) >= 0) {
+			requested_name = knot_wire_next_label(parent, NULL);
+		}
+	} else if ((qry->stype == KNOT_RRTYPE_DS) && (qry->sname[0] != '\0')) {
+		/* If this is explicit DS query, start from encloser too. */
+		requested_name = knot_wire_next_label(requested_name, NULL);
+	}
+
+	int state = KR_STATE_FAIL;
+	do {
+		state = ns_fetch_cut(qry, requested_name, request, packet);
+		if (state == KR_STATE_DONE || (state & KR_STATE_FAIL)) {
+			return state;
+		} else if (state == KR_STATE_CONSUME) {
+			requested_name = knot_wire_next_label(requested_name, NULL);
+		}
+	} while (state == KR_STATE_CONSUME);
+
+	/* Update minimized QNAME if zone cut changed */
+	if (qry->zone_cut.name && qry->zone_cut.name[0] != '\0' && !(qry->flags.NO_MINIMIZE)) {
+		if (kr_make_query(qry, packet) != 0) {
+			return KR_STATE_FAIL;
+		}
+	}
+	qry->flags.AWAIT_CUT = false;
+
+	/* Check trust chain */
+	return trust_chain_check(request, qry);
+}
+
+
+static int ns_resolve_addr(struct kr_query *qry, struct kr_request *param, struct kr_transport *transport, uint16_t next_type)
+{
+	struct kr_rplan *rplan = &param->rplan;
+	struct kr_context *ctx = param->ctx;
+
+
+	/* Start NS queries from root, to avoid certain cases
+	 * where a NS drops out of cache and the rest is unavailable,
+	 * this would lead to dependency loop in current zone cut.
+	 */
+
+	/* Bail out if the query is already pending or dependency loop. */
+	if (!next_type || kr_rplan_satisfies(qry->parent, transport->ns_name, KNOT_CLASS_IN, next_type)) {
+		/* Fall back to SBELT if root server query fails. */
+		if (!next_type && qry->zone_cut.name[0] == '\0') {
+			VERBOSE_MSG(qry, "=> fallback to root hints\n");
+			kr_zonecut_set_sbelt(ctx, &qry->zone_cut);
+			return kr_error(EAGAIN);
+		}
+		/* No IPv4 nor IPv6, flag server as unusable. */
+		VERBOSE_MSG(qry, "=> unresolvable NS address, bailing out\n");
+		kr_zonecut_del_all(&qry->zone_cut, transport->ns_name);
+		return kr_error(EHOSTUNREACH);
+	}
+	/* Push new query to the resolution plan */
+	struct kr_query *next =
+		kr_rplan_push(rplan, qry, transport->ns_name, KNOT_CLASS_IN, next_type);
+	if (!next) {
+		return kr_error(ENOMEM);
+	}
+	next->flags.NONAUTH = true;
+
+	/* At the root level with no NS addresses, add SBELT subrequest. */
+	int ret = 0;
+	if (qry->zone_cut.name[0] == '\0') {
+		ret = kr_zonecut_set_sbelt(ctx, &next->zone_cut);
+		if (ret == 0) { /* Copy TA and key since it's the same cut to avoid lookup. */
+			kr_zonecut_copy_trust(&next->zone_cut, &qry->zone_cut);
+			kr_zonecut_set_sbelt(ctx, &qry->zone_cut); /* Add SBELT to parent in case query fails. */
+		}
+	} else {
+		next->flags.AWAIT_CUT = true;
+	}
+
+	if (ret == 0) {
+		if (next_type == KNOT_RRTYPE_AAAA) {
+			qry->flags.AWAIT_IPV6 = true;
+		} else {
+			qry->flags.AWAIT_IPV4 = true;
+		}	
+	}
+
+	return ret;
+}
+
+int kr_resolve_produce(struct kr_request *request, struct kr_transport **transport, knot_pkt_t *packet)
+{
+	struct kr_rplan *rplan = &request->rplan;
+
+	/* No query left for resolution */
+	if (kr_rplan_empty(rplan)) {
+		return KR_STATE_FAIL;
+	}
+
+	struct kr_query *qry = array_tail(rplan->pending);
+
+	/* Initialize server selection */
+	if (!qry->server_selection.initialized) {
+		kr_server_selection_init(qry);
+	}
+
+	/* If we have deferred answers, resume them. */
+	if (qry->deferred != NULL) {
+		/* @todo: Refactoring validator, check trust chain before resuming. */
+		int state = 0;
+		if (((qry->flags.FORWARD) == 0) ||
+		    ((qry->stype == KNOT_RRTYPE_DS) && (qry->flags.CNAME))) {
+			state = trust_chain_check(request, qry);
+		} else {
+			state = forward_trust_chain_check(request, qry, true);
+		}
+
+		switch(state) {
+		case KR_STATE_FAIL: return KR_STATE_FAIL;
+		case KR_STATE_DONE: return KR_STATE_PRODUCE;
+		default: break;
+		}
+		VERBOSE_MSG(qry, "=> resuming yielded answer\n");
+		struct kr_layer_pickle *pickle = qry->deferred;
+		request->state = KR_STATE_YIELD;
+		set_yield(&request->answ_selected, qry->uid, false);
+		set_yield(&request->auth_selected, qry->uid, false);
+		RESUME_LAYERS(layer_id(request, pickle->api), request, qry, consume, pickle->pkt);
+		if (request->state != KR_STATE_YIELD) {
+			/* No new deferred answers, take the next */
+			qry->deferred = pickle->next;
+		}
+	} else {
+		/* Caller is interested in always tracking a zone cut, even if the answer is cached
+		 * this is normally not required, and incurrs another cache lookups for cached answer. */
+		if (qry->flags.ALWAYS_CUT) {
+			if (!(qry->flags.STUB)) {
+				switch(zone_cut_check(request, qry, packet)) {
+				case KR_STATE_FAIL: return KR_STATE_FAIL;
+				case KR_STATE_DONE: return KR_STATE_PRODUCE;
+				default: break;
+				}
+			}
+		}
+		/* Resolve current query and produce dependent or finish */
+		request->state = KR_STATE_PRODUCE;
+		ITERATE_LAYERS(request, qry, produce, packet);
+		if (!(request->state & KR_STATE_FAIL) && knot_wire_get_qr(packet->wire)) {
+			/* Produced an answer from cache, consume it. */
+			qry->secret = 0;
+			request->state = KR_STATE_CONSUME;
+			ITERATE_LAYERS(request, qry, consume, packet);
+		}
+	}
+	switch(request->state) {
+	case KR_STATE_FAIL: return request->state;
+	case KR_STATE_CONSUME: break;
+	case KR_STATE_DONE:
+	default: /* Current query is done */
+		if (qry->flags.RESOLVED && request->state != KR_STATE_YIELD) {
+			kr_rplan_pop(rplan, qry);
+		}
+		ITERATE_LAYERS(request, qry, reset);
+		return kr_rplan_empty(rplan) ? KR_STATE_DONE : KR_STATE_PRODUCE;
+	}
+
+
+	/* This query has RD=0 or is ANY, stop here. */
+	if (qry->stype == KNOT_RRTYPE_ANY ||
+	    !knot_wire_get_rd(request->qsource.packet->wire)) {
+		VERBOSE_MSG(qry, "=> qtype is ANY or RD=0, bail out\n");
+		return KR_STATE_FAIL;
+	}
+
+	/* Update zone cut, spawn new subrequests. */
+	if (!(qry->flags.STUB)) {
+		int state = zone_cut_check(request, qry, packet);
+		switch(state) {
+		case KR_STATE_FAIL: return KR_STATE_FAIL;
+		case KR_STATE_DONE: return KR_STATE_PRODUCE;
+		default: break;
+		}
+	}
+
+
+	const struct kr_qflags qflg = qry->flags;
+	const bool retry = qflg.TCP || qflg.BADCOOKIE_AGAIN;
+	if (!qflg.FORWARD && !qflg.STUB && !retry) { /* Keep NS when requerying/stub/badcookie. */
+		/* Root DNSKEY must be fetched from the hints to avoid chicken and egg problem. */
+		if (qry->sname[0] == '\0' && qry->stype == KNOT_RRTYPE_DNSKEY) {
+			kr_zonecut_set_sbelt(request->ctx, &qry->zone_cut);
+		}
+	}
+
+	qry->server_selection.choose_transport(qry, transport);
+
+	if (*transport == NULL) {
+		/* Properly signal to serve_stale module. */
+		if (qry->flags.NO_NS_FOUND) {
+			ITERATE_LAYERS(request, qry, reset);
+			kr_rplan_pop(rplan, qry);
+			return KR_STATE_FAIL;
+		} else {
+			/* FIXME: This is probably quite inefficient:
+			* we go through the whole qr_task_step loop just because of the serve_stale
+			* module which might not even be loaded. */
+			qry->flags.NO_NS_FOUND = true;
+			return KR_STATE_PRODUCE;
+		}
+	}
+
+	if ((*transport)->protocol == KR_TRANSPORT_RESOLVE_A || (*transport)->protocol == KR_TRANSPORT_RESOLVE_AAAA) {
+		uint16_t type = (*transport)->protocol == KR_TRANSPORT_RESOLVE_A ? KNOT_RRTYPE_A : KNOT_RRTYPE_AAAA;
+		ns_resolve_addr(qry, qry->request, *transport, type);
+		ITERATE_LAYERS(request, qry, reset);
+		return KR_STATE_PRODUCE;
+	}
+
+	/* Randomize query case (if not in not turned off) */
+	qry->secret = qry->flags.NO_0X20 ? 0 : kr_rand_bytes(sizeof(qry->secret));
+	knot_dname_t *qname_raw = knot_pkt_qname(packet);
+	randomized_qname_case(qname_raw, qry->secret);
+
+	/*
+	 * Additional query is going to be finalized when calling
+	 * kr_resolve_checkout().
+	 */
+	qry->timestamp_mono = kr_now();
+	return request->state;
+}
+
+#if ENABLE_COOKIES
+/** Update DNS cookie data in packet. */
+static bool outbound_request_update_cookies(struct kr_request *req,
+                                            const struct sockaddr *src,
+                                            const struct sockaddr *dst)
+{
+	assert(req);
+
+	/* RFC7873 4.1 strongly requires server address. */
+	if (!dst) {
+		return false;
+	}
+
+	struct kr_cookie_settings *clnt_sett = &req->ctx->cookie_ctx.clnt;
+
+	/* Cookies disabled or packet has no EDNS section. */
+	if (!clnt_sett->enabled) {
+		return true;
+	}
+
+	/*
+	 * RFC7873 4.1 recommends using also the client address. The matter is
+	 * also discussed in section 6.
+	 */
+
+	kr_request_put_cookie(&clnt_sett->current, req->ctx->cache_cookie,
+	                      src, dst, req);
+
+	return true;
+}
+#endif /* ENABLE_COOKIES */
+
+int kr_resolve_checkout(struct kr_request *request, const struct sockaddr *src,
+                        struct kr_transport *transport, knot_pkt_t *packet)
+{
+	/* @todo: Update documentation if this function becomes approved. */
+
+	struct kr_rplan *rplan = &request->rplan;
+
+	if (knot_wire_get_qr(packet->wire) != 0) {
+		return kr_ok();
+	}
+
+	/* No query left for resolution */
+	if (kr_rplan_empty(rplan)) {
+		return kr_error(EINVAL);
+	}
+	struct kr_query *qry = array_tail(rplan->pending);
+
+#if ENABLE_COOKIES
+	/* Update DNS cookies in request. */
+	if (type == SOCK_DGRAM) { /* @todo: Add cookies also over TCP? */
+		/*
+		 * The actual server IP address is needed before generating the
+		 * actual cookie. If we don't know the server address then we
+		 * also don't know the actual cookie size.
+		 */
+		if (!outbound_request_update_cookies(request, src, &transport->address.ip)) {
+			return kr_error(EINVAL);
+		}
+	}
+#endif /* ENABLE_COOKIES */
+
+	int ret = query_finalize(request, qry, packet);
+	if (ret != 0) {
+		return kr_error(EINVAL);
+	}
+
+	/* Track changes in minimization secret to enable/disable minimization */
+	uint32_t old_minimization_secret = qry->secret;
+
+	/* Run the checkout layers and cancel on failure.
+	 * The checkout layer doesn't persist the state, so canceled subrequests
+	 * don't affect the resolution or rest of the processing. */
+	int type = -1;
+	switch(transport->protocol) {
+	case KR_TRANSPORT_UDP:
+		type = SOCK_DGRAM;
+		break;
+	case KR_TRANSPORT_TCP:
+	case KR_TRANSPORT_TLS:
+		type = SOCK_STREAM;
+		break;
+	default:
+		assert(0);
+	}
+	int state = request->state;
+	ITERATE_LAYERS(request, qry, checkout, packet, &transport->address.ip, type);
+	if (request->state & KR_STATE_FAIL) {
+		request->state = state; /* Restore */
+		return kr_error(ECANCELED);
+	}
+
+	/* Randomize query case (if secret changed) */
+	knot_dname_t *qname = knot_pkt_qname(packet);
+	if (qry->secret != old_minimization_secret) {
+		randomized_qname_case(qname, qry->secret);
+	}
+
+	/* Write down OPT unless in safemode */
+	if (!(qry->flags.NO_EDNS)) {
+		ret = edns_put(packet, true);
+		if (ret != 0) {
+			return kr_error(EINVAL);
+		}
+	}
+
+	WITH_VERBOSE(qry) {
+
+	KR_DNAME_GET_STR(qname_str, knot_pkt_qname(packet));
+	KR_DNAME_GET_STR(ns_name, transport->ns_name);
+	KR_DNAME_GET_STR(zonecut_str, qry->zone_cut.name);
+	KR_RRTYPE_GET_STR(type_str, knot_pkt_qtype(packet));
+	const char *ns_str = kr_straddr(&transport->address.ip);
+
+	VERBOSE_MSG(qry,
+			"=> id: '%05u' querying: '%s'@'%s' zone cut: '%s' "
+			"qname: '%s' qtype: '%s' proto: '%s'\n",
+			qry->id, ns_name, ns_str ? ns_str : "", zonecut_str,
+			qname_str, type_str, (qry->flags.TCP) ? "tcp" : "udp");
+	}
+
+	return kr_ok();
+}
+
+int kr_resolve_finish(struct kr_request *request, int state)
+{
+	request->state = state;
+	/* Finalize answer and construct whole wire-format (unless dropping). */
+	knot_pkt_t *answer = kr_request_ensure_answer(request);
+	if (answer) {
+		ITERATE_LAYERS(request, NULL, answer_finalize);
+		answer_finalize(request);
+
+		/* Defensive style, in case someone has forgotten.
+		 * Beware: non-empty answers do make sense even with SERVFAIL case, etc. */
+		if (request->state != KR_STATE_DONE) {
+			uint8_t *wire = answer->wire;
+			switch (knot_wire_get_rcode(wire)) {
+			case KNOT_RCODE_NOERROR:
+			case KNOT_RCODE_NXDOMAIN:
+				knot_wire_clear_ad(wire);
+				knot_wire_clear_aa(wire);
+				knot_wire_set_rcode(wire, KNOT_RCODE_SERVFAIL);
+			}
+		}
+	}
+
+	ITERATE_LAYERS(request, NULL, finish);
+
+#ifndef NOVERBOSELOG
+	struct kr_rplan *rplan = &request->rplan;
+	struct kr_query *last = kr_rplan_last(rplan);
+	VERBOSE_MSG(last, "finished in state: %d, queries: %zu, mempool: %zu B\n",
+	          request->state, rplan->resolved.len, (size_t) mp_total_size(request->pool.ctx));
+#endif
+
+	/* Trace request finish */
+	if (request->trace_finish) {
+		request->trace_finish(request);
+	}
+
+	/* Uninstall all tracepoints */
+	request->trace_finish = NULL;
+	request->trace_log = NULL;
+
+	return KR_STATE_DONE;
+}
+
+struct kr_rplan *kr_resolve_plan(struct kr_request *request)
+{
+	if (request) {
+		return &request->rplan;
+	}
+	return NULL;
+}
+
+knot_mm_t *kr_resolve_pool(struct kr_request *request)
+{
+	if (request) {
+		return &request->pool;
+	}
+	return NULL;
+}
+
+#undef VERBOSE_MSG
diff --git a/lib/resolve.h b/lib/resolve.h
new file mode 100644
index 0000000..8f2a338
--- /dev/null
+++ b/lib/resolve.h
@@ -0,0 +1,354 @@
+/*  Copyright (C) 2014-2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#pragma once
+
+#include <netinet/in.h>
+#include <sys/socket.h>
+#include <libknot/packet/pkt.h>
+
+#include "lib/cookies/control.h"
+#include "lib/cookies/lru_cache.h"
+#include "lib/layer.h"
+#include "lib/generic/map.h"
+#include "lib/generic/array.h"
+#include "lib/selection.h"
+#include "lib/rplan.h"
+#include "lib/module.h"
+#include "lib/cache/api.h"
+
+/**
+ * @file resolve.h
+ * @brief The API provides an API providing a "consumer-producer"-like interface to enable
+ * user to plug it into existing event loop or I/O code.
+ *
+ * # Example usage of the iterative API:
+ *
+ * @code{.c}
+ *
+ * // Create request and its memory pool
+ * struct kr_request req = {
+ * 	.pool = {
+ * 		.ctx = mp_new (4096),
+ * 		.alloc = (mm_alloc_t) mp_alloc
+ * 	}
+ * };
+ *
+ * // Setup and provide input query
+ * int state = kr_resolve_begin(&req, ctx);
+ * state = kr_resolve_consume(&req, query);
+ *
+ * // Generate answer
+ * while (state == KR_STATE_PRODUCE) {
+ *
+ *     // Additional query generate, do the I/O and pass back answer
+ *     state = kr_resolve_produce(&req, &addr, &type, query);
+ *     while (state == KR_STATE_CONSUME) {
+ *         int ret = sendrecv(addr, proto, query, resp);
+ *
+ *         // If I/O fails, make "resp" empty
+ *         state = kr_resolve_consume(&request, addr, resp);
+ *         knot_pkt_clear(resp);
+ *     }
+ *     knot_pkt_clear(query);
+ * }
+ *
+ * // "state" is either DONE or FAIL
+ * kr_resolve_finish(&request, state);
+ *
+ * @endcode
+ */
+
+
+struct kr_request;
+/** Allocate buffer for answer's wire (*maxlen may get lowered).
+ *
+ * Motivation: XDP wire allocation is an overlap of library and daemon:
+ *  - it needs to be called from the library
+ *  - it needs to rely on some daemon's internals
+ *  - the library (currently) isn't allowed to directly use symbols from daemon
+ *    (contrary to modules), e.g. some of our lib-using tests run without daemon
+ *
+ * Note: after we obtain the wire, we're obliged to send it out.
+ * (So far there's no use case to allow cancelling at that point.)
+ */
+typedef uint8_t * (*alloc_wire_f)(struct kr_request *req, uint16_t *maxlen);
+
+/**
+ * RRset rank - for cache and ranked_rr_*.
+ *
+ * The rank meaning consists of one independent flag - KR_RANK_AUTH,
+ * and the rest have meaning of values where only one can hold at any time.
+ * You can use one of the enums as a safe initial value, optionally | KR_RANK_AUTH;
+ * otherwise it's best to manipulate ranks via the kr_rank_* functions.
+ *
+ * @note The representation is complicated by restrictions on integer comparison:
+ * - AUTH must be > than !AUTH
+ * - AUTH INSECURE must be > than AUTH (because it attempted validation)
+ * - !AUTH SECURE must be > than AUTH (because it's valid)
+ *
+ * See also:
+ *   https://tools.ietf.org/html/rfc2181#section-5.4.1
+ *   https://tools.ietf.org/html/rfc4035#section-4.3
+ */
+enum kr_rank {
+	/* Initial-like states.  No validation has been attempted (yet). */
+	KR_RANK_INITIAL = 0, /**< Did not attempt to validate. It's assumed
+					compulsory to validate (or prove insecure). */
+	KR_RANK_OMIT,        /**< Do not attempt to validate.
+					(And don't consider it a validation failure.) */
+	KR_RANK_TRY,         /**< Attempt to validate, but failures are non-fatal. */
+
+	/* Failure states.  These have higher value because they have more information. */
+	KR_RANK_INDET = 4,   /**< Unable to determine whether it should be secure. */
+	KR_RANK_BOGUS,       /**< Ought to be secure but isn't. */
+	KR_RANK_MISMATCH,
+	KR_RANK_MISSING,     /**< No RRSIG found for that owner+type combination. */
+
+	/** Proven to be insecure, i.e. we have a chain of trust from TAs
+	 * that cryptographically denies the possibility of existence
+	 * of a positive chain of trust from the TAs to the record. */
+	KR_RANK_INSECURE = 8,
+
+	/** Authoritative data flag; the chain of authority was "verified".
+	 *  Even if not set, only in-bailiwick stuff is acceptable,
+	 *  i.e. almost authoritative (example: mandatory glue and its NS RR). */
+	KR_RANK_AUTH = 16,
+
+	KR_RANK_SECURE = 32,  /**< Verified whole chain of trust from the closest TA. */
+	/* @note Rank must not exceed 6 bits */
+};
+
+/** Check that a rank value is valid.  Meant for assertions. */
+bool kr_rank_check(uint8_t rank) KR_PURE;
+
+/** Test the presence of any flag/state in a rank, i.e. including KR_RANK_AUTH. */
+bool kr_rank_test(uint8_t rank, uint8_t kr_flag) KR_PURE KR_EXPORT;
+
+/** Set the rank state. The _AUTH flag is kept as it was. */
+static inline void kr_rank_set(uint8_t *rank, uint8_t kr_flag)
+{
+	assert(rank && kr_rank_check(*rank));
+	assert(kr_rank_check(kr_flag) && !(kr_flag & KR_RANK_AUTH));
+	*rank = kr_flag | (*rank & KR_RANK_AUTH);
+}
+
+
+/** @cond internal Array of modules. */
+typedef array_t(struct kr_module *) module_array_t;
+/* @endcond */
+
+/**
+ * Name resolution context.
+ *
+ * Resolution context provides basic services like cache, configuration and options.
+ *
+ * @note This structure is persistent between name resolutions and may
+ *       be shared between threads.
+ */
+struct kr_context
+{
+	/** Default kr_request flags.  For startup defaults see init_resolver() */
+	struct kr_qflags options;
+
+	/** Default EDNS towards *both* clients and upstream.
+	 * LATER: consider splitting the two, e.g. allow separately
+	 * configured limits for UDP packet size (say, LAN is under control). */
+	knot_rrset_t *downstream_opt_rr;
+	knot_rrset_t *upstream_opt_rr;
+
+	map_t trust_anchors;
+	map_t negative_anchors;
+	struct kr_zonecut root_hints;
+	struct kr_cache cache;
+	unsigned cache_rtt_tout_retry_interval;
+	module_array_t *modules;
+	/* The cookie context structure should not be held within the cookies
+	 * module because of better access. */
+	struct kr_cookie_ctx cookie_ctx;
+	kr_cookie_lru_t *cache_cookie;
+	int32_t tls_padding; /**< See net.tls_padding in ../daemon/README.rst -- -1 is "true" (default policy), 0 is "false" (no padding) */
+	knot_mm_t *pool;
+};
+
+/* Kept outside, because kres-gen.lua can't handle this depth
+ * (and lines here were too long anyway). */
+struct kr_request_qsource_flags {
+	bool tcp:1; /**< true if the request is not on UDP; only meaningful if (dst_addr). */
+	bool tls:1; /**< true if the request is encrypted; only meaningful if (dst_addr). */
+	bool http:1; /**< true if the request is on HTTP; only meaningful if (dst_addr). */
+	bool xdp:1; /**< true if the request is on AF_XDP; only meaningful if (dst_addr). */
+};
+
+typedef bool (*addr_info_f)(struct sockaddr*);
+typedef void (*async_resolution_f)(knot_dname_t*, enum knot_rr_type);
+typedef array_t(union inaddr) inaddr_array_t;
+
+/**
+ * Name resolution request.
+ *
+ * Keeps information about current query processing between calls to
+ * processing APIs, i.e. current resolved query, resolution plan, ...
+ * Use this instead of the simple interface if you want to implement
+ * multiplexing or custom I/O.
+ *
+ * @note All data for this request must be allocated from the given pool.
+ */
+struct kr_request {
+	struct kr_context *ctx;
+	knot_pkt_t *answer; /**< See kr_request_ensure_answer() */
+	struct kr_query *current_query;    /**< Current evaluated query. */
+	struct {
+		/** Address that originated the request. NULL for internal origin. */
+		const struct sockaddr *addr;
+		/** Address that accepted the request.  NULL for internal origin.
+		 * Beware: in case of UDP on wildcard address it will be wildcard;
+		 * closely related: issue #173. */
+		const struct sockaddr *dst_addr;
+		const knot_pkt_t *packet;
+		struct kr_request_qsource_flags flags; /**< See definition above. */
+		size_t size; /**< query packet size */
+		int32_t stream_id; /**< HTTP/2 stream ID for DoH requests */
+	} qsource;
+	struct {
+		unsigned rtt;                  /**< Current upstream RTT */
+		const struct kr_transport *transport;   /**< Current upstream transport */
+	} upstream;                        /**< Upstream information, valid only in consume() phase */
+	struct kr_qflags options;
+	int state;
+	ranked_rr_array_t answ_selected;
+	ranked_rr_array_t auth_selected;
+	ranked_rr_array_t add_selected;
+	bool answ_validated; /**< internal to validator; beware of caching, etc. */
+	bool auth_validated; /**< see answ_validated ^^ ; TODO */
+
+	/** Overall rank for the request.
+	 *
+	 * Values from kr_rank, currently just KR_RANK_SECURE and _INITIAL.
+	 * Only read this in finish phase and after validator, please.
+	 * Meaning of _SECURE: all RRs in answer+authority are _SECURE,
+	 *   including any negative results implied (NXDOMAIN, NODATA).
+	 */
+	uint8_t rank;
+
+	struct kr_rplan rplan;
+	trace_log_f trace_log; /**< Logging tracepoint */
+	trace_callback_f trace_finish; /**< Request finish tracepoint */
+	int vars_ref; /**< Reference to per-request variable table. LUA_NOREF if not set. */
+	knot_mm_t pool;
+	unsigned int uid; /**< for logging purposes only */
+	struct {
+		addr_info_f is_tls_capable;
+		addr_info_f is_tcp_connected;
+		addr_info_f is_tcp_waiting;
+		inaddr_array_t forwarding_targets; /**< When forwarding, possible targets are put here */
+	} selection_context;
+	unsigned int count_no_nsaddr;
+	unsigned int count_fail_row;
+	alloc_wire_f alloc_wire_cb; /**< CB to allocate answer wire (can be NULL). */
+};
+
+/** Initializer for an array of *_selected. */
+#define kr_request_selected(req) { \
+	[KNOT_ANSWER] = &(req)->answ_selected, \
+	[KNOT_AUTHORITY] = &(req)->auth_selected, \
+	[KNOT_ADDITIONAL] = &(req)->add_selected, \
+	}
+
+/**
+ * Begin name resolution.
+ *
+ * @note Expects a request to have an initialized mempool.
+ *
+ * @param request request state with initialized mempool
+ * @param ctx     resolution context
+ * @return        CONSUME (expecting query)
+ */
+KR_EXPORT
+int kr_resolve_begin(struct kr_request *request, struct kr_context *ctx);
+
+/**
+ * Ensure that request->answer is usable, and return it (for convenience).
+ *
+ * It may return NULL, in which case it marks ->state with _FAIL and no answer will be sent.
+ * Only use this when it's guaranteed that there will be no delay before sending it.
+ * You don't need to call this in places where "resolver knows" that there will be no delay,
+ * but even there you need to check if the ->answer is NULL (unless you check for _FAIL anyway).
+ */
+KR_EXPORT
+knot_pkt_t * kr_request_ensure_answer(struct kr_request *request);
+
+/**
+ * Consume input packet (may be either first query or answer to query originated from kr_resolve_produce())
+ *
+ * @note If the I/O fails, provide an empty or NULL packet, this will make iterator recognize nameserver failure.
+ *
+ * @param  request request state (awaiting input)
+ * @param  src     [in] packet source address
+ * @param  packet  [in] input packet
+ * @return         any state
+ */
+KR_EXPORT
+int kr_resolve_consume(struct kr_request *request, struct kr_transport **transport, knot_pkt_t *packet);
+
+/**
+ * Produce either next additional query or finish.
+ *
+ * If the CONSUME is returned then dst, type and packet will be filled with
+ * appropriate values and caller is responsible to send them and receive answer.
+ * If it returns any other state, then content of the variables is undefined.
+ *
+ * @param  request request state (in PRODUCE state)
+ * @param  dst     [out] possible address of the next nameserver
+ * @param  type    [out] possible used socket type (SOCK_STREAM, SOCK_DGRAM)
+ * @param  packet  [out] packet to be filled with additional query
+ * @return         any state
+ */
+KR_EXPORT
+int kr_resolve_produce(struct kr_request *request, struct kr_transport **transport, knot_pkt_t *packet);
+
+/**
+ * Finalises the outbound query packet with the knowledge of the IP addresses.
+ *
+ * @note The function must be called before actual sending of the request packet.
+ *
+ * @param  request request state (in PRODUCE state)
+ * @param  src     address from which the query is going to be sent
+ * @param  dst     address of the name server
+ * @param  type    used socket type (SOCK_STREAM, SOCK_DGRAM)
+ * @param  packet  [in,out] query packet to be finalised
+ * @return         kr_ok() or error code
+ */
+KR_EXPORT
+int kr_resolve_checkout(struct kr_request *request, const struct sockaddr *src,
+                        struct kr_transport *transport, knot_pkt_t *packet);
+
+/**
+ * Finish resolution and commit results if the state is DONE.
+ *
+ * @note The structures will be deinitialized, but the assigned memory pool is not going to
+ *       be destroyed, as it's owned by caller.
+ *
+ * @param  request request state
+ * @param  state   either DONE or FAIL state (to be assigned to request->state)
+ * @return         DONE
+ */
+KR_EXPORT
+int kr_resolve_finish(struct kr_request *request, int state);
+
+/**
+ * Return resolution plan.
+ * @param  request request state
+ * @return         pointer to rplan
+ */
+KR_EXPORT KR_PURE
+struct kr_rplan *kr_resolve_plan(struct kr_request *request);
+
+/**
+ * Return memory pool associated with request.
+ * @param  request request state
+ * @return         mempool
+ */
+KR_EXPORT KR_PURE
+knot_mm_t *kr_resolve_pool(struct kr_request *request);
diff --git a/lib/rplan.c b/lib/rplan.c
new file mode 100644
index 0000000..88dc12d
--- /dev/null
+++ b/lib/rplan.c
@@ -0,0 +1,296 @@
+/*  Copyright (C) 2014-2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#include <libknot/descriptor.h>
+#include <libknot/errcode.h>
+
+#include "lib/rplan.h"
+#include "lib/resolve.h"
+#include "lib/cache/api.h"
+#include "lib/defines.h"
+#include "lib/layer.h"
+
+#define VERBOSE_MSG(qry, ...) QRVERBOSE(qry, "plan",  __VA_ARGS__)
+
+inline static unsigned char chars_or(const unsigned char a, const unsigned char b)
+{
+	return a | b;
+}
+
+/** Bits set to 1 in variable b will be set to zero in variable a. */
+inline static unsigned char chars_mask(const unsigned char a, const unsigned char b)
+{
+	return a & ~b;
+}
+
+/** Apply mod(a, b) to every byte a, b from fl1, fl2 and return result in fl1. */
+inline static void kr_qflags_mod(struct kr_qflags *fl1, struct kr_qflags fl2,
+			unsigned char mod(const unsigned char a, const unsigned char b))
+{
+	if (!fl1) abort();
+	union {
+		struct kr_qflags flags;
+		/* C99 section 6.5.3.4: sizeof(char) == 1 */
+		unsigned char chars[sizeof(struct kr_qflags)];
+	} tmp1, tmp2;
+	/* The compiler should be able to optimize all this into simple ORs. */
+	tmp1.flags = *fl1;
+	tmp2.flags = fl2;
+	for (size_t i = 0; i < sizeof(struct kr_qflags); ++i) {
+		tmp1.chars[i] = mod(tmp1.chars[i], tmp2.chars[i]);
+	}
+	*fl1 = tmp1.flags;
+}
+
+/**
+ * Set bits from variable fl2 in variable fl1.
+ * Bits which are not set in fl2 are not modified in fl1.
+ *
+ * @param[in,out] fl1
+ * @param[in] fl2
+ */
+void kr_qflags_set(struct kr_qflags *fl1, struct kr_qflags fl2)
+{
+	kr_qflags_mod(fl1, fl2, chars_or);
+}
+
+/**
+ * Clear bits from variable fl2 in variable fl1.
+ * Bits which are not set in fl2 are not modified in fl1.
+ *
+ * @param[in,out] fl1
+ * @param[in] fl2
+ */
+void kr_qflags_clear(struct kr_qflags *fl1, struct kr_qflags fl2)
+{
+	kr_qflags_mod(fl1, fl2, chars_mask);
+}
+
+static struct kr_query *query_create(knot_mm_t *pool, const knot_dname_t *name, uint32_t uid)
+{
+	struct kr_query *qry = mm_calloc(pool, 1, sizeof(*qry));
+	if (qry == NULL) {
+		return NULL;
+	}
+
+	if (name != NULL) {
+		qry->sname = knot_dname_copy(name, pool);
+		if (qry->sname == NULL) {
+			mm_free(pool, qry);
+			return NULL;
+		}
+	}
+
+	knot_dname_to_lower(qry->sname);
+	qry->uid = uid;
+	return qry;
+}
+
+static void query_free(knot_mm_t *pool, struct kr_query *qry)
+{
+	kr_zonecut_deinit(&qry->zone_cut);
+	mm_free(pool, qry->sname);
+	mm_free(pool, qry);
+}
+
+int kr_rplan_init(struct kr_rplan *rplan, struct kr_request *request, knot_mm_t *pool)
+{
+	if (rplan == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	memset(rplan, 0, sizeof(struct kr_rplan));
+
+	rplan->pool = pool;
+	rplan->request = request;
+	array_init(rplan->pending);
+	array_init(rplan->resolved);
+	rplan->next_uid = 0;
+	return KNOT_EOK;
+}
+
+void kr_rplan_deinit(struct kr_rplan *rplan)
+{
+	if (rplan == NULL) {
+		return;
+	}
+
+	for (size_t i = 0; i < rplan->pending.len; ++i) {
+		query_free(rplan->pool, rplan->pending.at[i]);
+	}
+	for (size_t i = 0; i < rplan->resolved.len; ++i) {
+		query_free(rplan->pool, rplan->resolved.at[i]);
+	}
+	array_clear_mm(rplan->pending, mm_free, rplan->pool);
+	array_clear_mm(rplan->resolved, mm_free, rplan->pool);
+}
+
+bool kr_rplan_empty(struct kr_rplan *rplan)
+{
+	if (rplan == NULL) {
+		return true;
+	}
+
+	return rplan->pending.len == 0;
+}
+
+static struct kr_query *kr_rplan_push_query(struct kr_rplan *rplan,
+                                            struct kr_query *parent,
+                                            const knot_dname_t *name)
+{
+	if (rplan == NULL) {
+		return NULL;
+	}
+
+	/* Make sure there's enough space */
+	int ret = array_reserve_mm(rplan->pending, rplan->pending.len + 1, kr_memreserve, rplan->pool);
+	if (ret != 0) {
+		return NULL;
+	}
+
+	struct kr_query *qry = query_create(rplan->pool, name, rplan->next_uid);
+	if (qry == NULL) {
+		return NULL;
+	}
+	rplan->next_uid += 1;
+	/* Class and type must be set outside this function. */
+	qry->flags = rplan->request->options;
+	qry->parent = parent;
+	qry->request = rplan->request;
+
+	gettimeofday(&qry->timestamp, NULL);
+	qry->timestamp_mono = kr_now();
+	qry->creation_time_mono = parent ? parent->creation_time_mono : qry->timestamp_mono;
+	kr_zonecut_init(&qry->zone_cut, (const uint8_t *)"", rplan->pool);
+	qry->reorder = qry->flags.REORDER_RR ? kr_rand_bytes(sizeof(qry->reorder)) : 0;
+
+
+	assert((rplan->pending.len == 0 && rplan->resolved.len == 0)
+		== (rplan->initial == NULL));
+	if (rplan->initial == NULL) {
+		rplan->initial = qry;
+	}
+
+	array_push(rplan->pending, qry);
+
+	return qry;
+}
+
+struct kr_query *kr_rplan_push_empty(struct kr_rplan *rplan, struct kr_query *parent)
+{
+	if (rplan == NULL) {
+		return NULL;
+	}
+
+	struct kr_query *qry = kr_rplan_push_query(rplan, parent, NULL);
+	if (qry == NULL) {
+		return NULL;
+	}
+
+	WITH_VERBOSE(qry) {
+	VERBOSE_MSG(qry, "plan '%s' type '%s'  uid [%05u.%02u]\n", "", "",
+		    qry->request ? qry->request->uid : 0, qry->uid);
+	}
+	return qry;
+}
+
+struct kr_query *kr_rplan_push(struct kr_rplan *rplan, struct kr_query *parent,
+                               const knot_dname_t *name, uint16_t cls, uint16_t type)
+{
+	if (rplan == NULL || name == NULL) {
+		return NULL;
+	}
+
+	struct kr_query *qry = kr_rplan_push_query(rplan, parent, name);
+	if (qry == NULL) {
+		return NULL;
+	}
+
+	qry->sclass = cls;
+	qry->stype = type;
+
+	WITH_VERBOSE(qry) {
+	KR_DNAME_GET_STR(name_str, name);
+	KR_RRTYPE_GET_STR(type_str, type);
+	VERBOSE_MSG(parent, "plan '%s' type '%s' uid [%05u.%02u]\n",
+		    name_str, type_str,
+		    qry->request ? qry->request->uid : 0, qry->uid);
+	}
+	return qry;
+}
+
+int kr_rplan_pop(struct kr_rplan *rplan, struct kr_query *qry)
+{
+	if (rplan == NULL || qry == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	/* Make sure there's enough space */
+	int ret = array_reserve_mm(rplan->resolved, rplan->resolved.len + 1, kr_memreserve, rplan->pool);
+	if (ret != 0) {
+		return ret;
+	}
+
+	/* Find the query, it will likely be on top */
+	for (size_t i = rplan->pending.len; i > 0; i--) {
+		if (rplan->pending.at[i - 1] == qry) {
+			/* Delete i-1 element by *sliding* the rest,
+			 * contrary to array_del() */
+			for (size_t j = i; j < rplan->pending.len; ++j)
+				rplan->pending.at[j - 1] = rplan->pending.at[j];
+			array_pop(rplan->pending);
+
+			array_push(rplan->resolved, qry);
+			break;
+		}
+	}
+	return KNOT_EOK;
+}
+
+bool kr_rplan_satisfies(struct kr_query *closure, const knot_dname_t *name, uint16_t cls, uint16_t type)
+{
+	while (name && closure) {
+		if (closure->sclass == cls && closure->stype == type
+		    && knot_dname_is_equal(closure->sname, name)) {
+			return true;
+		}
+		closure = closure->parent;
+	}
+	return false;
+}
+
+struct kr_query *kr_rplan_resolved(struct kr_rplan *rplan)
+{
+	if (rplan->resolved.len == 0) {
+		return NULL;
+	}
+	return array_tail(rplan->resolved);
+}
+
+struct kr_query *kr_rplan_last(struct kr_rplan *rplan)
+{
+	if (!kr_rplan_empty(rplan)) {
+		return array_tail(rplan->pending);
+	}
+
+	return kr_rplan_resolved(rplan);
+}
+
+struct kr_query *kr_rplan_find_resolved(struct kr_rplan *rplan, struct kr_query *parent,
+                               const knot_dname_t *name, uint16_t cls, uint16_t type)
+{
+	struct kr_query *ret = NULL;
+	for (int i = 0; i < rplan->resolved.len; ++i) {
+		struct kr_query *q = rplan->resolved.at[i];
+		if (q->stype == type && q->sclass == cls &&
+		    (parent == NULL || q->parent == parent) &&
+		    knot_dname_is_equal(q->sname, name)) {
+			ret = q;
+			break;
+		}
+	}
+	return ret;
+}
+
+#undef VERBOSE_MSG
diff --git a/lib/rplan.h b/lib/rplan.h
new file mode 100644
index 0000000..a0f8f55
--- /dev/null
+++ b/lib/rplan.h
@@ -0,0 +1,218 @@
+/*  Copyright (C) 2014-2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#pragma once
+
+#include <sys/time.h>
+#include <libknot/dname.h>
+#include <libknot/codes.h>
+
+#include "lib/selection.h"
+#include "lib/cache/api.h"
+#include "lib/zonecut.h"
+
+/** Query flags */
+struct kr_qflags {
+	bool NO_MINIMIZE : 1;    /**< Don't minimize QNAME. */
+	bool NO_IPV6 : 1;        /**< Disable IPv6 */
+	bool NO_IPV4 : 1;        /**< Disable IPv4 */
+	bool TCP : 1;            /**< Use TCP (or TLS) for this query. */
+	bool RESOLVED : 1;       /**< Query is resolved.  Note that kr_query gets
+				  *   RESOLVED before following a CNAME chain; see .CNAME. */
+	bool AWAIT_IPV4 : 1;     /**< Query is waiting for A address. */
+	bool AWAIT_IPV6 : 1;     /**< Query is waiting for AAAA address. */
+	bool AWAIT_CUT : 1;      /**< Query is waiting for zone cut lookup */
+	bool NO_EDNS : 1;        /**< Don't use EDNS. */
+	bool CACHED : 1;         /**< Query response is cached. */
+	bool NO_CACHE : 1;       /**< No cache for lookup; exception: finding NSs and subqueries. */
+	bool EXPIRING : 1;       /**< Query response is cached but expiring.  See is_expiring(). */
+	bool ALLOW_LOCAL : 1;    /**< Allow queries to local or private address ranges. */
+	bool DNSSEC_WANT : 1;    /**< Want DNSSEC secured answer; exception: +cd,
+				  * i.e. knot_wire_get_cd(request->qsource.packet->wire) */
+	bool DNSSEC_BOGUS : 1;   /**< Query response is DNSSEC bogus. */
+	bool DNSSEC_INSECURE : 1;/**< Query response is DNSSEC insecure. */
+	bool DNSSEC_CD : 1;      /**< Instruction to set CD bit in request. */
+	bool STUB : 1;           /**< Stub resolution, accept received answer as solved. */
+	bool ALWAYS_CUT : 1;     /**< Always recover zone cut (even if cached). */
+	bool DNSSEC_WEXPAND : 1; /**< Query response has wildcard expansion. */
+	bool PERMISSIVE : 1;     /**< Permissive resolver mode. */
+	bool STRICT : 1;         /**< Strict resolver mode. */
+	bool BADCOOKIE_AGAIN : 1;/**< Query again because bad cookie returned. */
+	bool CNAME : 1;          /**< Query response contains CNAME in answer section. */
+	bool REORDER_RR : 1;     /**< Reorder cached RRs. */
+	bool TRACE : 1;          /**< Also log answers if --verbose. */
+	bool NO_0X20 : 1;        /**< Disable query case randomization . */
+	bool DNSSEC_NODS : 1;    /**< DS non-existance is proven */
+	bool DNSSEC_OPTOUT : 1;  /**< Closest encloser proof has optout */
+	bool NONAUTH : 1;        /**< Non-authoritative in-bailiwick records are enough.
+				  * TODO: utilize this also outside cache. */
+	bool FORWARD : 1;        /**< Forward all queries to upstream; validate answers. */
+	bool DNS64_MARK : 1;     /**< Internal mark for dns64 module. */
+	bool CACHE_TRIED : 1;    /**< Internal to cache module. */
+	bool NO_NS_FOUND : 1;    /**< No valid NS found during last PRODUCE stage. */
+	bool PKT_IS_SANE : 1;    /**< Set by iterator in consume phase to indicate whether
+				  * some basic aspects of the packet are OK, e.g. QNAME. */
+};
+
+/** Combine flags together.  This means set union for simple flags. */
+KR_EXPORT
+void kr_qflags_set(struct kr_qflags *fl1, struct kr_qflags fl2);
+
+/** Remove flags.  This means set-theoretic difference. */
+KR_EXPORT
+void kr_qflags_clear(struct kr_qflags *fl1, struct kr_qflags fl2);
+
+/** Callback for serve-stale decisions.
+ * @param ttl the expired TTL (i.e. it's < 0)
+ * @return the adjusted TTL (typically 1) or < 0.
+ */
+typedef int32_t (*kr_stale_cb)(int32_t ttl, const knot_dname_t *owner, uint16_t type,
+				const struct kr_query *qry);
+
+/**
+ * Single query representation.
+ */
+struct kr_query {
+	struct kr_query *parent;
+	knot_dname_t *sname; /**< The name to resolve - lower-cased, uncompressed. */
+	uint16_t stype;
+	uint16_t sclass;
+	uint16_t id;
+	uint16_t reorder; /**< Seed to reorder (cached) RRs in answer or zero. */
+	struct kr_qflags flags;
+	struct kr_qflags forward_flags;
+	uint32_t secret;
+	uint32_t uid; /**< Query iteration number, unique within the kr_rplan. */
+	uint64_t creation_time_mono; /* The time of query's creation (milliseconds).
+				 * Or time of creation of an oldest
+				 * ancestor if it is a subquery. */
+	uint64_t timestamp_mono; /**< Time of query created or time of
+	                           * query to upstream resolver (milliseconds). */
+	struct timeval timestamp; /**< Real time for TTL+DNSSEC checks (.tv_sec only). */
+	struct kr_zonecut zone_cut;
+	struct kr_layer_pickle *deferred;
+
+	/** Current xNAME depth, set by iterator.  0 = uninitialized, 1 = no CNAME, ...
+	 * See also KR_CNAME_CHAIN_LIMIT. */
+	int8_t cname_depth;
+	/** Pointer to the query that originated this one because of following a CNAME (or NULL). */
+	struct kr_query *cname_parent;
+	struct kr_request *request; /**< Parent resolution request. */
+	kr_stale_cb stale_cb; /**< See the type */
+	struct kr_server_selection server_selection;
+};
+
+/** @cond internal Array of queries. */
+typedef array_t(struct kr_query *) kr_qarray_t;
+/* @endcond */
+
+/**
+ * Query resolution plan structure.
+ *
+ * The structure most importantly holds the original query, answer and the
+ * list of pending queries required to resolve the original query.
+ * It also keeps a notion of current zone cut.
+ */
+struct kr_rplan {
+	kr_qarray_t pending;        /**< List of pending queries.
+					Beware: order is significant ATM,
+					as the last is the next one to solve,
+					and they may be inter-dependent. */
+	kr_qarray_t resolved;       /**< List of resolved queries. */
+	struct kr_query *initial;   /**< The initial query (also in pending or resolved). */
+
+	struct kr_request *request; /**< Parent resolution request. */
+	knot_mm_t *pool;            /**< Temporary memory pool. */
+	uint32_t next_uid;          /**< Next value for kr_query::uid (incremental). */
+};
+
+/**
+ * Initialize resolution plan (empty).
+ * @param rplan plan instance
+ * @param request resolution request
+ * @param pool ephemeral memory pool for whole resolution
+ */
+KR_EXPORT
+int kr_rplan_init(struct kr_rplan *rplan, struct kr_request *request, knot_mm_t *pool);
+
+/**
+ * Deinitialize resolution plan, aborting any uncommited transactions.
+ * @param rplan plan instance
+ */
+KR_EXPORT
+void kr_rplan_deinit(struct kr_rplan *rplan);
+
+/**
+ * Return true if the resolution plan is empty (i.e. finished or initialized)
+ * @param rplan plan instance
+ * @return true or false
+ */
+KR_EXPORT KR_PURE
+bool kr_rplan_empty(struct kr_rplan *rplan);
+
+/**
+ * Push empty query to the top of the resolution plan.
+ * @note This query serves as a cookie query only.
+ * @param rplan plan instance
+ * @param parent query parent (or NULL)
+ * @return query instance or NULL
+ */
+KR_EXPORT
+struct kr_query *kr_rplan_push_empty(struct kr_rplan *rplan,
+                                     struct kr_query *parent);
+
+/**
+ * Push a query to the top of the resolution plan.
+ * @note This means that this query takes precedence before all pending queries.
+ * @param rplan plan instance
+ * @param parent query parent (or NULL)
+ * @param name resolved name
+ * @param cls  resolved class
+ * @param type resolved type
+ * @return query instance or NULL
+ */
+KR_EXPORT
+struct kr_query *kr_rplan_push(struct kr_rplan *rplan, struct kr_query *parent,
+                               const knot_dname_t *name, uint16_t cls, uint16_t type);
+
+/**
+ * Pop existing query from the resolution plan.
+ * @note Popped queries are not discarded, but moved to the resolved list.
+ * @param rplan plan instance
+ * @param qry resolved query
+ * @return 0 or an error
+ */
+KR_EXPORT
+int kr_rplan_pop(struct kr_rplan *rplan, struct kr_query *qry);
+
+/**
+ * Return true if resolution chain satisfies given query.
+ */
+KR_EXPORT KR_PURE
+bool kr_rplan_satisfies(struct kr_query *closure, const knot_dname_t *name, uint16_t cls, uint16_t type);
+
+/** Return last resolved query. */
+KR_EXPORT KR_PURE
+struct kr_query *kr_rplan_resolved(struct kr_rplan *rplan);
+
+/**
+  * Return last query (either currently being solved or last resolved).
+  * This is necessary to retrieve the last query in case of resolution failures (e.g. time limit reached).
+  */
+KR_EXPORT KR_PURE
+struct kr_query *kr_rplan_last(struct kr_rplan *rplan);
+
+
+/**
+ * Check if a given query already resolved.
+ * @param rplan plan instance
+ * @param parent query parent (or NULL)
+ * @param name resolved name
+ * @param cls  resolved class
+ * @param type resolved type
+ * @return query instance or NULL
+ */
+KR_EXPORT KR_PURE
+struct kr_query *kr_rplan_find_resolved(struct kr_rplan *rplan, struct kr_query *parent,
+                               const knot_dname_t *name, uint16_t cls, uint16_t type);
diff --git a/lib/selection.c b/lib/selection.c
new file mode 100644
index 0000000..56530cb
--- /dev/null
+++ b/lib/selection.c
@@ -0,0 +1,751 @@
+#include <libknot/dname.h>
+
+#include "lib/selection.h"
+#include "lib/selection_forward.h"
+#include "lib/selection_iter.h"
+#include "lib/generic/pack.h"
+#include "lib/generic/trie.h"
+#include "lib/rplan.h"
+#include "lib/cache/api.h"
+#include "lib/resolve.h"
+
+#include "daemon/worker.h"
+#include "daemon/tls.h"
+
+#include "lib/utils.h"
+
+#define VERBOSE_MSG(qry, ...) QRVERBOSE((qry), "slct", __VA_ARGS__)
+
+#define DEFAULT_TIMEOUT 400
+#define MAX_TIMEOUT 10000
+#define EXPLORE_TIMEOUT_COEFFICIENT 2
+#define MAX_BACKOFF 5
+#define MINIMAL_TIMEOUT_ADDITION 20
+
+/* After TCP_TIMEOUT_THRESHOLD timeouts one transport, we'll switch to TCP. */
+#define TCP_TIMEOUT_THRESHOLD 2
+/* If the expected RTT is over TCP_RTT_THRESHOLD we switch to TCP instead. */
+#define TCP_RTT_THRESHOLD 2000
+
+/* Define ε for ε-greedy algorithm (see select_transport)
+ * as ε=EPSILON_NOMIN/EPSILON_DENOM */
+#define EPSILON_NOMIN 1
+#define EPSILON_DENOM 20
+
+static const char *kr_selection_error_str(enum kr_selection_error err) {
+	switch (err) {
+	#define X(ENAME) case KR_SELECTION_ ## ENAME: return #ENAME
+		X(OK);
+		X(QUERY_TIMEOUT);
+		X(TLS_HANDSHAKE_FAILED);
+		X(TCP_CONNECT_FAILED);
+		X(TCP_CONNECT_TIMEOUT);
+		X(REFUSED);
+		X(SERVFAIL);
+		X(FORMERR);
+		X(FORMERR_EDNS);
+		X(NOTIMPL);
+		X(OTHER_RCODE);
+		X(MALFORMED);
+		X(MISMATCHED);
+		X(TRUNCATED);
+		X(DNSSEC_ERROR);
+		X(LAME_DELEGATION);
+		X(BAD_CNAME);
+		case KR_SELECTION_NUMBER_OF_ERRORS: break; // not a valid code
+	#undef X
+	}
+	assert(false); // we want to define all; compiler helps by -Wswitch (no default:)
+	return NULL;
+}
+
+
+/* Simple detection of IPv6 being broken.
+ *
+ * We follow all IPv6 timeouts and successes.  Consider it broken iff we've had
+ * timeouts on several different IPv6 prefixes since the last IPv6 success.
+ * Note: unlike the rtt_state, this happens only per-process (for simplicity).
+ *
+ * ## NO6_PREFIX_* choice
+ *   For our practical use we choose primarily based on root and typical TLD servers.
+ *   Looking at *.{root,gtld}-servers.net, we have 7/26 AAAAs in 2001:500:00**::
+ *   but adding one more byte makes these completely unique, so we choose /48.
+ *   As distribution to ASs seems to be on shorter prefixes (RIPE: /32 -- /24?),
+ *   we wait for several distinct prefixes.
+ */
+
+#define NO6_PREFIX_COUNT 6
+#define NO6_PREFIX_BYTES (48/8)
+static struct {
+	int len_used;
+	uint8_t addr_prefixes[NO6_PREFIX_COUNT][NO6_PREFIX_BYTES];
+} no6_est = { .len_used = 0 };
+
+static inline bool no6_is_bad(void)
+{
+	return no6_est.len_used == NO6_PREFIX_COUNT;
+}
+
+static void no6_timeouted(const struct kr_query *qry, const uint8_t *addr)
+{
+	if (no6_is_bad()) { // we can't get worse
+		VERBOSE_MSG(qry, "NO6: timeouted, but bad already\n");
+		return;
+	}
+	// If we have the address already, do nothing.
+	for (int i = 0; i < no6_est.len_used; ++i) {
+		if (memcmp(addr, no6_est.addr_prefixes[i], NO6_PREFIX_BYTES) == 0) {
+			VERBOSE_MSG(qry, "NO6: timeouted, repeated prefix, timeouts %d/%d\n",
+					no6_est.len_used, (int)NO6_PREFIX_COUNT);
+			return;
+		}
+	}
+	// Append!
+	memcpy(no6_est.addr_prefixes[no6_est.len_used++], addr, NO6_PREFIX_BYTES);
+	VERBOSE_MSG(qry, "NO6: timeouted, appended, timeouts %d/%d\n",
+			no6_est.len_used, (int)NO6_PREFIX_COUNT);
+}
+
+static inline void no6_success(const struct kr_query *qry)
+{
+	if (no6_est.len_used) {
+		VERBOSE_MSG(qry, "NO6: success, zeroing %d/%d\n",
+				no6_est.len_used, (int)NO6_PREFIX_COUNT);
+	}
+	no6_est.len_used = 0;
+}
+
+
+/* Simple cache interface follows */
+
+static knot_db_val_t cache_key(const uint8_t *ip, size_t len)
+{
+	// CACHE_KEY_DEF: '\0' + 'S' + raw IP
+	const size_t key_len = len + 2;
+	uint8_t *key_data = malloc(key_len);
+	key_data[0] = '\0';
+	key_data[1] = 'S';
+	memcpy(key_data + 2, ip, len);
+	knot_db_val_t key = {
+		.len = key_len,
+		.data = key_data,
+	};
+	return key;
+}
+
+/* First value of timeout will be calculated as SRTT+4*VARIANCE
+ * by calc_timeout(), so it'll be equal to DEFAULT_TIMEOUT. */
+static const struct rtt_state default_rtt_state = { .srtt = 0,
+						    .variance = DEFAULT_TIMEOUT / 4,
+						    .consecutive_timeouts = 0,
+						    .dead_since = 0 };
+
+struct rtt_state get_rtt_state(const uint8_t *ip, size_t len,
+			       struct kr_cache *cache)
+{
+	struct rtt_state state;
+	knot_db_val_t value;
+	knot_db_t *db = cache->db;
+	struct kr_cdb_stats *stats = &cache->stats;
+
+	knot_db_val_t key = cache_key(ip, len);
+
+	if (cache->api->read(db, stats, &key, &value, 1)) {
+		state = default_rtt_state;
+	} else if (value.len != sizeof(struct rtt_state)) {
+		assert(false); // shouldn't happen but let's be more robust
+		state = default_rtt_state;
+	} else {
+		state = *(struct rtt_state *)value.data;
+	}
+
+	free(key.data);
+	return state;
+}
+
+int put_rtt_state(const uint8_t *ip, size_t len, struct rtt_state state,
+		  struct kr_cache *cache)
+{
+	knot_db_t *db = cache->db;
+	struct kr_cdb_stats *stats = &cache->stats;
+
+	knot_db_val_t key = cache_key(ip, len);
+	knot_db_val_t value = { .len = sizeof(struct rtt_state),
+				.data = &state };
+
+	int ret = cache->api->write(db, stats, &key, &value, 1);
+	cache->api->commit(db, stats);
+
+	free(key.data);
+	return ret;
+}
+
+void bytes_to_ip(uint8_t *bytes, size_t len, uint16_t port, union inaddr *dst)
+{
+	switch (len) {
+	case sizeof(struct in_addr):
+		dst->ip4.sin_family = AF_INET;
+		memcpy(&dst->ip4.sin_addr, bytes, len);
+		dst->ip4.sin_port = htons(port);
+		break;
+	case sizeof(struct in6_addr):
+		memset(&dst->ip6, 0, sizeof(dst->ip6)); // avoid uninit surprises
+		dst->ip6.sin6_family = AF_INET6;
+		memcpy(&dst->ip6.sin6_addr, bytes, len);
+		dst->ip6.sin6_port = htons(port);
+		break;
+	default:
+		assert(0);
+	}
+}
+
+uint8_t *ip_to_bytes(const union inaddr *src, size_t len)
+{
+	switch (len) {
+	case sizeof(struct in_addr):
+		return (uint8_t *)&src->ip4.sin_addr;
+	case sizeof(struct in6_addr):
+		return (uint8_t *)&src->ip6.sin6_addr;
+	default:
+		assert(0);
+		return NULL;
+	}
+}
+
+static bool no_rtt_info(struct rtt_state s)
+{
+	return s.srtt == 0 && s.consecutive_timeouts == 0;
+}
+
+static unsigned back_off_timeout(uint32_t to, int pow)
+{
+	pow = MIN(pow, MAX_BACKOFF);
+	to <<= pow;
+	return MIN(to, MAX_TIMEOUT);
+}
+
+/* This is verbatim (minus the default timeout value and minimal variance)
+ * RFC6298, sec. 2. */
+static unsigned calc_timeout(struct rtt_state state)
+{
+	int32_t timeout = state.srtt + MAX(4 * state.variance, MINIMAL_TIMEOUT_ADDITION);
+	return back_off_timeout(timeout, state.consecutive_timeouts);
+}
+
+/* This is verbatim RFC6298, sec. 2. */
+static struct rtt_state calc_rtt_state(struct rtt_state old, unsigned new_rtt)
+{
+	if (no_rtt_info(old)) {
+		return (struct rtt_state){ new_rtt, new_rtt / 2, 0 };
+	}
+
+	struct rtt_state ret = { 0 };
+	ret.variance = (3 * old.variance + abs(old.srtt - (int32_t)new_rtt)
+			+ 2/*rounding*/) / 4;
+	ret.srtt = (7 * old.srtt + new_rtt + 4/*rounding*/) / 8;
+
+	return ret;
+}
+
+/**
+ * @internal Invalidate addresses which should be considered dead
+ */
+static void invalidate_dead_upstream(struct address_state *state,
+				     unsigned int retry_timeout)
+{
+	struct rtt_state *rs = &state->rtt_state;
+	if (rs->consecutive_timeouts >= KR_NS_TIMEOUT_ROW_DEAD) {
+		uint64_t now = kr_now();
+		if (now < rs->dead_since) {
+			// broken continuity of timestamp (reboot, different machine, etc.)
+			*rs = default_rtt_state;
+		} else if (now < rs->dead_since + retry_timeout) {
+			// period when we don't want to use the address
+			state->generation = -1;
+		} else {
+			assert(now >= rs->dead_since + retry_timeout);
+			// we allow to retry the server now
+			// TODO: perhaps tweak *rs?
+		}
+	}
+}
+
+/**
+ * @internal Check if IP address is TLS capable.
+ *
+ * @p req has to have the selection_context properly initiazed.
+ */
+static void check_tls_capable(struct address_state *address_state,
+			      struct kr_request *req, struct sockaddr *address)
+{
+	address_state->tls_capable =
+		req->selection_context.is_tls_capable ?
+			      req->selection_context.is_tls_capable(address) :
+			      false;
+}
+
+#if 0
+/* TODO: uncomment these once we actually use the information it collects. */
+/**
+ * Check if there is a existing TCP connection to this address.
+ *
+ * @p req has to have the selection_context properly initiazed.
+ */
+void check_tcp_connections(struct address_state *address_state, struct kr_request *req, struct sockaddr *address) {
+	address_state->tcp_connected = req->selection_context.is_tcp_connected ? req->selection_context.is_tcp_connected(address) : false;
+	address_state->tcp_waiting = req->selection_context.is_tcp_waiting ? req->selection_context.is_tcp_waiting(address) : false;
+}
+#endif
+
+/**
+ * @internal Invalidate address if the respective IP version is disabled.
+ */
+static void check_network_settings(struct address_state *address_state,
+				   size_t address_len, bool no_ipv4, bool no_ipv6)
+{
+	if (no_ipv4 && address_len == sizeof(struct in_addr)) {
+		address_state->generation = -1;
+	}
+	if (no_ipv6 && address_len == sizeof(struct in6_addr)) {
+		address_state->generation = -1;
+	}
+}
+
+void update_address_state(struct address_state *state, union inaddr *address,
+			  size_t address_len, struct kr_query *qry)
+{
+	check_tls_capable(state, qry->request, &address->ip);
+	/* TODO: uncomment this once we actually use the information it collects
+	check_tcp_connections(address_state, qry->request, &address->ip);
+	*/
+	check_network_settings(state, address_len, qry->flags.NO_IPV4,
+			       qry->flags.NO_IPV6);
+	state->rtt_state =
+		get_rtt_state(ip_to_bytes(address, address_len),
+		              address_len, &qry->request->ctx->cache);
+	invalidate_dead_upstream(
+		state, qry->request->ctx->cache_rtt_tout_retry_interval);
+#ifdef SELECTION_CHOICE_LOGGING
+	// This is sometimes useful for debugging, but usually too verbose
+	WITH_VERBOSE(qry)
+	{
+		const char *ns_str = kr_straddr(&address->ip);
+		VERBOSE_MSG(qry, "rtt of %s is %d, variance is %d\n", ns_str,
+			    state->rtt_state.srtt, state->rtt_state.variance);
+	}
+#endif
+}
+
+static int cmp_choices(const void *a, const void *b)
+{
+	const struct choice *a_ = a;
+	const struct choice *b_ = b;
+
+	int diff;
+	/* Prefer IPv4 if IPv6 appears to be generally broken. */
+	diff = (int)a_->address_len - (int)b_->address_len;
+	if (diff && no6_is_bad()) {
+		return diff;
+	}
+	/* Address with no RTT information is better than address
+	 * with some information. */
+	if ((diff = no_rtt_info(b_->address_state->rtt_state) -
+		    no_rtt_info(a_->address_state->rtt_state))) {
+		return diff;
+	}
+	/* Address with less errors is better. */
+	if ((diff = a_->address_state->error_count -
+		    b_->address_state->error_count)) {
+		return diff;
+	}
+	/* Address with smaller expected timeout is better. */
+	if ((diff = calc_timeout(a_->address_state->rtt_state) -
+		    calc_timeout(b_->address_state->rtt_state))) {
+		return diff;
+	}
+	return 0;
+}
+
+/* Fisher-Yates shuffle of the choices */
+static void shuffle_choices(struct choice choices[], int choices_len)
+{
+	struct choice tmp;
+	for (int i = choices_len - 1; i > 0; i--) {
+		int j = kr_rand_bytes(1) % (i + 1);
+		tmp = choices[i];
+		choices[i] = choices[j];
+		choices[j] = tmp;
+	}
+}
+
+/* Performs the actual selection (currently variation on epsilon-greedy). */
+struct kr_transport *select_transport(struct choice choices[], int choices_len,
+				      struct to_resolve unresolved[],
+				      int unresolved_len, int timeouts,
+				      struct knot_mm *mempool, bool tcp,
+				      size_t *choice_index)
+{
+	if (!choices_len && !unresolved_len) {
+		/* There is nothing to choose from */
+		return NULL;
+	}
+
+	struct kr_transport *transport = mm_calloc(mempool, 1, sizeof(*transport));
+
+	/* Shuffle, so we choose fairly between choices with same attributes. */
+	shuffle_choices(choices, choices_len);
+	/* If there are some addresses with no rtt_info we try them
+	 * first (see cmp_choices). So unknown servers are chosen
+	 * *before* the best know server. This ensures that every option
+	 * is tried before going back to some that was tried before. */
+	qsort(choices, choices_len, sizeof(struct choice), cmp_choices);
+	struct choice *best = &choices[0];
+	struct choice *chosen;
+
+	const bool explore = choices_len == 0 || kr_rand_coin(EPSILON_NOMIN, EPSILON_DENOM);
+	if (explore) {
+		/* "EXPLORE":
+		 * randomly choose some option
+		 * (including resolution of some new name). */
+		int index = kr_rand_bytes(1) % (choices_len + unresolved_len);
+		if (index < unresolved_len) {
+			// We will resolve a new NS name
+			*transport = (struct kr_transport){
+				.protocol = unresolved[index].type,
+				.ns_name = unresolved[index].name
+			};
+			return transport;
+		} else {
+			chosen = &choices[index - unresolved_len];
+		}
+	} else {
+		/* "EXPLOIT":
+		 * choose a resolved address which seems best right now. */
+		chosen = best;
+		if (no6_is_bad())
+			VERBOSE_MSG(NULL, "NO6: is KO [exploit]\n");
+	}
+
+	/* Don't try the same server again when there are other choices to be explored */
+	if (chosen->address_state->error_count && unresolved_len) {
+		int index = kr_rand_bytes(1) % unresolved_len;
+		*transport = (struct kr_transport){
+			.ns_name = unresolved[index].name,
+			.protocol = unresolved[index].type,
+		};
+		return transport;
+	}
+
+	unsigned timeout;
+	if (no_rtt_info(chosen->address_state->rtt_state)) {
+		/* Exponential back-off when retrying after timeout and choosing
+		 * an unknown server. */
+		timeout = back_off_timeout(DEFAULT_TIMEOUT, timeouts);
+	} else {
+		timeout = calc_timeout(chosen->address_state->rtt_state);
+		if (explore) {
+			/* When trying a random server, we cap the timeout to EXPLORE_TIMEOUT_COEFFICIENT
+			 * times the timeout for the best server. This is done so we don't spend
+			 * unreasonable amounts of time probing really bad servers while still
+			 * checking once in a while for e.g. big network change etc.
+			 * We also note this capping was done and don't punish the bad server
+			 * further if it fails to answer in the capped timeout. */
+			unsigned best_timeout = calc_timeout(best->address_state->rtt_state);
+			if (timeout > best_timeout * EXPLORE_TIMEOUT_COEFFICIENT) {
+				timeout = best_timeout * EXPLORE_TIMEOUT_COEFFICIENT;
+				transport->timeout_capped = true;
+			}
+		}
+	}
+
+	enum kr_transport_protocol protocol;
+	if (chosen->address_state->tls_capable) {
+		protocol = KR_TRANSPORT_TLS;
+	} else if (tcp ||
+		   chosen->address_state->errors[KR_SELECTION_QUERY_TIMEOUT] >= TCP_TIMEOUT_THRESHOLD ||
+		   timeout > TCP_RTT_THRESHOLD) {
+		protocol = KR_TRANSPORT_TCP;
+	} else {
+		protocol = KR_TRANSPORT_UDP;
+	}
+
+	*transport = (struct kr_transport){
+		.ns_name = chosen->address_state->ns_name,
+		.protocol = protocol,
+		.timeout = timeout,
+	};
+
+	int port = chosen->port;
+	if (!port) {
+		switch (transport->protocol) {
+		case KR_TRANSPORT_TLS:
+			port = KR_DNS_TLS_PORT;
+			break;
+		case KR_TRANSPORT_UDP:
+		case KR_TRANSPORT_TCP:
+			port = KR_DNS_PORT;
+			break;
+		default:
+			assert(0);
+			return NULL;
+		}
+	}
+
+	switch (chosen->address_len)
+	{
+	case sizeof(struct in_addr):
+		transport->address.ip4 = chosen->address.ip4;
+		transport->address.ip4.sin_port = htons(port);
+		break;
+	case sizeof(struct in6_addr):
+		transport->address.ip6 = chosen->address.ip6;
+		transport->address.ip6.sin6_port = htons(port);
+		break;
+	default:
+		assert(0);
+		return NULL;
+	}
+
+	transport->address_len = chosen->address_len;
+
+	if (choice_index) {
+		*choice_index = chosen->address_state->choice_array_index;
+	}
+
+	return transport;
+}
+
+void update_rtt(struct kr_query *qry, struct address_state *addr_state,
+		const struct kr_transport *transport, unsigned rtt)
+{
+	if (!transport || !addr_state) {
+		/* Answers from cache have NULL transport, ignore them. */
+		return;
+	}
+
+	struct kr_cache *cache = &qry->request->ctx->cache;
+
+	uint8_t *address = ip_to_bytes(&transport->address, transport->address_len);
+	/* This construct is a bit racy since the global state may change
+	 * between calls to `get_rtt_state` and `put_rtt_state`  but we don't
+	 * care that much since it is rare and we only risk slightly suboptimal
+	 * transport choice. */
+	struct rtt_state cur_rtt_state =
+		get_rtt_state(address, transport->address_len, cache);
+	struct rtt_state new_rtt_state = calc_rtt_state(cur_rtt_state, rtt);
+	put_rtt_state(address, transport->address_len, new_rtt_state, cache);
+
+	if (transport->address_len == sizeof(struct in6_addr))
+		no6_success(qry);
+
+	WITH_VERBOSE(qry)
+	{
+	KR_DNAME_GET_STR(ns_name, transport->ns_name);
+	KR_DNAME_GET_STR(zonecut_str, qry->zone_cut.name);
+	const char *ns_str = kr_straddr(&transport->address.ip);
+
+	VERBOSE_MSG(
+		qry,
+		"=> id: '%05u' updating: '%s'@'%s' zone cut: '%s'"
+		" with rtt %u to srtt: %d and variance: %d \n",
+		qry->id, ns_name, ns_str ? ns_str : "", zonecut_str,
+		rtt, new_rtt_state.srtt, new_rtt_state.variance);
+	}
+}
+
+static void cache_timeout(const struct kr_query *qry, const struct kr_transport *transport,
+			  struct address_state *addr_state, struct kr_cache *cache)
+{
+	if (transport->deduplicated) {
+		/* Transport was chosen by a different query, that one will
+		 * cache the result. */
+		return;
+	}
+
+	uint8_t *address = ip_to_bytes(&transport->address, transport->address_len);
+	if (transport->address_len == sizeof(struct in6_addr))
+		no6_timeouted(qry, address);
+
+	struct rtt_state old_state = addr_state->rtt_state;
+	struct rtt_state cur_state =
+		get_rtt_state(address, transport->address_len, cache);
+
+	/* We could lose some update from some other process by doing this,
+	 * but at least timeout count can't blow up. */
+	if (cur_state.consecutive_timeouts == old_state.consecutive_timeouts) {
+		if (++cur_state.consecutive_timeouts >=
+		    KR_NS_TIMEOUT_ROW_DEAD) {
+			cur_state.dead_since = kr_now();
+		}
+		put_rtt_state(address, transport->address_len, cur_state, cache);
+	} else {
+		/* `get_rtt_state` opens a cache transaction, we have to end it. */
+		kr_cache_commit(cache);
+	}
+}
+
+void error(struct kr_query *qry, struct address_state *addr_state,
+	   const struct kr_transport *transport,
+	   enum kr_selection_error sel_error)
+{
+	if (!transport || !addr_state) {
+		/* Answers from cache have NULL transport, ignore them. */
+		return;
+	}
+
+	switch (sel_error) {
+	case KR_SELECTION_OK:
+		return;
+	case KR_SELECTION_TCP_CONNECT_FAILED:
+	case KR_SELECTION_TCP_CONNECT_TIMEOUT:
+		qry->server_selection.local_state->force_udp = true;
+		qry->flags.NO_0X20 = false;
+		/* Connection and handshake failures have properties similar
+		 * to UDP timeouts, so we handle them (almost) the same way. */
+		/* fall-through */
+	case KR_SELECTION_TLS_HANDSHAKE_FAILED:
+	case KR_SELECTION_QUERY_TIMEOUT:
+		qry->server_selection.local_state->timeouts++;
+		/* Make sure that the query was chosen by this query and timeout wasn't capped
+		 * (see kr_transport::timeout_capped for details). */
+		if (!transport->deduplicated && !transport->timeout_capped) {
+			cache_timeout(qry, transport, addr_state,
+				      &qry->request->ctx->cache);
+		}
+		break;
+	case KR_SELECTION_FORMERR:
+		if (qry->flags.NO_EDNS) {
+			addr_state->broken = true;
+		} else {
+			qry->flags.NO_EDNS = true;
+		}
+		break;
+	case KR_SELECTION_FORMERR_EDNS:
+		addr_state->broken = true;
+		break;
+	case KR_SELECTION_MISMATCHED:
+		if (qry->flags.NO_0X20 && qry->flags.TCP) {
+			addr_state->broken = true;
+		} else {
+			qry->flags.TCP = true;
+			qry->flags.NO_0X20 = true;
+		}
+		break;
+	case KR_SELECTION_TRUNCATED:
+		if (transport->protocol == KR_TRANSPORT_UDP) {
+			qry->server_selection.local_state->truncated = true;
+			/* TC=1 over UDP is not an error, so we compensate. */
+			addr_state->error_count--;
+		} else {
+			addr_state->broken = true;
+		}
+		break;
+	case KR_SELECTION_REFUSED:
+	case KR_SELECTION_SERVFAIL:
+		if (qry->flags.NO_MINIMIZE && qry->flags.NO_0X20 && qry->flags.TCP) {
+			addr_state->broken = true;
+		} else if (qry->flags.NO_MINIMIZE) {
+			qry->flags.NO_0X20 = true;
+			qry->flags.TCP = true;
+		} else {
+			qry->flags.NO_MINIMIZE = true;
+		}
+		break;
+	case KR_SELECTION_LAME_DELEGATION:
+		if (qry->flags.NO_MINIMIZE) {
+			/* Lame delegations are weird, they breed more lame delegations on broken
+			* zones since trying another server from the same set usualy doesn't help.
+			* We force resolution of another NS name in hope of getting somewhere. */
+			qry->server_selection.local_state->force_resolve = true;
+			addr_state->broken = true;
+		} else {
+			qry->flags.NO_MINIMIZE = true;
+		}
+		break;
+	case KR_SELECTION_NOTIMPL:
+	case KR_SELECTION_OTHER_RCODE:
+	case KR_SELECTION_DNSSEC_ERROR:
+	case KR_SELECTION_BAD_CNAME:
+	case KR_SELECTION_MALFORMED:
+		/* These errors are fatal, no point in trying this server again. */
+		addr_state->broken = true;
+		break;
+	default:
+		assert(0);
+		break;
+	}
+
+	addr_state->error_count++;
+	addr_state->errors[sel_error]++;
+
+	WITH_VERBOSE(qry)
+	{
+	KR_DNAME_GET_STR(ns_name, transport->ns_name);
+	KR_DNAME_GET_STR(zonecut_str, qry->zone_cut.name);
+	const char *ns_str = kr_straddr(&transport->address.ip);
+	const char *err_str = kr_selection_error_str(sel_error);
+
+	VERBOSE_MSG(
+		qry,
+		"=> id: '%05u' noting selection error: '%s'@'%s' zone cut: '%s' error: %d %s\n",
+		qry->id, ns_name, ns_str ? ns_str : "", zonecut_str,
+		sel_error, err_str ? err_str : "??");
+	}
+}
+
+void kr_server_selection_init(struct kr_query *qry)
+{
+	struct knot_mm *mempool = &qry->request->pool;
+	struct local_state *local_state = mm_calloc(mempool, 1, sizeof(*local_state));
+
+	if (qry->flags.FORWARD || qry->flags.STUB) {
+		qry->server_selection = (struct kr_server_selection){
+			.initialized = true,
+			.choose_transport = forward_choose_transport,
+			.update_rtt = forward_update_rtt,
+			.error = forward_error,
+			.local_state = local_state,
+		};
+		forward_local_state_alloc(
+			mempool, &qry->server_selection.local_state->private,
+			qry->request);
+	} else {
+		qry->server_selection = (struct kr_server_selection){
+			.initialized = true,
+			.choose_transport = iter_choose_transport,
+			.update_rtt = iter_update_rtt,
+			.error = iter_error,
+			.local_state = local_state,
+		};
+		iter_local_state_alloc(
+			mempool, &qry->server_selection.local_state->private);
+	}
+}
+
+int kr_forward_add_target(struct kr_request *req, const struct sockaddr *sock)
+{
+	if (!req->selection_context.forwarding_targets.at) {
+		return kr_error(EINVAL);
+	}
+
+	union inaddr address;
+
+	switch (sock->sa_family) {
+	case AF_INET:
+		if (req->options.NO_IPV4)
+			return kr_error(EINVAL);
+		address.ip4 = *(const struct sockaddr_in *)sock;
+		break;
+	case AF_INET6:
+		if (req->options.NO_IPV6)
+			return kr_error(EINVAL);
+		address.ip6 = *(const struct sockaddr_in6 *)sock;
+		break;
+	default:
+		return kr_error(EINVAL);
+	}
+
+	array_push_mm(req->selection_context.forwarding_targets, address,
+		      kr_memreserve, &req->pool);
+	return kr_ok();
+}
diff --git a/lib/selection.h b/lib/selection.h
new file mode 100644
index 0000000..02ef5b5
--- /dev/null
+++ b/lib/selection.h
@@ -0,0 +1,259 @@
+/*  Copyright (C) 2014-2020 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#pragma once
+
+/**
+ * @file selection.h
+ * Provides server selection API (see `kr_server_selection`)
+ * and functions common to both implementations.
+ */
+
+#include "lib/cache/api.h"
+
+/* After KR_NS_TIMEOUT_ROW_DEAD consecutive timeouts, we consider the upstream IP dead for KR_NS_TIMEOUT_RETRY_INTERVAL ms */
+#define KR_NS_TIMEOUT_ROW_DEAD 4
+#define KR_NS_TIMEOUT_RETRY_INTERVAL 1000
+
+/**
+ * These errors are to be reported as feedback to server selection.
+ * See `kr_server_selection::error` for more details.
+ */
+enum kr_selection_error {
+	KR_SELECTION_OK = 0,
+
+	// Network errors
+	KR_SELECTION_QUERY_TIMEOUT,
+	KR_SELECTION_TLS_HANDSHAKE_FAILED,
+	KR_SELECTION_TCP_CONNECT_FAILED,
+	KR_SELECTION_TCP_CONNECT_TIMEOUT,
+
+	// RCODEs
+	KR_SELECTION_REFUSED,
+	KR_SELECTION_SERVFAIL,
+	KR_SELECTION_FORMERR,      /// inside an answer without an OPT record
+	KR_SELECTION_FORMERR_EDNS, /// with an OPT record
+	KR_SELECTION_NOTIMPL,
+	KR_SELECTION_OTHER_RCODE,
+
+	// DNS errors
+	KR_SELECTION_MALFORMED,
+	/** Name or type mismatch. */
+	KR_SELECTION_MISMATCHED,
+	KR_SELECTION_TRUNCATED,
+	KR_SELECTION_DNSSEC_ERROR,
+	KR_SELECTION_LAME_DELEGATION,
+	/** Too long chain, or a cycle. */
+	KR_SELECTION_BAD_CNAME,
+
+	/** Leave this last, as it is used as array size. */
+	KR_SELECTION_NUMBER_OF_ERRORS
+};
+
+enum kr_transport_protocol {
+	/** Selected name with no IPv4 address, it has to be resolved first. */
+	KR_TRANSPORT_RESOLVE_A,
+	/** Selected name with no IPv6 address, it has to be resolved first. */
+	KR_TRANSPORT_RESOLVE_AAAA,
+	KR_TRANSPORT_UDP,
+	KR_TRANSPORT_TCP,
+	KR_TRANSPORT_TLS,
+};
+
+/**
+ * Output of the selection algorithm.
+ */
+struct kr_transport {
+	knot_dname_t *ns_name; /**< Set to "." for forwarding targets.*/
+	union inaddr address;
+	size_t address_len;
+	enum kr_transport_protocol protocol;
+	unsigned timeout; /**< Timeout in ms to be set for UDP transmission. */
+	/** Timeout was capped to a maximum value based on the other candidates
+	 * when choosing this transport. The timeout therefore can be much lower
+	 * than what we expect it to be. We basically probe the server for a sudden
+	 * network change but we expect it to timeout in most cases. We have to keep
+	 * this in mind when noting the timeout in cache. */
+	bool timeout_capped;
+	/** True iff transport was set in worker.c:subreq_finalize,
+	 * that means it may be different from the one originally chosen one.*/
+	bool deduplicated;
+};
+
+struct local_state {
+	int timeouts; /**< Number of timeouts that occured resolving this query.*/
+	bool truncated; /**< Query was truncated, switch to TCP. */
+	/** Force resolution of a new NS name (if possible)
+	 * Done by selection.c:error in some cases. */
+	bool force_resolve;
+	/** Used to work around auths with broken TCP. */
+	bool force_udp;
+	void *private; /**< Inner state of the implementation.*/
+};
+
+/**
+ * Specifies a API for selecting transports and giving feedback on the choices.
+ *
+ * The function pointers are to be used throughout resolver when some information about
+ * the transport is obtained. E.g. RTT in `worker.c` or RCODE in `iterate.c`,…
+ */
+struct kr_server_selection {
+	bool initialized;
+	/**
+	 * Puts a pointer to next transport of @p qry to @p transport .
+	 *
+	 * Allocates new kr_transport in request's mempool, chooses transport to be used for this query.
+	 * Selection may fail, so @p transport can be set to NULL.
+	 *
+	 * @param transport to be filled with pointer to the chosen transport or NULL on failure
+	 */
+	void (*choose_transport)(struct kr_query *qry,
+				 struct kr_transport **transport);
+	/** Report back the RTT of network operation for transport in ms. */
+	void (*update_rtt)(struct kr_query *qry,
+			   const struct kr_transport *transport, unsigned rtt);
+	/** Report back error encourtered with the chosen transport. See `enum kr_selection` */
+	void (*error)(struct kr_query *qry,
+		      const struct kr_transport *transport,
+		      enum kr_selection_error error);
+
+	struct local_state *local_state;
+};
+
+/**
+ * @brief Initialize the server selection API for @p qry.
+ *
+ * The implementation is to be chosen based on qry->flags.
+ */
+KR_EXPORT
+void kr_server_selection_init(struct kr_query *qry);
+
+/**
+ * @brief Add forwarding target to request.
+ *
+ * This is exposed to Lua in order to add forwarding targets to request.
+ * These are then shared by all the queries in said request.
+ */
+KR_EXPORT
+int kr_forward_add_target(struct kr_request *req, const struct sockaddr *sock);
+
+
+
+
+
+/* Below are internal parts shared by ./selection_{forward,iter}.c */
+
+/**
+ * To be held per IP address in the global LMDB cache
+ */
+struct rtt_state {
+	int32_t srtt; /**< Smoothed RTT, i.e. an estimate of round-trip time. */
+	int32_t variance; /**< An estimate of RTT's standard derivation (not variance). */
+	/** Note: some TCP and TLS failures are also considered as timeouts. */
+	int32_t consecutive_timeouts;
+	/** Timestamp of pronouncing this IP bad based on KR_NS_TIMEOUT_ROW_DEAD */
+	uint64_t dead_since;
+};
+
+/**
+ * @brief To be held per IP address and locally "inside" query.
+ */
+struct address_state {
+	/** Used to distinguish old and valid records in local_state; -1 means unusable IP. */
+	unsigned int generation;
+	struct rtt_state rtt_state;
+	knot_dname_t *ns_name;
+	bool tls_capable : 1;
+	/* TODO: uncomment these once we actually use this information in selection
+	bool tcp_waiting : 1;
+	bool tcp_connected : 1;
+	*/
+	int choice_array_index;
+	int error_count;
+	bool broken;
+	int errors[KR_SELECTION_NUMBER_OF_ERRORS];
+};
+
+/**
+ * @brief Array of these is one of inputs for the actual selection algorithm (`select_transport`)
+ */
+struct choice {
+	union inaddr address;
+	size_t address_len;
+	struct address_state *address_state;
+	/** used to overwrite the port number;
+	 * if zero, `select_transport` determines it. */
+	uint16_t port;
+};
+
+/**
+ * @brief Array of these is description of names to be resolved (i.e. name without some address)
+ */
+struct to_resolve {
+	knot_dname_t *name;
+	/** Either KR_TRANSPORT_RESOLVE_A or KR_TRANSPORT_RESOLVE_AAAA is valid here. */
+	enum kr_transport_protocol type;
+};
+
+/**
+ * @brief Based on passed choices, choose the next transport.
+ *
+ * Common function to both implementations (iteration and forwarding).
+ * The `*_choose_transport` functions from `selection_*.h` preprocess the input for this one.
+ *
+ * @param choices Options to choose from, see struct above
+ * @param unresolved Array of names that can be resolved (i.e. no A/AAAA record)
+ * @param timeouts Number of timeouts that occured in this query (used for exponential backoff)
+ * @param mempool Memory context of current request
+ * @param tcp Force TCP as transport protocol
+ * @param[out] choice_index Optionally index of the chosen transport in the @p choices array.
+ * @return Chosen transport (on mempool) or NULL when no choice is viable
+ */
+struct kr_transport *select_transport(struct choice choices[], int choices_len,
+				      struct to_resolve unresolved[],
+				      int unresolved_len, int timeouts,
+				      struct knot_mm *mempool, bool tcp,
+				      size_t *choice_index);
+
+/**
+ * Common part of RTT feedback mechanism. Notes RTT to global cache.
+ */
+void update_rtt(struct kr_query *qry, struct address_state *addr_state,
+		const struct kr_transport *transport, unsigned rtt);
+
+/**
+ * Common part of error feedback mechanism.
+ */
+void error(struct kr_query *qry, struct address_state *addr_state,
+	   const struct kr_transport *transport,
+	   enum kr_selection_error sel_error);
+
+/**
+ * Get RTT state from cache. Returns `default_rtt_state` on unknown addresses.
+ *
+ * Note that this opens a cache transaction which is usually closed by calling
+ * `put_rtt_state`, i.e. callee is responsible for its closing
+ * (e.g. calling kr_cache_commit).
+ */
+struct rtt_state get_rtt_state(const uint8_t *ip, size_t len,
+			       struct kr_cache *cache);
+
+int put_rtt_state(const uint8_t *ip, size_t len, struct rtt_state state,
+		  struct kr_cache *cache);
+
+/**
+ * @internal Helper function for conversion between different IP representations.
+ */
+void bytes_to_ip(uint8_t *bytes, size_t len, uint16_t port, union inaddr *dst);
+
+/**
+ * @internal Helper function for conversion between different IP representations.
+ */
+uint8_t *ip_to_bytes(const union inaddr *src, size_t len);
+
+/**
+ * @internal Fetch per-address information from various sources.
+ */
+void update_address_state(struct address_state *state, union inaddr *address,
+			  size_t address_len, struct kr_query *qry);
diff --git a/lib/selection_forward.c b/lib/selection_forward.c
new file mode 100644
index 0000000..da17bcf
--- /dev/null
+++ b/lib/selection_forward.c
@@ -0,0 +1,129 @@
+/*  Copyright (C) 2014-2020 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#include "lib/selection_forward.h"
+#include "lib/resolve.h"
+
+#define VERBOSE_MSG(qry, ...) QRVERBOSE((qry), "slct", __VA_ARGS__)
+
+#define FORWARDING_TIMEOUT 2000
+
+struct forward_local_state {
+	inaddr_array_t *targets;
+	struct address_state *addr_states;
+	/** Index of last choice in the targets array, used for error reporting. */
+	size_t last_choice_index;
+};
+
+void forward_local_state_alloc(struct knot_mm *mm, void **local_state,
+			       struct kr_request *req)
+{
+	assert(req->selection_context.forwarding_targets.at);
+	*local_state = mm_calloc(mm, 1, sizeof(struct forward_local_state));
+
+	struct forward_local_state *forward_state = *local_state;
+	forward_state->targets = &req->selection_context.forwarding_targets;
+
+	forward_state->addr_states = mm_calloc(mm, forward_state->targets->len,
+						sizeof(struct address_state));
+}
+
+void forward_choose_transport(struct kr_query *qry,
+			      struct kr_transport **transport)
+{
+	struct forward_local_state *local_state =
+		qry->server_selection.local_state->private;
+	struct choice choices[local_state->targets->len];
+	int valid = 0;
+
+	for (int i = 0; i < local_state->targets->len; i++) {
+		union inaddr *address = &local_state->targets->at[i];
+		size_t addr_len;
+		uint16_t port;
+		switch (address->ip.sa_family) {
+		case AF_INET:
+			port = ntohs(address->ip4.sin_port);
+			addr_len = sizeof(struct in_addr);
+			break;
+		case AF_INET6:
+			port = ntohs(address->ip6.sin6_port);
+			addr_len = sizeof(struct in6_addr);
+			break;
+		default:
+			assert(0);
+			*transport = NULL;
+			return;
+		}
+
+		struct address_state *addr_state = &local_state->addr_states[i];
+		addr_state->ns_name = (knot_dname_t *)"";
+
+		update_address_state(addr_state, address, addr_len, qry);
+
+		if (addr_state->generation == -1) {
+			continue;
+		}
+		addr_state->choice_array_index = i;
+
+		choices[valid++] = (struct choice){
+			.address = *address,
+			.address_len = addr_len,
+			.address_state = addr_state,
+			.port = port,
+		};
+	}
+
+	bool tcp = qry->flags.TCP || qry->server_selection.local_state->truncated;
+	*transport =
+		select_transport(choices, valid, NULL, 0,
+				 qry->server_selection.local_state->timeouts,
+				 &qry->request->pool, tcp,
+				 &local_state->last_choice_index);
+	if (*transport) {
+		/* Set static timeout for forwarding; there is no point in this
+		 * being dynamic since the RTT of a packet to forwarding target
+		 * says nothing about the network RTT of said target, since
+		 * it is doing resolution upstream. */
+		(*transport)->timeout = FORWARDING_TIMEOUT;
+		/* Try to avoid TCP in STUB case.  It seems better for common use cases. */
+		if (qry->flags.STUB && !tcp && (*transport)->protocol == KR_TRANSPORT_TCP)
+			(*transport)->protocol = KR_TRANSPORT_UDP;
+		/* We need to propagate this to flags since it's used in other
+		 * parts of the resolver (e.g. logging and stats). */
+		qry->flags.TCP = (*transport)->protocol == KR_TRANSPORT_TCP
+			      || (*transport)->protocol == KR_TRANSPORT_TLS;
+	}
+}
+
+void forward_error(struct kr_query *qry, const struct kr_transport *transport,
+		   enum kr_selection_error sel_error)
+{
+	if (!qry->server_selection.initialized) {
+		return;
+	}
+	struct forward_local_state *local_state =
+		qry->server_selection.local_state->private;
+	struct address_state *addr_state =
+		&local_state->addr_states[local_state->last_choice_index];
+	error(qry, addr_state, transport, sel_error);
+}
+
+void forward_update_rtt(struct kr_query *qry,
+			const struct kr_transport *transport, unsigned rtt)
+{
+	if (!qry->server_selection.initialized) {
+		return;
+	}
+
+	if (!transport) {
+		return;
+	}
+
+	struct forward_local_state *local_state =
+		qry->server_selection.local_state->private;
+	struct address_state *addr_state =
+		&local_state->addr_states[local_state->last_choice_index];
+
+	update_rtt(qry, addr_state, transport, rtt);
+}
diff --git a/lib/selection_forward.h b/lib/selection_forward.h
new file mode 100644
index 0000000..e66274f
--- /dev/null
+++ b/lib/selection_forward.h
@@ -0,0 +1,17 @@
+/*  Copyright (C) 2014-2020 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#pragma once
+
+#include "lib/selection.h"
+#include "lib/resolve.h"
+
+void forward_local_state_alloc(struct knot_mm *mm, void **local_state,
+			       struct kr_request *req);
+void forward_choose_transport(struct kr_query *qry,
+			      struct kr_transport **transport);
+void forward_error(struct kr_query *qry, const struct kr_transport *transport,
+		   enum kr_selection_error sel_error);
+void forward_update_rtt(struct kr_query *qry,
+			const struct kr_transport *transport, unsigned rtt);
\ No newline at end of file
diff --git a/lib/selection_iter.c b/lib/selection_iter.c
new file mode 100644
index 0000000..32d5a86
--- /dev/null
+++ b/lib/selection_iter.c
@@ -0,0 +1,358 @@
+/*  Copyright (C) 2014-2020 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#include "lib/selection_iter.h"
+#include "lib/selection.h"
+
+#include "lib/generic/trie.h"
+#include "lib/generic/pack.h"
+#include "lib/zonecut.h"
+#include "lib/resolve.h"
+
+#define VERBOSE_MSG(qry, ...) QRVERBOSE((qry), "slct", __VA_ARGS__)
+
+/// To be held per query and locally.  Allocations are in the kr_request's mempool.
+struct iter_local_state {
+	trie_t *names; /// knot_dname_t -> struct iter_name_state *
+	trie_t *addresses; /// IP address -> struct address_state *
+	knot_dname_t *zonecut;
+	/** Used to distinguish old and valid records in tries. */
+	unsigned int generation;
+	enum kr_selection_error last_error;
+	unsigned int no_ns_addr_count;
+};
+
+enum record_state { RECORD_UNKNOWN, RECORD_RESOLVED, RECORD_TRIED };
+
+// To be held per NS name and locally
+struct iter_name_state {
+	unsigned int generation;
+	enum record_state a_state;
+	enum record_state aaaa_state;
+};
+
+void iter_local_state_alloc(struct knot_mm *mm, void **local_state)
+{
+	*local_state = mm_calloc(mm, 1, sizeof(struct iter_local_state));
+}
+
+static struct address_state *get_address_state(struct iter_local_state *local_state,
+						const struct kr_transport *transport)
+{
+	if (!transport) {
+		return NULL;
+	}
+
+	uint8_t *address = ip_to_bytes(&transport->address, transport->address_len);
+	trie_val_t *address_state = trie_get_try(local_state->addresses, (char *)address,
+						 transport->address_len);
+	if (!address_state) {
+		assert(transport->deduplicated);
+		/* Transport was chosen by a different query. */
+		return NULL;
+	}
+	return *address_state;
+}
+
+static void unpack_state_from_zonecut(struct iter_local_state *local_state,
+				      struct kr_query *qry)
+{
+	struct kr_zonecut *zonecut = &qry->zone_cut;
+	struct knot_mm *mm = &qry->request->pool;
+
+	bool zcut_changed = false;
+	if (local_state->names == NULL || local_state->addresses == NULL) {
+		/* Local state initialization. */
+		memset(local_state, 0, sizeof(struct iter_local_state));
+		local_state->names = trie_create(mm);
+		local_state->addresses = trie_create(mm);
+	} else {
+		zcut_changed = !knot_dname_is_equal(zonecut->name, local_state->zonecut);
+	}
+	local_state->zonecut = zonecut->name;
+	local_state->generation++;
+
+	if (zcut_changed) {
+		local_state->no_ns_addr_count = 0;
+	}
+
+	trie_it_t *it;
+	const unsigned int current_generation = local_state->generation;
+
+	for (it = trie_it_begin(zonecut->nsset); !trie_it_finished(it); trie_it_next(it)) {
+		knot_dname_t *dname = (knot_dname_t *)trie_it_key(it, NULL);
+		pack_t *addresses = *trie_it_val(it);
+
+		trie_val_t *val = trie_get_ins(local_state->names, (char *)dname,
+					       knot_dname_size(dname));
+		if (!*val) {
+			/* We encountered this name for the first time. */
+			*val = mm_calloc(mm, 1, sizeof(struct iter_name_state));
+		}
+		struct iter_name_state *name_state = *val;
+		name_state->generation = current_generation;
+
+		if (zcut_changed) {
+			/* Set name as unresolved as they might have fallen out
+			 * of cache (TTL expired). */
+			name_state->a_state = RECORD_UNKNOWN;
+			name_state->aaaa_state = RECORD_UNKNOWN;
+		}
+
+		/* Iterate over all addresses of this NS (if any). */
+		for (uint8_t *obj = pack_head(*addresses); obj != pack_tail(*addresses);
+		     obj = pack_obj_next(obj)) {
+			uint8_t *address = pack_obj_val(obj);
+			size_t address_len = pack_obj_len(obj);
+			trie_val_t *tval = trie_get_ins(local_state->addresses,
+							(char *)address,
+							address_len);
+			if (!*tval) {
+				/* We have have not seen this address before. */
+				*tval = mm_calloc(mm, 1, sizeof(struct address_state));
+			}
+			struct address_state *address_state = *tval;
+			address_state->generation = current_generation;
+			address_state->ns_name = dname;
+
+			if (address_len == sizeof(struct in_addr)) {
+				name_state->a_state = RECORD_RESOLVED;
+			} else if (address_len == sizeof(struct in6_addr)) {
+				name_state->aaaa_state = RECORD_RESOLVED;
+			}
+			union inaddr tmp_address;
+			bytes_to_ip(address, address_len, 0, &tmp_address);
+			update_address_state(address_state, &tmp_address, address_len, qry);
+		}
+	}
+	trie_it_free(it);
+}
+
+static int get_valid_addresses(struct iter_local_state *local_state,
+				struct choice choices[])
+{
+	unsigned count = 0;
+	trie_it_t *it;
+	for (it = trie_it_begin(local_state->addresses); !trie_it_finished(it);
+	     trie_it_next(it)) {
+		size_t address_len;
+		uint8_t *address = (uint8_t *)trie_it_key(it, &address_len);
+		struct address_state *address_state = *trie_it_val(it);
+		if (address_state->generation == local_state->generation &&
+		    !address_state->broken) {
+			choices[count] = (struct choice){
+				.address_len = address_len,
+				.address_state = address_state,
+			};
+			bytes_to_ip(address, address_len, 0, &choices[count].address);
+			count++;
+		}
+	}
+	trie_it_free(it);
+	return count;
+}
+
+static int get_resolvable_names(struct iter_local_state *local_state,
+				struct to_resolve resolvable[], struct kr_query *qry)
+{
+	/* Further resolution is not possible until we get `. DNSKEY` record;
+	 * we have to choose one of the known addresses here. */
+	if (qry->sname[0] == '\0' && qry->stype == KNOT_RRTYPE_DNSKEY) {
+		return 0;
+	}
+
+	unsigned count = 0;
+	trie_it_t *it;
+	for (it = trie_it_begin(local_state->names); !trie_it_finished(it);
+	     trie_it_next(it)) {
+		struct iter_name_state *name_state = *trie_it_val(it);
+		if (name_state->generation != local_state->generation)
+			continue;
+
+		knot_dname_t *name = (knot_dname_t *)trie_it_key(it, NULL);
+		if (qry->stype == KNOT_RRTYPE_DNSKEY &&
+		    knot_dname_in_bailiwick(name, qry->sname) > 0) {
+			/* Resolving `domain. DNSKEY` can't trigger the
+			 * resolution of `sub.domain. A/AAAA` since it
+			 * will cause a cycle. */
+			continue;
+		}
+
+		/* FIXME: kr_rplan_satisfies(qry,…) should have been here, but this leads to failures on
+		 * iter_ns_badip.rpl, this is because the test requires the resolver to switch to parent
+		 * side after a record in cache expires. Only way to do this in the current zonecut setup is
+		 * to requery the same query twice in the row. So we have to allow that and only check the
+		 * rplan from parent upwards.
+		 */
+		bool a_in_rplan = kr_rplan_satisfies(qry->parent, name,
+						     KNOT_CLASS_IN, KNOT_RRTYPE_A);
+		bool aaaa_in_rplan = kr_rplan_satisfies(qry->parent, name,
+							KNOT_CLASS_IN, KNOT_RRTYPE_AAAA);
+
+		if (name_state->a_state == RECORD_UNKNOWN &&
+		    !qry->flags.NO_IPV4 && !a_in_rplan) {
+			resolvable[count++] = (struct to_resolve){
+				name, KR_TRANSPORT_RESOLVE_A
+			};
+		}
+
+		if (name_state->aaaa_state == RECORD_UNKNOWN &&
+		    !qry->flags.NO_IPV6 && !aaaa_in_rplan) {
+			resolvable[count++] = (struct to_resolve){
+				name, KR_TRANSPORT_RESOLVE_AAAA
+			};
+		}
+	}
+	trie_it_free(it);
+	return count;
+}
+
+static void update_name_state(knot_dname_t *name, enum kr_transport_protocol type,
+			      trie_t *names)
+{
+	size_t name_len = knot_dname_size(name);
+	trie_val_t *val = trie_get_try(names, (char *)name, name_len);
+
+	if (!val) {
+		return;
+	}
+
+	struct iter_name_state *name_state = (struct iter_name_state *)*val;
+	switch (type) {
+	case KR_TRANSPORT_RESOLVE_A:
+		name_state->a_state = RECORD_TRIED;
+		break;
+	case KR_TRANSPORT_RESOLVE_AAAA:
+		name_state->aaaa_state = RECORD_TRIED;
+		break;
+	default:
+		assert(0);
+	}
+}
+
+void iter_choose_transport(struct kr_query *qry, struct kr_transport **transport)
+{
+	struct knot_mm *mempool = &qry->request->pool;
+	struct iter_local_state *local_state =
+		(struct iter_local_state *)
+			qry->server_selection.local_state->private;
+
+	unpack_state_from_zonecut(local_state, qry);
+
+	struct choice choices[trie_weight(local_state->addresses)];
+	/* We may try to resolve A and AAAA record for each name, so therefore
+	 * 2*trie_weight(…) is here. */
+	struct to_resolve resolvable[2 * trie_weight(local_state->names)];
+
+	// Filter valid addresses and names from the tries
+	int choices_len = get_valid_addresses(local_state, choices);
+	int resolvable_len = get_resolvable_names(local_state, resolvable, qry);
+
+	if (qry->server_selection.local_state->force_resolve && resolvable_len) {
+		choices_len = 0;
+		qry->server_selection.local_state->force_resolve = false;
+	}
+
+	bool tcp = qry->flags.TCP || qry->server_selection.local_state->truncated;
+	*transport = select_transport(choices, choices_len, resolvable, resolvable_len,
+				      qry->server_selection.local_state->timeouts,
+				      mempool, tcp, NULL);
+	bool nxnsattack_mitigation = false;
+
+	if (*transport) {
+		switch ((*transport)->protocol) {
+		case KR_TRANSPORT_RESOLVE_A:
+		case KR_TRANSPORT_RESOLVE_AAAA:
+			if (++local_state->no_ns_addr_count > KR_COUNT_NO_NSADDR_LIMIT) {
+				*transport = NULL;
+				nxnsattack_mitigation = true;
+				break;
+			}
+			/* Note that we tried resolving this name to not try it again. */
+			update_name_state((*transport)->ns_name, (*transport)->protocol, local_state->names);
+			break;
+		case KR_TRANSPORT_TLS:
+		case KR_TRANSPORT_TCP:
+			/* We need to propagate this to flags since it's used in
+			 * other parts of the resolver. */
+			qry->flags.TCP = true;
+		case KR_TRANSPORT_UDP: /* fall through */
+			local_state->no_ns_addr_count = 0;
+			break;
+		default:
+			assert(0);
+			break;
+		}
+
+		if (*transport &&
+		    (*transport)->protocol == KR_TRANSPORT_TCP &&
+		    !qry->server_selection.local_state->truncated &&
+		    qry->server_selection.local_state->force_udp) {
+			// Last chance on broken TCP.
+			(*transport)->protocol = KR_TRANSPORT_UDP;
+			qry->flags.TCP = false;
+		}
+	}
+
+	if (*transport == NULL && local_state->last_error == KR_SELECTION_DNSSEC_ERROR) {
+		/* Last selected server had broken DNSSEC and now we have no more
+		* servers to ask. We signal this to the rest of resolver by
+		* setting DNSSEC_BOGUS flag. */
+		qry->flags.DNSSEC_BOGUS = true;
+	}
+
+	WITH_VERBOSE(qry)
+	{
+	KR_DNAME_GET_STR(zonecut_str, qry->zone_cut.name);
+	if (*transport) {
+		KR_DNAME_GET_STR(ns_name, (*transport)->ns_name);
+		const enum kr_transport_protocol proto = *transport ? (*transport)->protocol : -1;
+		const char *ns_str = kr_straddr(&(*transport)->address.ip);
+		const char *ip_version;
+		switch (proto)
+		{
+		case KR_TRANSPORT_RESOLVE_A:
+		case KR_TRANSPORT_RESOLVE_AAAA:
+			ip_version = (proto == KR_TRANSPORT_RESOLVE_A) ? "A" : "AAAA";
+			VERBOSE_MSG(qry, "=> id: '%05u' choosing to resolve %s: '%s' zone cut: '%s'\n",
+				    qry->id, ip_version, ns_name, zonecut_str);
+			break;
+		default:
+			VERBOSE_MSG(qry, "=> id: '%05u' choosing: '%s'@'%s'"
+				    " with timeout %u ms zone cut: '%s'\n",
+				    qry->id, ns_name, ns_str ? ns_str : "",
+				    (*transport)->timeout, zonecut_str);
+			break;
+		}
+	} else {
+		const char *nxns_msg = nxnsattack_mitigation
+			? " (stopped due to mitigation for NXNSAttack CVE-2020-12667)" : "";
+		VERBOSE_MSG(qry, "=> id: '%05u' no suitable transport, zone cut: '%s'%s\n",
+			    qry->id, zonecut_str, nxns_msg );
+	}
+	}
+}
+
+void iter_error(struct kr_query *qry, const struct kr_transport *transport,
+		enum kr_selection_error sel_error)
+{
+	if (!qry->server_selection.initialized) {
+		return;
+	}
+	struct iter_local_state *local_state = qry->server_selection.local_state->private;
+	struct address_state *addr_state = get_address_state(local_state, transport);
+	local_state->last_error = sel_error;
+	error(qry, addr_state, transport, sel_error);
+}
+
+void iter_update_rtt(struct kr_query *qry, const struct kr_transport *transport,
+		     unsigned rtt)
+{
+	if (!qry->server_selection.initialized) {
+		return;
+	}
+	struct iter_local_state *local_state = qry->server_selection.local_state->private;
+	struct address_state *addr_state = get_address_state(local_state, transport);
+	update_rtt(qry, addr_state, transport, rtt);
+}
diff --git a/lib/selection_iter.h b/lib/selection_iter.h
new file mode 100644
index 0000000..ed84447
--- /dev/null
+++ b/lib/selection_iter.h
@@ -0,0 +1,14 @@
+/*  Copyright (C) 2014-2020 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#pragma once
+
+#include "lib/selection.h"
+
+void iter_local_state_alloc(struct knot_mm *mm, void **local_state);
+void iter_choose_transport(struct kr_query *qry, struct kr_transport **transport);
+void iter_error(struct kr_query *qry, const struct kr_transport *transport,
+		enum kr_selection_error sel_error);
+void iter_update_rtt(struct kr_query *qry, const struct kr_transport *transport,
+		     unsigned rtt);
diff --git a/lib/test_module.c b/lib/test_module.c
new file mode 100644
index 0000000..592f535
--- /dev/null
+++ b/lib/test_module.c
@@ -0,0 +1,39 @@
+/*  Copyright (C) 201 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#include "tests/unit/test.h"
+#include "lib/module.h"
+
+static void test_module_params(void **state)
+{
+	struct kr_module module;
+	assert_int_equal(kr_module_load(NULL, NULL, NULL), kr_error(EINVAL));
+	assert_int_equal(kr_module_load(&module, NULL, NULL), kr_error(EINVAL));
+	kr_module_unload(NULL);
+}
+
+static void test_module_builtin(void **state)
+{
+	struct kr_module module;
+	assert_int_equal(kr_module_load(&module, "iterate", NULL), 0);
+	kr_module_unload(&module);
+}
+
+static void test_module_c(void **state)
+{
+	struct kr_module module;
+	assert_int_equal(kr_module_load(&module, "mock_cmodule", "tests/unit"), 0);
+	kr_module_unload(&module);
+}
+
+int main(void)
+{
+	const UnitTest tests[] = {
+		unit_test(test_module_params),
+		unit_test(test_module_builtin),
+		unit_test(test_module_c),
+	};
+
+	return run_tests(tests);
+}
diff --git a/lib/test_rplan.c b/lib/test_rplan.c
new file mode 100644
index 0000000..e041973
--- /dev/null
+++ b/lib/test_rplan.c
@@ -0,0 +1,75 @@
+/*  Copyright (C) 2014-2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#include "tests/unit/test.h"
+#include "lib/resolve.h"
+#include "lib/rplan.h"
+
+static void test_rplan_params(void **state)
+{
+	/* NULL rplan */
+
+	assert_int_equal(kr_rplan_init(NULL, NULL, NULL), KNOT_EINVAL);
+	assert_null((void *)kr_rplan_push(NULL, NULL, NULL, 0, 0));
+	assert_int_equal(kr_rplan_pop(NULL, NULL), KNOT_EINVAL);
+	assert_true(kr_rplan_empty(NULL) == true);
+	kr_rplan_deinit(NULL);
+
+	/* NULL mandatory parameters */
+
+	struct kr_rplan rplan;
+	assert_int_equal(kr_rplan_init(&rplan, NULL, NULL), KNOT_EOK);
+	assert_null((void *)kr_rplan_push(&rplan, NULL, NULL, 0, 0));
+	assert_int_equal(kr_rplan_pop(&rplan, NULL), KNOT_EINVAL);
+	assert_true(kr_rplan_empty(&rplan) == true);
+	kr_rplan_deinit(&rplan);
+}
+
+static void test_rplan_push(void **state)
+{
+	knot_mm_t mm;
+	test_mm_ctx_init(&mm);
+	struct kr_request request = {
+		.pool = mm,
+		.options = { 0 },
+	};
+
+	struct kr_rplan rplan;
+	kr_rplan_init(&rplan, &request, &mm);
+
+	/* Push query. */
+	assert_non_null((void *)kr_rplan_push(&rplan, NULL, (knot_dname_t *)"", 0, 0));
+
+	kr_rplan_deinit(&rplan);
+}
+
+/**
+ * Set and clear must not omit any bit, especially around byte boundaries.
+ */
+static void test_rplan_flags(void **state)
+{
+	static struct kr_qflags f1, f2, ones, zeros; /* static => initialized to zeroes */
+	assert_true(memcmp(&f1, &f2, sizeof(f1)) == 0); /* sanity check */
+	memset(&ones, 0xff, sizeof(ones)); /* all ones */
+
+	/* test set */
+	kr_qflags_set(&f1, ones);
+	assert_true(memcmp(&f1, &ones, sizeof(f1)) == 0);  /* 1 == 1 */
+
+	/* test clear */
+	memset(&f2, 0xff, sizeof(f2)); /* all ones */
+	kr_qflags_clear(&f2, ones);
+	assert_true(memcmp(&f2, &zeros, sizeof(f1)) == 0);  /* 0 == 0 */
+}
+
+int main(void)
+{
+	const UnitTest tests[] = {
+	        unit_test(test_rplan_params),
+	        unit_test(test_rplan_push),
+	        unit_test(test_rplan_flags)
+	};
+
+	return run_tests(tests);
+}
diff --git a/lib/test_utils.c b/lib/test_utils.c
new file mode 100644
index 0000000..14843a8
--- /dev/null
+++ b/lib/test_utils.c
@@ -0,0 +1,111 @@
+/*  Copyright (C) 2015-2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#include <sys/socket.h>
+#include <stdio.h>
+#include <contrib/cleanup.h>
+
+#include "tests/unit/test.h"
+#include "lib/utils.h"
+
+static void test_strcatdup(void **state)
+{
+	auto_free char *empty_res = kr_strcatdup(0);
+	assert_null(empty_res);
+
+	auto_free char *null_res = kr_strcatdup(1, NULL);
+	assert_null(null_res);
+
+	auto_free char *nullcat_res = kr_strcatdup(2, NULL, "beef");
+	assert_string_equal(nullcat_res, "beef");
+
+	auto_free char *multi_res = kr_strcatdup(3, "need", "beef", "dead");
+	assert_string_equal(multi_res, "needbeefdead");
+
+	/* Test fails if this leaks. */
+	auto_fclose FILE* null_file = fopen("/dev/null", "r");
+	(void)(null_file);
+
+	/* Test fails if this leaks. */
+	auto_close int null_sock = socket(AF_INET, SOCK_DGRAM, 0);
+	(void)(null_sock);
+}
+
+static inline int test_bitcmp(const char *subnet, const char *str_addr, size_t len)
+{
+	char addr_buf[16] = {'\0'};
+	kr_straddr_subnet(addr_buf, str_addr);
+	return kr_bitcmp(subnet, addr_buf, len);
+}
+
+static void test_straddr(void **state)
+{
+	const char *ip4_ok = "1.2.3.0/30";
+	const char *ip4_bad = "1.2.3.0/33";
+	const char *ip4_in = "1.2.3.1";
+	const char *ip4_out = "1.2.3.5";
+	const char *ip6_ok = "7caa::/4";
+	const char *ip6_bad = "7caa::/129";
+	const char *ip6_in = "7caa::aa7c";
+	const char *ip6_out = "8caa::aa7c";
+	/* Parsing family */
+	assert_int_equal(kr_straddr_family(ip4_ok), AF_INET);
+	assert_int_equal(kr_straddr_family(ip4_in), AF_INET);
+	assert_int_equal(kr_straddr_family(ip6_ok), AF_INET6);
+	assert_int_equal(kr_straddr_family(ip6_in), AF_INET6);
+	/* Parsing subnet */
+	char ip4_sub[4], ip6_sub[16];
+	assert_true(kr_straddr_subnet(ip4_sub, ip4_bad) < 0);
+	assert_int_equal(kr_straddr_subnet(ip4_sub, ip4_ok), 30);
+	assert_true(kr_straddr_subnet(ip6_sub, ip6_bad) < 0);
+	assert_int_equal(kr_straddr_subnet(ip6_sub, ip6_ok), 4);
+	/* Matching subnet */
+	assert_int_equal(test_bitcmp(ip4_sub, ip4_in, 30), 0);
+	assert_int_not_equal(test_bitcmp(ip4_sub, ip4_out, 30), 0);
+	assert_int_equal(test_bitcmp(ip6_sub, ip6_in, 4), 0);
+	assert_int_not_equal(test_bitcmp(ip6_sub, ip6_out, 4), 0);
+}
+
+static void test_strptime_diff(void **state)
+{
+	char *format = "%Y-%m-%dT%H:%M:%S";
+	const char *errmsg = NULL;
+	double output;
+
+	errmsg = kr_strptime_diff(format,
+		"2019-01-09T12:06:04",
+		"2019-01-09T12:06:04", &output);
+	assert_true(errmsg == NULL);
+	/* double type -> equality is not reliable */
+	assert_true(output > -0.01 && output < 0.01);
+
+	errmsg = kr_strptime_diff(format,
+		"2019-01-09T12:06:04",
+		"2019-01-09T11:06:04", &output);
+	assert_true(errmsg == NULL);
+	/* double type -> equality is not reliable */
+	assert_true(output > -3600.01 && output < 3600.01);
+
+	/* invalid inputs */
+	errmsg = kr_strptime_diff(format,
+		"2019-01-09T25:06:04",
+		"2019-01-09T11:06:04", &output);
+	assert_true(errmsg != NULL);
+
+	errmsg = kr_strptime_diff("fail",
+		"2019-01-09T23:06:04",
+		"2019-01-09T11:06:04", &output);
+	assert_true(errmsg != NULL);
+}
+
+int main(void)
+{
+	const UnitTest tests[] = {
+		unit_test(test_strcatdup),
+		unit_test(test_straddr),
+		unit_test(test_strptime_diff),
+	};
+
+	return run_tests(tests);
+}
diff --git a/lib/test_zonecut.c b/lib/test_zonecut.c
new file mode 100644
index 0000000..0c85b0c
--- /dev/null
+++ b/lib/test_zonecut.c
@@ -0,0 +1,58 @@
+/*  Copyright (C) 2014-2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#include <netinet/in.h>
+
+#include "tests/unit/test.h"
+#include "lib/zonecut.h"
+
+static void test_zonecut_params(void **state)
+{
+	/* NULL args */
+	struct kr_zonecut cut;
+	assert_int_not_equal(kr_zonecut_init(NULL, NULL, NULL), 0);
+	assert_int_not_equal(kr_zonecut_init(&cut, NULL, NULL), 0);
+	kr_zonecut_deinit(NULL);
+	kr_zonecut_set(NULL, NULL);
+	kr_zonecut_set(&cut, NULL);
+	/* TODO triggerring inner assert:
+	assert_int_not_equal(kr_zonecut_add(NULL, NULL, NULL, 0), 0);
+	*/
+	assert_null((void *)kr_zonecut_find(NULL, NULL));
+	assert_null((void *)kr_zonecut_find(&cut, NULL));
+	assert_int_not_equal(kr_zonecut_set_sbelt(NULL, NULL), 0);
+	assert_int_not_equal(kr_zonecut_find_cached(NULL, NULL, NULL, 0, 0), 0);
+}
+
+static void test_zonecut_copy(void **state)
+{
+	const knot_dname_t *n_root = (const uint8_t *)"";
+	struct kr_zonecut cut1, cut2;
+	kr_zonecut_init(&cut1, n_root, NULL);
+	kr_zonecut_init(&cut2, n_root, NULL);
+	/* Insert some values */
+	const knot_dname_t
+		*n_1 = (const uint8_t *)"\4dead",
+		*n_2 = (const uint8_t *)"\3bee\1f";
+	assert_int_equal(kr_zonecut_add(&cut1, n_1, NULL, 0), 0);
+	assert_int_equal(kr_zonecut_add(&cut1, n_2, NULL, 0), 0);
+	/* Copy */
+	assert_int_equal(kr_zonecut_copy(&cut2, &cut1), 0);
+	/* Check if exist */
+	assert_non_null(kr_zonecut_find(&cut2, n_1));
+	assert_non_null(kr_zonecut_find(&cut2, n_2));
+	assert_null(kr_zonecut_find(&cut2, (const uint8_t *)"\5death"));
+	kr_zonecut_deinit(&cut1);
+	kr_zonecut_deinit(&cut2);
+}
+
+int main(void)
+{
+	const UnitTest tests[] = {
+	        unit_test(test_zonecut_params),
+	        unit_test(test_zonecut_copy)
+	};
+
+	return run_tests(tests);
+}
diff --git a/lib/utils.c b/lib/utils.c
new file mode 100644
index 0000000..4aad305
--- /dev/null
+++ b/lib/utils.c
@@ -0,0 +1,1256 @@
+/*  Copyright (C) 2014-2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#include "lib/utils.h"
+
+#include "contrib/ccan/asprintf/asprintf.h"
+#include "contrib/cleanup.h"
+#include "contrib/ucw/mempool.h"
+#include "kresconfig.h"
+#include "lib/defines.h"
+#include "lib/generic/array.h"
+#include "lib/module.h"
+#include "lib/selection.h"
+#include "lib/resolve.h"
+
+#include <gnutls/gnutls.h>
+#include <libknot/descriptor.h>
+#include <libknot/dname.h>
+#include <libknot/rrset-dump.h>
+#include <libknot/rrtype/rrsig.h>
+#include <libknot/version.h>
+#include <uv.h>
+
+#include <arpa/inet.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/time.h>
+#include <sys/stat.h>
+#include <sys/statvfs.h>
+#include <sys/un.h>
+
+/* Always compile-in log symbols, even if disabled. */
+#undef kr_verbose_status
+#undef kr_verbose_set
+
+/* Logging & debugging */
+bool kr_verbose_status = false;
+
+/*
+ * Macros.
+ */
+#define strlen_safe(x) ((x) ? strlen(x) : 0)
+
+/**
+ * @internal Convert 16bit unsigned to string, keeps leading spaces.
+ * @note Always fills dst length = 5
+ * Credit: http://computer-programming-forum.com/46-asm/7aa4b50bce8dd985.htm
+ */
+static inline int u16tostr(uint8_t *dst, uint16_t num)
+{
+	uint32_t tmp = num * (((1 << 28) / 10000) + 1) - (num / 4);
+	for(size_t i = 0; i < 5; i++) {
+		dst[i] = '0' + (char) (tmp >> 28);
+		tmp = (tmp & 0x0fffffff) * 10;
+	}
+	return 5;
+}
+
+/*
+ * Cleanup callbacks.
+ */
+
+static void kres_gnutls_log(int level, const char *message)
+{
+	kr_log_verbose("[gnutls] (%d) %s", level, message);
+}
+
+bool kr_verbose_set(bool status)
+{
+#ifndef NOVERBOSELOG
+	kr_verbose_status = status;
+
+	/* gnutls logs messages related to our TLS and also libdnssec,
+	 * and the logging is set up in a global way only */
+	if (status) {
+		gnutls_global_set_log_function(kres_gnutls_log);
+	}
+	gnutls_global_set_log_level(status ? 5 : 0);
+#endif
+	return kr_verbose_status;
+}
+
+static void kr_vlog_req(
+	const struct kr_request * const req, uint32_t qry_uid,
+	const unsigned int indent, const char *source, const char *fmt,
+	va_list args)
+{
+	struct mempool *mp = mp_new(512);
+
+	const uint32_t req_uid = req ? req->uid : 0;
+	char *msg = mp_printf(mp, "[%05u.%02u][%-4s] %*s",
+				req_uid, qry_uid, source, indent, "");
+
+	msg = mp_vprintf_append(mp, msg, fmt, args);
+
+	if (kr_log_rtrace_enabled(req))
+		req->trace_log(req, msg);
+	else
+		/* caller is responsible for detecting verbose mode, use QRVERBOSE() macro */
+		printf("%s", msg);
+
+	mp_delete(mp);
+}
+
+void kr_log_req(const struct kr_request * const req, uint32_t qry_uid,
+		const unsigned int indent, const char *source, const char *fmt, ...)
+{
+	va_list args;
+	va_start(args, fmt);
+	kr_vlog_req(req, qry_uid, indent, source, fmt, args);
+	va_end(args);
+}
+
+void kr_log_q(const struct kr_query * const qry,
+		const char *source, const char *fmt, ...)
+{
+	unsigned ind = 0;
+	for (const struct kr_query *q = qry; q; q = q->parent)
+		ind += 2;
+	const uint32_t qry_uid = qry ? qry->uid : 0;
+	const struct kr_request *req = qry ? qry->request : NULL;
+
+	va_list args;
+	va_start(args, fmt);
+	kr_vlog_req(req, qry_uid, ind, source, fmt, args);
+	va_end(args);
+}
+
+char* kr_strcatdup(unsigned n, ...)
+{
+	if (n < 1) {
+		return NULL;
+	}
+
+	/* Calculate total length */
+	size_t total_len = 0;
+	va_list vl;
+	va_start(vl, n);
+	for (unsigned i = 0; i < n; ++i) {
+		char *item = va_arg(vl, char *);
+		const size_t new_len = total_len + strlen_safe(item);
+		if (unlikely(new_len < total_len)) {
+			va_end(vl);
+			return NULL;
+		}
+		total_len = new_len;
+	}
+	va_end(vl);
+
+	/* Allocate result and fill */
+	char *result = NULL;
+	if (total_len > 0) {
+		if (unlikely(total_len + 1 == 0)) return NULL;
+		result = malloc(total_len + 1);
+	}
+	if (result) {
+		char *stream = result;
+		va_start(vl, n);
+		for (unsigned i = 0; i < n; ++i) {
+			char *item = va_arg(vl, char *);
+			if (item) {
+				size_t len = strlen(item);
+				memcpy(stream, item, len + 1);
+				stream += len;
+			}
+		}
+		va_end(vl);
+	}
+
+	return result;
+}
+
+char * kr_absolutize_path(const char *dirname, const char *fname)
+{
+	assert(dirname && fname);
+	char *result;
+	int aret;
+	if (dirname[0] == '/') { // absolute path is easier
+		aret = asprintf(&result, "%s/%s", dirname, fname);
+	} else { // relative path, but don't resolve symlinks
+		char buf[PATH_MAX];
+		const char *cwd = getcwd(buf, sizeof(buf));
+		if (!cwd)
+			return NULL; // errno has been set already
+		if (strcmp(dirname, ".") == 0) {
+			// get rid of one common case of extraneous "./"
+			aret = asprintf(&result, "%s/%s", cwd, fname);
+		} else {
+			aret = asprintf(&result, "%s/%s/%s", cwd, dirname, fname);
+		}
+	}
+	if (aret > 0)
+		return result;
+	errno = -aret;
+	return NULL;
+}
+
+int kr_memreserve(void *baton, void **mem, size_t elm_size, size_t want, size_t *have)
+{
+    if (*have >= want) {
+        return 0;
+    } else {
+        knot_mm_t *pool = baton;
+        size_t next_size = array_next_count(want);
+        void *mem_new = mm_alloc(pool, next_size * elm_size);
+        if (mem_new != NULL) {
+	    if (*mem) { /* 0-length memcpy from NULL isn't technically OK */
+		memcpy(mem_new, *mem, (*have)*(elm_size));
+		mm_free(pool, *mem);
+	    }
+            *mem = mem_new;
+            *have = next_size;
+            return 0;
+        }
+    }
+    return -1;
+}
+
+static int pkt_recycle(knot_pkt_t *pkt, bool keep_question)
+{
+	/* The maximum size of a header + query name + (class, type) */
+	uint8_t buf[KNOT_WIRE_HEADER_SIZE + KNOT_DNAME_MAXLEN + 2 * sizeof(uint16_t)];
+
+	/* Save header and the question section */
+	size_t base_size = KNOT_WIRE_HEADER_SIZE;
+	if (keep_question) {
+		base_size += knot_pkt_question_size(pkt);
+	}
+	assert(base_size <= sizeof(buf));
+	memcpy(buf, pkt->wire, base_size);
+
+	/* Clear the packet and its auxiliary structures */
+	knot_pkt_clear(pkt);
+
+	/* Restore header and question section and clear counters */
+	pkt->size = base_size;
+	memcpy(pkt->wire, buf, base_size);
+	knot_wire_set_qdcount(pkt->wire, keep_question);
+	knot_wire_set_ancount(pkt->wire, 0);
+	knot_wire_set_nscount(pkt->wire, 0);
+	knot_wire_set_arcount(pkt->wire, 0);
+
+	/* Reparse question */
+	knot_pkt_begin(pkt, KNOT_ANSWER);
+	return knot_pkt_parse_question(pkt);
+}
+
+int kr_pkt_recycle(knot_pkt_t *pkt)
+{
+	return pkt_recycle(pkt, false);
+}
+
+int kr_pkt_clear_payload(knot_pkt_t *pkt)
+{
+	return pkt_recycle(pkt, knot_wire_get_qdcount(pkt->wire));
+}
+
+int kr_pkt_put(knot_pkt_t *pkt, const knot_dname_t *name, uint32_t ttl,
+               uint16_t rclass, uint16_t rtype, const uint8_t *rdata, uint16_t rdlen)
+{
+	/* LATER(opt.): there's relatively lots of copying, but ATM kr_pkt_put()
+	 * isn't considered to be used in any performance-critical parts (just lua). */
+	if (!pkt || !name)  {
+		return kr_error(EINVAL);
+	}
+	/* Create empty RR */
+	knot_rrset_t rr;
+	knot_rrset_init(&rr, knot_dname_copy(name, &pkt->mm), rtype, rclass, ttl);
+	/* Create RDATA */
+	knot_rdata_t *rdata_tmp = mm_alloc(&pkt->mm, offsetof(knot_rdata_t, data) + rdlen);
+	knot_rdata_init(rdata_tmp, rdlen, rdata);
+	knot_rdataset_add(&rr.rrs, rdata_tmp, &pkt->mm);
+	mm_free(&pkt->mm, rdata_tmp); /* we're always on mempool for now, but whatever */
+	/* Append RR */
+	return knot_pkt_put(pkt, 0, &rr, KNOT_PF_FREE);
+}
+
+void kr_pkt_make_auth_header(knot_pkt_t *pkt)
+{
+	assert(pkt && pkt->wire);
+	knot_wire_clear_ad(pkt->wire);
+	knot_wire_set_aa(pkt->wire);
+}
+
+const char *kr_inaddr(const struct sockaddr *addr)
+{
+	if (!addr) {
+		return NULL;
+	}
+	switch (addr->sa_family) {
+	case AF_INET:  return (const char *)&(((const struct sockaddr_in *)addr)->sin_addr);
+	case AF_INET6: return (const char *)&(((const struct sockaddr_in6 *)addr)->sin6_addr);
+	default:       return NULL;
+	}
+}
+
+int kr_inaddr_family(const struct sockaddr *addr)
+{
+	if (!addr)
+		return AF_UNSPEC;
+	return addr->sa_family;
+}
+
+int kr_inaddr_len(const struct sockaddr *addr)
+{
+	if (!addr) {
+		return kr_error(EINVAL);
+	}
+	return kr_family_len(addr->sa_family);
+}
+
+int kr_sockaddr_len(const struct sockaddr *addr)
+{
+	if (!addr) {
+		return kr_error(EINVAL);
+	}
+	switch (addr->sa_family) {
+	case AF_INET:  return sizeof(struct sockaddr_in);
+	case AF_INET6: return sizeof(struct sockaddr_in6);
+	case AF_UNIX:  return sizeof(struct sockaddr_un);
+	default:       return kr_error(EINVAL);
+	}
+}
+
+int kr_sockaddr_cmp(const struct sockaddr *left, const struct sockaddr *right)
+{
+	if (!left || !right) {
+		return kr_error(EINVAL);
+	}
+	if (left->sa_family != right->sa_family) {
+		return kr_error(EFAULT);
+	}
+	if (left->sa_family == AF_INET) {
+		struct sockaddr_in *left_in = (struct sockaddr_in *)left;
+		struct sockaddr_in *right_in = (struct sockaddr_in *)right;
+		if (left_in->sin_addr.s_addr != right_in->sin_addr.s_addr) {
+			return kr_error(EFAULT);
+		}
+		if (left_in->sin_port != right_in->sin_port) {
+			return kr_error(EFAULT);
+		}
+	} else if (left->sa_family == AF_INET6) {
+		struct sockaddr_in6 *left_in6 = (struct sockaddr_in6 *)left;
+		struct sockaddr_in6 *right_in6 = (struct sockaddr_in6 *)right;
+		if (memcmp(&left_in6->sin6_addr, &right_in6->sin6_addr,
+			   sizeof(struct in6_addr)) != 0) {
+			return kr_error(EFAULT);
+		}
+		if (left_in6->sin6_port != right_in6->sin6_port) {
+			return kr_error(EFAULT);
+		}
+	} else {
+		return kr_error(ENOENT);
+	}
+	return kr_ok();
+}
+
+uint16_t kr_inaddr_port(const struct sockaddr *addr)
+{
+	if (!addr) {
+		return 0;
+	}
+	switch (addr->sa_family) {
+	case AF_INET:  return ntohs(((const struct sockaddr_in *)addr)->sin_port);
+	case AF_INET6: return ntohs(((const struct sockaddr_in6 *)addr)->sin6_port);
+	default:       return 0;
+	}
+}
+
+void kr_inaddr_set_port(struct sockaddr *addr, uint16_t port)
+{
+	if (!addr) {
+		return;
+	}
+	switch (addr->sa_family) {
+	case AF_INET:  ((struct sockaddr_in *)addr)->sin_port = htons(port);
+	case AF_INET6: ((struct sockaddr_in6 *)addr)->sin6_port = htons(port);
+	default: break;
+	}
+}
+
+int kr_inaddr_str(const struct sockaddr *addr, char *buf, size_t *buflen)
+{
+	if (!addr) {
+		return kr_error(EINVAL);
+	}
+	return kr_ntop_str(addr->sa_family, kr_inaddr(addr), kr_inaddr_port(addr),
+			   buf, buflen);
+}
+
+int kr_ntop_str(int family, const void *src, uint16_t port, char *buf, size_t *buflen)
+{
+	if (!src || !buf || !buflen) {
+		return kr_error(EINVAL);
+	}
+
+	if (!inet_ntop(family, src, buf, *buflen)) {
+		return kr_error(errno);
+	}
+	const int len = strlen(buf);
+	const int len_need = len + 1 + 5 + 1;
+	if (len_need > *buflen) {
+		*buflen = len_need;
+		return kr_error(ENOSPC);
+	}
+	*buflen = len_need;
+	buf[len] = '#';
+	u16tostr((uint8_t *)&buf[len + 1], port);
+	buf[len_need - 1] = 0;
+	return kr_ok();
+}
+
+int kr_straddr_family(const char *addr)
+{
+	if (!addr) {
+		return kr_error(EINVAL);
+	}
+	if (addr[0] == '/') {
+		return AF_UNIX;
+	}
+	if (strchr(addr, ':')) {
+		return AF_INET6;
+	}
+	return AF_INET;
+}
+
+int kr_family_len(int family)
+{
+	switch (family) {
+	case AF_INET:  return sizeof(struct in_addr);
+	case AF_INET6: return sizeof(struct in6_addr);
+	default:       return kr_error(EINVAL);
+	}
+}
+
+struct sockaddr * kr_straddr_socket(const char *addr, int port, knot_mm_t *pool)
+{
+	switch (kr_straddr_family(addr)) {
+	case AF_INET: {
+		struct sockaddr_in *res = mm_alloc(pool, sizeof(*res));
+		if (uv_ip4_addr(addr, port, res) >= 0) {
+			return (struct sockaddr *)res;
+		} else {
+			mm_free(pool, res);
+			return NULL;
+		}
+	}
+	case AF_INET6: {
+		struct sockaddr_in6 *res = mm_alloc(pool, sizeof(*res));
+		if (uv_ip6_addr(addr, port, res) >= 0) {
+			return (struct sockaddr *)res;
+		} else {
+			mm_free(pool, res);
+			return NULL;
+		}
+	}
+	case AF_UNIX: {
+		struct sockaddr_un *res;
+		const size_t alen = strlen(addr) + 1;
+		if (alen > sizeof(res->sun_path)) {
+			return NULL;
+		}
+		res = mm_alloc(pool, sizeof(*res));
+		res->sun_family = AF_UNIX;
+		memcpy(res->sun_path, addr, alen);
+		return (struct sockaddr *)res;
+	}
+	default:
+		assert(!EINVAL);
+		return NULL;
+	}
+}
+
+int kr_straddr_subnet(void *dst, const char *addr)
+{
+	if (!dst || !addr) {
+		return kr_error(EINVAL);
+	}
+	/* Parse subnet */
+	int bit_len = 0;
+	int family = kr_straddr_family(addr);
+	auto_free char *addr_str = strdup(addr);
+	char *subnet = strchr(addr_str, '/');
+	if (subnet) {
+		*subnet = '\0';
+		subnet += 1;
+		bit_len = strtol(subnet, NULL, 10);
+		/* Check client subnet length */
+		const int max_len = (family == AF_INET6) ? 128 : 32;
+		if (bit_len < 0 || bit_len > max_len) {
+			return kr_error(ERANGE);
+		}
+	} else {
+		/* No subnet, use maximal subnet length. */
+		bit_len = (family == AF_INET6) ? 128 : 32;
+	}
+	/* Parse address */
+	int ret = inet_pton(family, addr_str, dst);
+	if (ret != 1) {
+		return kr_error(EILSEQ);
+	}
+
+	return bit_len;
+}
+
+int kr_straddr_split(const char *instr, char ipaddr[static restrict (INET6_ADDRSTRLEN + 1)],
+		     uint16_t *port)
+{
+	assert(instr && ipaddr && port);
+	/* Find where port number starts. */
+	const char *p_start = strchr(instr, '@');
+	if (!p_start)
+		p_start = strchr(instr, '#');
+	if (p_start) { /* Get and check the port number. */
+		if (p_start[1] == '\0') /* Don't accept empty port string. */
+			return kr_error(EILSEQ);
+		char *p_end;
+		long p = strtol(p_start + 1, &p_end, 10);
+		if (*p_end != '\0' || p <= 0 || p > UINT16_MAX)
+			return kr_error(EILSEQ);
+		*port = p;
+	}
+	/* Copy the address. */
+	const size_t addrlen = p_start ? p_start - instr : strlen(instr);
+	if (addrlen > INET6_ADDRSTRLEN)
+		return kr_error(EILSEQ);
+	memcpy(ipaddr, instr, addrlen);
+	ipaddr[addrlen] = '\0';
+	return kr_ok();
+}
+
+int kr_straddr_join(const char *addr, uint16_t port, char *buf, size_t *buflen)
+{
+	if (!addr || !buf || !buflen) {
+		return kr_error(EINVAL);
+	}
+
+	struct sockaddr_storage ss;
+	int family = kr_straddr_family(addr);
+	if (family == kr_error(EINVAL) || inet_pton(family, addr, &ss) != 1) {
+		return kr_error(EINVAL);
+	}
+
+	int len = strlen(addr);
+	if (len + 6 >= *buflen) {
+		return kr_error(ENOSPC);
+	}
+
+	memcpy(buf, addr, len + 1);
+	buf[len] = '#';
+	u16tostr((uint8_t *)&buf[len + 1], port);
+	len += 6;
+	buf[len] = 0;
+	*buflen = len;
+
+	return kr_ok();
+}
+
+int kr_bitcmp(const char *a, const char *b, int bits)
+{
+	/* We're using the function from lua directly, so at least for now
+	 * we avoid crashing on bogus inputs.  Meaning: NULL is ordered before
+	 * anything else, and negative length is the same as zero.
+	 * TODO: review the call sites and probably remove the checks. */
+	if (bits <= 0 || (!a && !b)) {
+		return 0;
+	} else if (!a) {
+		return -1;
+	} else if (!b) {
+		return 1;
+	}
+
+	assert((a && b && bits >= 0)  ||  bits == 0);
+	/* Compare part byte-divisible part. */
+	const size_t chunk = bits / 8;
+	int ret = memcmp(a, b, chunk);
+	if (ret != 0) {
+		return ret;
+	}
+	a += chunk;
+	b += chunk;
+	bits -= chunk * 8;
+	/* Compare last partial byte address block. */
+	if (bits > 0) {
+		const size_t shift = (8 - bits);
+		ret = ((uint8_t)(*a >> shift) - (uint8_t)(*b >> shift));
+	}
+	return ret;
+}
+
+int kr_rrkey(char *key, uint16_t class, const knot_dname_t *owner,
+	     uint16_t type, uint16_t additional)
+{
+	if (!key || !owner) {
+		return kr_error(EINVAL);
+	}
+	uint8_t *key_buf = (uint8_t *)key;
+	int ret = u16tostr(key_buf, class);
+	if (ret <= 0) {
+		return ret;
+	}
+	key_buf += ret;
+	ret = knot_dname_to_wire(key_buf, owner, KNOT_DNAME_MAXLEN);
+	if (ret <= 0) {
+		return ret;
+	}
+	knot_dname_to_lower(key_buf);
+	key_buf += ret - 1;
+	ret = u16tostr(key_buf, type);
+	if (ret <= 0) {
+		return ret;
+	}
+	key_buf += ret;
+	ret = u16tostr(key_buf, additional);
+	if (ret <= 0) {
+		return ret;
+	}
+	key_buf[ret] = '\0';
+	return (char *)&key_buf[ret] - key;
+}
+
+/** Return whether two RRsets match, i.e. would form the same set; see ranked_rr_array_t */
+static inline bool rrsets_match(const knot_rrset_t *rr1, const knot_rrset_t *rr2)
+{
+	bool match = rr1->type == rr2->type && rr1->rclass == rr2->rclass;
+	if (match && rr2->type == KNOT_RRTYPE_RRSIG) {
+		match = match && knot_rrsig_type_covered(rr1->rrs.rdata)
+				  == knot_rrsig_type_covered(rr2->rrs.rdata);
+	}
+	match = match && knot_dname_is_equal(rr1->owner, rr2->owner);
+	return match;
+}
+
+/** Ensure that an index in a ranked array won't cause "duplicate" RRsets on wire.
+ *
+ * Other entries that would form the same RRset get to_wire = false.
+ * See also rrsets_match.
+ */
+static int to_wire_ensure_unique(ranked_rr_array_t *array, size_t index)
+{
+	bool ok = array && index < array->len;
+	if (!ok) {
+		assert(false);
+		return kr_error(EINVAL);
+	}
+
+	const struct ranked_rr_array_entry *e0 = array->at[index];
+	if (!e0->to_wire) {
+		return kr_ok();
+	}
+
+	for (ssize_t i = array->len - 1; i >= 0; --i) {
+		/* ^ iterate backwards, as the end is more likely in CPU caches */
+		struct ranked_rr_array_entry *ei = array->at[i];
+		if (ei->qry_uid == e0->qry_uid /* assumption: no duplicates within qry */
+		    || !ei->to_wire /* no use for complex comparison if @to_wire */
+		   ) {
+			continue;
+		}
+		if (rrsets_match(ei->rr, e0->rr)) {
+			ei->to_wire = false;
+		}
+	}
+	return kr_ok();
+}
+
+/* Implementation overview of _add() and _finalize():
+ * - for rdata we just maintain a list of pointers (in knot_rrset_t::additional)
+ * - we only construct the final rdataset at the end (and thus more efficiently)
+ */
+typedef array_t(knot_rdata_t *) rdata_array_t;
+int kr_ranked_rrarray_add(ranked_rr_array_t *array, const knot_rrset_t *rr,
+			  uint8_t rank, bool to_wire, uint32_t qry_uid, knot_mm_t *pool)
+{
+	/* rr always has one record per rrset
+	 * check if another rrset with the same
+	 * rclass/type/owner combination exists within current query
+	 * and merge if needed */
+	for (ssize_t i = array->len - 1; i >= 0; --i) {
+		ranked_rr_array_entry_t *stashed = array->at[i];
+		if (stashed->yielded) {
+			break;
+		}
+		if (stashed->qry_uid != qry_uid) {
+			break;
+			/* We do not guarantee merging RRs "across" any point that switched
+			 * to processing a different upstream packet (i.e. qry_uid).
+			 * In particular, iterator never returns KR_STATE_YIELD. */
+		}
+		if (!rrsets_match(stashed->rr, rr)) {
+			continue;
+		}
+		/* Found the entry to merge with.  Check consistency and merge. */
+		bool ok = stashed->rank == rank && !stashed->cached && stashed->in_progress;
+		if (!ok) {
+			assert(false);
+			return kr_error(EEXIST);
+		}
+		/* assert(rr->rrs.count == 1); */
+		/* ^^ shouldn't be a problem for this function, but it's probably a bug */
+
+		/* It may happen that an RRset is first considered useful
+		 * (to_wire = false, e.g. due to being part of glue),
+		 * and later we may find we also want it in the answer. */
+		stashed->to_wire = stashed->to_wire || to_wire;
+
+		/* We just add the reference into this in_progress RRset. */
+		rdata_array_t *ra = stashed->rr->additional;
+		if (ra == NULL) {
+			/* RRset not in array format yet -> convert it. */
+			ra = stashed->rr->additional = mm_alloc(pool, sizeof(*ra));
+			if (!ra) {
+				return kr_error(ENOMEM);
+			}
+			array_init(*ra);
+			int ret = array_reserve_mm(*ra, stashed->rr->rrs.count + rr->rrs.count,
+							kr_memreserve, pool);
+			if (ret) {
+				return kr_error(ret);
+			}
+			knot_rdata_t *r_it = stashed->rr->rrs.rdata;
+			for (int ri = 0; ri < stashed->rr->rrs.count;
+					++ri, r_it = knot_rdataset_next(r_it)) {
+				if (array_push(*ra, r_it) < 0) {
+					abort();
+				}
+			}
+		} else {
+			int ret = array_reserve_mm(*ra, ra->len + rr->rrs.count,
+							kr_memreserve, pool);
+			if (ret) {
+				return kr_error(ret);
+			}
+		}
+		/* Append to the array. */
+		knot_rdata_t *r_it = rr->rrs.rdata;
+		for (int ri = 0; ri < rr->rrs.count;
+				++ri, r_it = knot_rdataset_next(r_it)) {
+			if (array_push(*ra, r_it) < 0) {
+				abort();
+			}
+		}
+		return i;
+	}
+
+	/* No stashed rrset found, add */
+	int ret = array_reserve_mm(*array, array->len + 1, kr_memreserve, pool);
+	if (ret) {
+		return kr_error(ret);
+	}
+
+	ranked_rr_array_entry_t *entry = mm_calloc(pool, 1, sizeof(*entry));
+	if (!entry) {
+		return kr_error(ENOMEM);
+	}
+
+	knot_rrset_t *rr_new = knot_rrset_new(rr->owner, rr->type, rr->rclass, rr->ttl, pool);
+	if (!rr_new) {
+		mm_free(pool, entry);
+		return kr_error(ENOMEM);
+	}
+	rr_new->rrs = rr->rrs;
+	assert(rr_new->additional == NULL);
+
+	entry->qry_uid = qry_uid;
+	entry->rr = rr_new;
+	entry->rank = rank;
+	entry->to_wire = to_wire;
+	entry->in_progress = true;
+	if (array_push(*array, entry) < 0) {
+		/* Silence coverity.  It shouldn't be possible to happen,
+		 * due to the array_reserve_mm call above. */
+		mm_free(pool, entry);
+		return kr_error(ENOMEM);
+	}
+
+	ret = to_wire_ensure_unique(array, array->len - 1);
+	if (ret < 0) return ret;
+	return array->len - 1;
+}
+
+/** Comparator for qsort() on an array of knot_data_t pointers. */
+static int rdata_p_cmp(const void *rp1, const void *rp2)
+{
+	/* Just correct types of the parameters and pass them dereferenced. */
+	const knot_rdata_t
+		*const *r1 = rp1,
+		*const *r2 = rp2;
+	return knot_rdata_cmp(*r1, *r2);
+}
+int kr_ranked_rrarray_finalize(ranked_rr_array_t *array, uint32_t qry_uid, knot_mm_t *pool)
+{
+	for (ssize_t array_i = array->len - 1; array_i >= 0; --array_i) {
+		ranked_rr_array_entry_t *stashed = array->at[array_i];
+		if (stashed->qry_uid != qry_uid) {
+			continue; /* We apparently can't always short-cut the cycle. */
+		}
+		if (!stashed->in_progress) {
+			continue;
+		}
+		rdata_array_t *ra = stashed->rr->additional;
+		if (!ra) {
+			/* No array, so we just need to copy the rdataset. */
+			knot_rdataset_t *rds = &stashed->rr->rrs;
+			knot_rdataset_t tmp = *rds;
+			int ret = knot_rdataset_copy(rds, &tmp, pool);
+			if (ret) {
+				return kr_error(ret);
+			}
+		} else {
+			/* Multiple RRs; first: sort the array. */
+			stashed->rr->additional = NULL;
+			qsort(ra->at, ra->len, sizeof(ra->at[0]), rdata_p_cmp);
+			/* Prune duplicates: NULL all except the last instance. */
+			int dup_count = 0;
+			for (int i = 0; i + 1 < ra->len; ++i) {
+				if (knot_rdata_cmp(ra->at[i], ra->at[i + 1]) == 0) {
+					ra->at[i] = NULL;
+					++dup_count;
+					QRVERBOSE(NULL, "iter", "deleted duplicate RR\n");
+				}
+			}
+			/* Prepare rdataset, except rdata contents. */
+			knot_rdataset_t *rds = &stashed->rr->rrs;
+			rds->size = 0;
+			for (int i = 0; i < ra->len; ++i) {
+				if (ra->at[i]) {
+					rds->size += knot_rdata_size(ra->at[i]->len);
+				}
+			}
+			rds->count = ra->len - dup_count;
+			if (rds->size) {
+				rds->rdata = mm_alloc(pool, rds->size);
+				if (!rds->rdata) {
+					return kr_error(ENOMEM);
+				}
+			} else {
+				rds->rdata = NULL;
+			}
+			/* Everything is ready; now just copy all the rdata. */
+			uint8_t *raw_it = (uint8_t *)rds->rdata;
+			for (int i = 0; i < ra->len; ++i) {
+				if (ra->at[i] && rds->size/*linters*/) {
+					const int size = knot_rdata_size(ra->at[i]->len);
+					memcpy(raw_it, ra->at[i], size);
+					raw_it += size;
+				}
+			}
+			assert(raw_it == (uint8_t *)rds->rdata + rds->size);
+		}
+		stashed->in_progress = false;
+	}
+	return kr_ok();
+}
+
+
+int kr_ranked_rrarray_set_wire(ranked_rr_array_t *array, bool to_wire,
+			       uint32_t qry_uid, bool check_dups,
+			       bool (*extraCheck)(const ranked_rr_array_entry_t *))
+{
+	for (size_t i = 0; i < array->len; ++i) {
+		ranked_rr_array_entry_t *entry = array->at[i];
+		if (entry->qry_uid != qry_uid) {
+			continue;
+		}
+		if (extraCheck != NULL && !extraCheck(entry)) {
+			continue;
+		}
+		entry->to_wire = to_wire;
+		if (check_dups) {
+			int ret = to_wire_ensure_unique(array, i);
+			if (ret) return ret;
+		}
+	}
+	return kr_ok();
+}
+
+
+static char *callprop(struct kr_module *module, const char *prop, const char *input, void *env)
+{
+	if (!module || !module->props || !prop) {
+		return NULL;
+	}
+	for (const struct kr_prop *p = module->props; p && p->name; ++p) {
+		if (p->cb != NULL && strcmp(p->name, prop) == 0) {
+			return p->cb(env, module, input);
+		}
+	}
+	return NULL;
+}
+
+char *kr_module_call(struct kr_context *ctx, const char *module, const char *prop, const char *input)
+{
+	if (!ctx || !ctx->modules || !module || !prop) {
+		return NULL;
+	}
+	module_array_t *mod_list = ctx->modules;
+	for (size_t i = 0; i < mod_list->len; ++i) {
+		struct kr_module *mod = mod_list->at[i];
+		if (strcmp(mod->name, module) == 0) {
+			return callprop(mod, prop, input, ctx);
+		}
+	}
+	return NULL;
+}
+
+static void flags_to_str(char *dst, const knot_pkt_t *pkt, size_t maxlen)
+{
+	int offset = 0;
+	int ret = 0;
+	struct {
+		uint8_t (*get) (const uint8_t *packet);
+		char name[3];
+	} flag[7] = {
+		{knot_wire_get_qr, "qr"},
+		{knot_wire_get_aa, "aa"},
+		{knot_wire_get_rd, "rd"},
+		{knot_wire_get_ra, "ra"},
+		{knot_wire_get_tc, "tc"},
+		{knot_wire_get_ad, "ad"},
+		{knot_wire_get_cd, "cd"}
+	};
+	for (int i = 0; i < 7; ++i) {
+		if (!flag[i].get(pkt->wire)) {
+			continue;
+		}
+		ret = snprintf(dst + offset, maxlen, "%s ", flag[i].name);
+		if (ret <= 0 || ret >= maxlen) {
+			dst[0] = 0;
+			return;
+		}
+		offset += ret;
+		maxlen -= ret;
+	}
+	dst[offset] = 0;
+}
+
+static char *print_section_opt(struct mempool *mp, char *endp, const knot_rrset_t *rr, const uint8_t rcode)
+{
+	uint8_t ercode = knot_edns_get_ext_rcode(rr);
+	uint16_t ext_rcode_id = knot_edns_whole_rcode(ercode, rcode);
+	const char *ext_rcode_str = "Unused";
+	const knot_lookup_t *ext_rcode;
+
+	if (ercode > 0) {
+		ext_rcode = knot_lookup_by_id(knot_rcode_names, ext_rcode_id);
+		if (ext_rcode != NULL) {
+			ext_rcode_str = ext_rcode->name;
+		} else {
+			ext_rcode_str = "Unknown";
+		}
+	}
+
+	return mp_printf_append(mp, endp,
+		";; EDNS PSEUDOSECTION:\n;; "
+		"Version: %u; flags: %s; UDP size: %u B; ext-rcode: %s\n\n",
+		knot_edns_get_version(rr),
+		(knot_edns_do(rr) != 0) ? "do" : "",
+		knot_edns_get_payload(rr),
+		ext_rcode_str);
+
+}
+
+/**
+ * Detect if qname contains an uppercase letter.
+ */
+static bool qname_has_uppercase(const knot_dname_t *qname) {
+	const int len = knot_dname_size(qname) - 1;  /* skip root label at the end */
+	for (int i = 1; i < len; ++i) {  /* skip first length byte */
+		/* Note: this relies on the fact that correct label lengths
+		 * can't pass this test by "luck" and that correctness
+		 * is checked earlier by packet parser. */
+		if (qname[i] >= 'A' && qname[i] <= 'Z')
+			return true;
+	}
+	return false;
+}
+
+char *kr_pkt_text(const knot_pkt_t *pkt)
+{
+	if (!pkt) {
+		return NULL;
+	}
+
+	struct mempool *mp = mp_new(512);
+
+	static const char * snames[] = {
+		";; ANSWER SECTION", ";; AUTHORITY SECTION", ";; ADDITIONAL SECTION"
+	};
+	char flags[32];
+	uint8_t pkt_rcode = knot_wire_get_rcode(pkt->wire);
+	uint8_t pkt_opcode = knot_wire_get_opcode(pkt->wire);
+	const char *rcode_str = "Unknown";
+	const char *opcode_str = "Unknown";
+	const knot_lookup_t *rcode = knot_lookup_by_id(knot_rcode_names, pkt_rcode);
+	const knot_lookup_t *opcode = knot_lookup_by_id(knot_opcode_names, pkt_opcode);
+	uint16_t qry_id = knot_wire_get_id(pkt->wire);
+	uint16_t qdcount = knot_wire_get_qdcount(pkt->wire);
+
+	if (rcode != NULL) {
+		rcode_str = rcode->name;
+	}
+	if (opcode != NULL) {
+		opcode_str = opcode->name;
+	}
+	flags_to_str(flags, pkt, sizeof(flags));
+
+	char *ptr = mp_printf(mp,
+		";; ->>HEADER<<- opcode: %s; status: %s; id: %hu\n"
+		";; Flags: %s QUERY: %hu; ANSWER: %hu; "
+		"AUTHORITY: %hu; ADDITIONAL: %hu\n\n",
+		opcode_str, rcode_str, qry_id,
+		flags,
+		qdcount,
+		knot_wire_get_ancount(pkt->wire),
+		knot_wire_get_nscount(pkt->wire),
+		knot_wire_get_arcount(pkt->wire));
+
+	if (knot_pkt_has_edns(pkt)) {
+		ptr = print_section_opt(mp, ptr, pkt->opt_rr, knot_wire_get_rcode(pkt->wire));
+	}
+
+	if (qdcount == 1) {
+		KR_DNAME_GET_STR(qname, knot_pkt_qname(pkt));
+		KR_RRTYPE_GET_STR(rrtype, knot_pkt_qtype(pkt));
+		const char *qnwarn;
+		if (qname_has_uppercase(knot_pkt_qname(pkt)))
+			qnwarn = \
+"; WARNING! Uppercase letters indicate positions with letter case mismatches!\n"
+";          Normally you should see all-lowercase qname here.\n";
+		else
+			qnwarn = "";
+		ptr = mp_printf_append(mp, ptr, ";; QUESTION SECTION\n%s%s\t\t%s\n", qnwarn, qname, rrtype);
+	} else if (qdcount > 1) {
+		ptr = mp_printf_append(mp, ptr, ";; Warning: unsupported QDCOUNT %hu\n", qdcount);
+	}
+
+	for (knot_section_t i = KNOT_ANSWER; i <= KNOT_ADDITIONAL; ++i) {
+		const knot_pktsection_t *sec = knot_pkt_section(pkt, i);
+		if (sec->count == 0) {
+			continue;
+		}
+
+		ptr = mp_printf_append(mp, ptr, "\n%s\n", snames[i - KNOT_ANSWER]);
+		for (unsigned k = 0; k < sec->count; ++k) {
+			const knot_rrset_t *rr = knot_pkt_rr(sec, k);
+			if (rr->type == KNOT_RRTYPE_OPT) {
+				continue;
+			}
+			auto_free char *rr_text = kr_rrset_text(rr);
+			ptr = mp_printf_append(mp, ptr, "%s", rr_text);
+		}
+	}
+
+	/* Close growing buffer and duplicate result before deleting */
+	char *result = strdup(ptr);
+	mp_delete(mp);
+	return result;
+}
+
+char *kr_rrset_text(const knot_rrset_t *rr)
+{
+	if (!rr) {
+		return NULL;
+	}
+
+	/* Note: knot_rrset_txt_dump will double the size until the rrset fits */
+	size_t bufsize = 128;
+	char *buf = malloc(bufsize);
+	int ret = knot_rrset_txt_dump(rr, &buf, &bufsize, &KNOT_DUMP_STYLE_DEFAULT);
+	if (ret < 0) {
+		free(buf);
+		return NULL;
+	}
+
+	return buf;
+}
+
+uint64_t kr_now()
+{
+	return uv_now(uv_default_loop());
+}
+
+void kr_uv_free_cb(uv_handle_t* handle)
+{
+	free(handle->data);
+}
+
+const char *kr_strptime_diff(const char *format, const char *time1_str,
+		             const char *time0_str, double *diff) {
+	assert(format != NULL);
+	assert(time1_str != NULL);
+	assert(time0_str != NULL);
+	assert(diff != NULL);
+
+	struct tm time1_tm;
+	time_t time1_u;
+	struct tm time0_tm;
+	time_t time0_u;
+
+	char *err = strptime(time1_str, format, &time1_tm);
+	if (err == NULL || err != time1_str + strlen(time1_str))
+		return "strptime failed for time1";
+	time1_tm.tm_isdst = -1; /* determine if DST is active or not */
+	time1_u = mktime(&time1_tm);
+	if (time1_u == (time_t)-1)
+		return "mktime failed for time1";
+
+	err = strptime(time0_str, format, &time0_tm);
+	if (err == NULL || err != time0_str + strlen(time0_str))
+		return "strptime failed for time0";
+	time0_tm.tm_isdst = -1; /* determine if DST is active or not */
+	time0_u = mktime(&time0_tm);
+	if (time0_u == (time_t)-1)
+		return "mktime failed for time0";
+	*diff = difftime(time1_u, time0_u);
+
+	return NULL;
+}
+
+int knot_dname_lf2wire(knot_dname_t * const dst, uint8_t len, const uint8_t *lf)
+{
+	knot_dname_t *d = dst; /* moving "cursor" as we write it out */
+	bool ok = d && (len == 0 || lf);
+	if (!ok) {
+		assert(false);
+		return kr_error(EINVAL);
+	}
+	/* we allow the final zero byte to be omitted */
+	if (!len) {
+		goto finish;
+	}
+	if (lf[len - 1]) {
+		++len;
+	}
+	/* convert the name, one label at a time */
+	int label_end = len - 1; /* index of the zero byte after the current label */
+	while (label_end >= 0) {
+		/* find label_start */
+		int i = label_end - 1;
+		while (i >= 0 && lf[i])
+			--i;
+		const int label_start = i + 1; /* index of the first byte of the current label */
+		const int label_len = label_end - label_start;
+		assert(label_len >= 0);
+		if (label_len > 63 || label_len <= 0)
+			return kr_error(EILSEQ);
+		/* write the label */
+		*d = label_len;
+		++d;
+		memcpy(d, lf + label_start, label_len);
+		d += label_len;
+		/* next label */
+		label_end = label_start - 1;
+	}
+finish:
+	*d = 0; /* the final zero */
+	++d;
+	return d - dst;
+}
+
+static void rnd_noerror(void *data, uint size)
+{
+	int ret = gnutls_rnd(GNUTLS_RND_NONCE, data, size);
+	if (ret) {
+		kr_log_error("gnutls_rnd(): %s\n", gnutls_strerror(ret));
+		abort();
+	}
+}
+void kr_rnd_buffered(void *data, uint size)
+{
+	/* static circular buffer, from index _begin (inclusive) to _end (exclusive) */
+	static uint8_t buf[512/8]; /* gnutls_rnd() works on blocks of 512 bits (chacha) */
+	static uint buf_begin = sizeof(buf);
+
+	if (unlikely(size > sizeof(buf))) {
+		rnd_noerror(data, size);
+		return;
+	}
+	/* Start with contiguous chunk, possibly until the end of buffer. */
+	const uint size1 = MIN(size, sizeof(buf) - buf_begin);
+	uint8_t *d = data;
+	memcpy(d, buf + buf_begin, size1);
+	if (size1 == size) {
+		buf_begin += size1;
+		return;
+	}
+	d += size1;
+	size -= size1;
+	/* Refill the whole buffer, and finish by another contiguous chunk. */
+	rnd_noerror(buf, sizeof(buf));
+	memcpy(d, buf, size);
+	buf_begin = size;
+}
+
+void kr_rrset_init(knot_rrset_t *rrset, knot_dname_t *owner,
+			uint16_t type, uint16_t rclass, uint32_t ttl)
+{
+	assert(rrset);
+	knot_rrset_init(rrset, owner, type, rclass, ttl);
+}
+uint16_t kr_pkt_has_dnssec(const knot_pkt_t *pkt)
+{
+	return knot_pkt_has_dnssec(pkt);
+}
+uint16_t kr_pkt_qclass(const knot_pkt_t *pkt)
+{
+	return knot_pkt_qclass(pkt);
+}
+uint16_t kr_pkt_qtype(const knot_pkt_t *pkt)
+{
+	return knot_pkt_qtype(pkt);
+}
+uint32_t kr_rrsig_sig_inception(const knot_rdata_t *rdata)
+{
+	return knot_rrsig_sig_inception(rdata);
+}
+uint32_t kr_rrsig_sig_expiration(const knot_rdata_t *rdata)
+{
+	return knot_rrsig_sig_expiration(rdata);
+}
+uint16_t kr_rrsig_type_covered(const knot_rdata_t *rdata)
+{
+	return knot_rrsig_type_covered(rdata);
+}
+
+time_t kr_file_mtime (const char* fname) {
+	struct stat fstat;
+
+	if (stat(fname, &fstat) != 0) {
+		return 0;
+	}
+
+	return fstat.st_mtime;
+}
+
+long long kr_fssize(const char *path)
+{
+	if (!path)
+		return kr_error(EINVAL);
+
+	struct statvfs buf;
+	if (statvfs(path, &buf) != 0)
+		return kr_error(errno);
+
+	return buf.f_frsize * buf.f_blocks;
+}
+
+const char * kr_dirent_name(const struct dirent *de)
+{
+	return de ? de->d_name : NULL;
+}
+
diff --git a/lib/utils.h b/lib/utils.h
new file mode 100644
index 0000000..54682bb
--- /dev/null
+++ b/lib/utils.h
@@ -0,0 +1,517 @@
+/*  Copyright (C) 2014-2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#pragma once
+
+#include <assert.h>
+#include <dirent.h>
+#include <stdio.h>
+#include <stdbool.h>
+#include <sys/socket.h>
+#include <sys/time.h>
+#include <netinet/in.h>
+#include <unistd.h>
+
+#include <gnutls/gnutls.h>
+#include <gnutls/crypto.h>
+
+#include <libknot/libknot.h>
+#include <libknot/packet/pkt.h>
+#include <libknot/rrset.h>
+#include <libknot/rrtype/rrsig.h>
+#include <uv.h>
+
+#include "kresconfig.h"
+#include "contrib/mempattern.h"
+#include "lib/defines.h"
+#include "lib/generic/array.h"
+
+struct kr_query;
+struct kr_request;
+
+/*
+ * Logging and debugging.
+ */
+
+/** @brief Callback for request events. */
+typedef void (*trace_callback_f)(struct kr_request *request);
+/**
+ * @brief Callback for request logging handler.
+ * @param[in] msg Log message. Pointer is not valid after handler returns. */
+typedef void (*trace_log_f)(const struct kr_request *request, const char *msg);
+
+#define kr_log_info printf
+#define kr_log_error(...) fprintf(stderr, ## __VA_ARGS__)
+#define kr_log_deprecate(...) fprintf(stderr, "deprecation WARNING: " __VA_ARGS__)
+
+/* Always export these, but override direct calls by macros conditionally. */
+/** Whether in --verbose mode.  Only use this for reading. */
+KR_EXPORT extern bool kr_verbose_status;
+
+/** Set --verbose mode.  Not available if compiled with -DNOVERBOSELOG. */
+KR_EXPORT bool kr_verbose_set(bool status);
+
+/**
+ * @brief Return true if the query has request log handler installed.
+ */
+#define kr_log_rtrace_enabled(req) (__builtin_expect( \
+	(req) && (req)->trace_log, \
+	false))
+
+#define kr_log_qtrace_enabled(qry) (__builtin_expect( \
+	(qry) && kr_log_rtrace_enabled(qry->request), \
+	false))
+
+/**
+ * Log a message through the request log handler or stdout.
+ * Caller is responsible for detecting verbose mode, use QRVERBOSE() macro.
+ * @param  qry_uid query ID to append to request ID, 0 means "no query"
+ * @param  indent level of indentation between [req.qry][source] and message
+ * @param  source message source
+ * @param  fmt message format
+ */
+KR_EXPORT KR_PRINTF(5)
+void kr_log_req(const struct kr_request * const req, uint32_t qry_uid,
+		const unsigned int indent, const char *source, const char *fmt, ...);
+
+/**
+ * Log a message through the request log handler or stdout.
+ * Caller is responsible for detecting verbose mode, use QRVERBOSE() macro.
+ * @param  qry current query
+ * @param  source message source
+ * @param  fmt message format
+ */
+KR_EXPORT KR_PRINTF(3)
+void kr_log_q(const struct kr_query *qry, const char *source, const char *fmt, ...);
+
+#ifdef NOVERBOSELOG
+/* Efficient compile-time disabling of verbose messages. */
+#define kr_verbose_status false
+#define kr_verbose_set(x)
+#endif
+
+/** Block run in --verbose mode; optimized when not run. */
+#define VERBOSE_STATUS __builtin_expect(kr_verbose_status, false)
+#define WITH_VERBOSE(query) if(__builtin_expect(kr_verbose_status || kr_log_qtrace_enabled(query), false))
+#define kr_log_verbose if(VERBOSE_STATUS) printf
+
+#define KR_DNAME_GET_STR(dname_str, dname) \
+	char dname_str[KR_DNAME_STR_MAXLEN]; \
+	knot_dname_to_str(dname_str, (dname), sizeof(dname_str)); \
+	dname_str[sizeof(dname_str) - 1] = 0;
+
+#define KR_RRTYPE_GET_STR(rrtype_str, rrtype) \
+	char rrtype_str[KR_RRTYPE_STR_MAXLEN]; \
+	knot_rrtype_to_string((rrtype), rrtype_str, sizeof(rrtype_str)); \
+	rrtype_str[sizeof(rrtype_str) - 1] = 0;
+
+/* C11 compatibility, but without any implementation so far. */
+#ifndef static_assert
+#define static_assert(cond, msg)
+#endif
+
+// Use this for alocations with mm.
+// Use mm_alloc for alocations into mempool
+
+/** A strcmp() variant directly usable for qsort() on an array of strings. */
+static inline int strcmp_p(const void *p1, const void *p2)
+{
+	return strcmp(*(char * const *)p1, *(char * const *)p2);
+}
+
+
+/** Return time difference in miliseconds.
+  * @note based on the _BSD_SOURCE timersub() macro */
+static inline long time_diff(struct timeval *begin, struct timeval *end) {
+    struct timeval res = {
+        .tv_sec = end->tv_sec - begin->tv_sec,
+        .tv_usec = end->tv_usec - begin->tv_usec
+    };
+    if (res.tv_usec < 0) {
+        --res.tv_sec;
+        res.tv_usec += 1000000;
+    }
+    return res.tv_sec * 1000 + res.tv_usec / 1000;
+}
+
+/** Get current working directory with fallback value. */
+static inline void get_workdir(char *out, size_t len) {
+	if(getcwd(out, len) == NULL) {
+		static const char errprefix[] = "<invalid working directory>";
+		strncpy(out, errprefix, len);
+	}
+}
+
+/** @cond internal Array types */
+struct kr_context;
+
+struct ranked_rr_array_entry {
+	uint32_t qry_uid;
+	uint8_t rank; /**< enum kr_rank */
+	uint8_t revalidation_cnt;
+	bool cached : 1;  /**< Set to true if the entry was written into cache */
+	bool yielded : 1;
+	bool to_wire : 1; /**< whether to be put into the answer */
+	bool expiring : 1; /**< low remaining TTL; see is_expiring; only used in cache ATM */
+	bool in_progress : 1; /**< build of RRset in progress, i.e. different format of RR data */
+	bool dont_cache : 1; /**< avoid caching; useful e.g. for generated data */
+	knot_rrset_t *rr;
+};
+typedef struct ranked_rr_array_entry ranked_rr_array_entry_t;
+
+/** Array of RRsets coming from multiple queries; for struct kr_request.
+ *
+ * Notes:
+ *  - RRSIGs are only considered to form an RRset when the types covered match;
+ *    cache-related code relies on that!
+ *  - RRsets from the same packet (qry_uid) get merged.
+ */
+typedef array_t(ranked_rr_array_entry_t *) ranked_rr_array_t;
+/* @endcond */
+
+/** Concatenate N strings. */
+KR_EXPORT
+char* kr_strcatdup(unsigned n, ...);
+
+/** Construct absolute file path, without resolving symlinks.
+ * \return malloc-ed string or NULL (+errno in that case) */
+KR_EXPORT
+char * kr_absolutize_path(const char *dirname, const char *fname);
+
+/** You probably want kr_rand_* convenience functions instead.
+ * This is a buffered version of gnutls_rnd(GNUTLS_RND_NONCE, ..) */
+KR_EXPORT
+void kr_rnd_buffered(void *data, unsigned int size);
+
+/** Return a few random bytes. */
+static inline uint64_t kr_rand_bytes(unsigned int size)
+{
+	uint64_t result;
+	if (size <= 0 || size > sizeof(result)) {
+		kr_log_error("kr_rand_bytes(): EINVAL\n");
+		abort();
+	}
+	uint8_t data[sizeof(result)];
+	kr_rnd_buffered(data, size);
+	/* I would have liked to dump the random data into a size_t directly,
+	 * but that would work well only on little-endian machines,
+	 * so instead I hope that the compiler will optimize this out.
+	 * (Tested via reading assembly from usual gcc -O2 setup.)
+	 * Alternatively we could waste more rnd bytes, but that seemed worse. */
+	result = 0;
+	for (unsigned int i = 0; i < size; ++ i) {
+		result |= ((size_t)data[i]) << (i * 8);
+	}
+	return result;
+}
+
+/** Throw a pseudo-random coin, succeeding approximately with probability nomin/denomin.
+ * - low precision, only one byte of randomness (or none with extreme parameters)
+ * - tip: use !kr_rand_coin() to get the complementary probability
+ */
+static inline bool kr_rand_coin(unsigned int nomin, unsigned int denomin)
+{
+	/* This function might be called with non-constant values
+	 * so we try to handle odd corner cases instead of crash. */
+	if (nomin >= denomin)
+		return true;
+	else if (nomin <= 0)
+		return false;
+
+	/* threshold = how many parts from 256 are a success */
+	unsigned int threshold = (nomin * 256 + /*rounding*/ denomin / 2) / denomin;
+	if (threshold == 0) threshold = 1;
+	if (threshold == 256) threshold = 255;
+	return (kr_rand_bytes(1) < threshold);
+}
+
+/** Memory reservation routine for knot_mm_t */
+KR_EXPORT
+int kr_memreserve(void *baton, void **mem, size_t elm_size, size_t want, size_t *have);
+
+/** @internal Fast packet reset. */
+KR_EXPORT
+int kr_pkt_recycle(knot_pkt_t *pkt);
+
+/** @internal Clear packet payload. */
+KR_EXPORT
+int kr_pkt_clear_payload(knot_pkt_t *pkt);
+
+/** Construct and put record to packet. */
+KR_EXPORT
+int kr_pkt_put(knot_pkt_t *pkt, const knot_dname_t *name, uint32_t ttl,
+               uint16_t rclass, uint16_t rtype, const uint8_t *rdata, uint16_t rdlen);
+
+/** Set packet header suitable for authoritative answer. (for policy module) */
+KR_EXPORT
+void kr_pkt_make_auth_header(knot_pkt_t *pkt);
+
+/** Simple storage for IPx address or AF_UNSPEC. */
+union inaddr {
+	struct sockaddr ip;
+	struct sockaddr_in ip4;
+	struct sockaddr_in6 ip6;
+};
+
+/** Address bytes for given family. */
+KR_EXPORT KR_PURE
+const char *kr_inaddr(const struct sockaddr *addr);
+/** Address family. */
+KR_EXPORT KR_PURE
+int kr_inaddr_family(const struct sockaddr *addr);
+/** Address length for given family, i.e. sizeof(struct in*_addr). */
+KR_EXPORT KR_PURE
+int kr_inaddr_len(const struct sockaddr *addr);
+/** Sockaddr length for given family, i.e. sizeof(struct sockaddr_in*). */
+KR_EXPORT KR_PURE
+int kr_sockaddr_len(const struct sockaddr *addr);
+/** Compare two given sockaddr.
+ * return 0 - addresses are equal, error code otherwise.
+ */
+KR_EXPORT KR_PURE
+int kr_sockaddr_cmp(const struct sockaddr *left, const struct sockaddr *right);
+/** Port. */
+KR_EXPORT KR_PURE
+uint16_t kr_inaddr_port(const struct sockaddr *addr);
+/** Set port. */
+KR_EXPORT
+void kr_inaddr_set_port(struct sockaddr *addr, uint16_t port);
+
+/** Write string representation for given address as "<addr>#<port>".
+ * \param[in]     addr   the raw address
+ * \param[out]    buf    the buffer for output string
+ * \param[in,out] buflen the available(in) and utilized(out) length, including \0 */
+KR_EXPORT
+int kr_inaddr_str(const struct sockaddr *addr, char *buf, size_t *buflen);
+
+/** Write string representation for given address as "<addr>#<port>".
+ * It's the same as kr_inaddr_str(), but the input address is input in native format
+ * like for inet_ntop() (4 or 16 bytes) and port must be separate parameter.  */
+KR_EXPORT
+int kr_ntop_str(int family, const void *src, uint16_t port, char *buf, size_t *buflen);
+
+/** @internal Create string representation addr#port.
+ *  @return pointer to static string
+ */
+static inline char *kr_straddr(const struct sockaddr *addr)
+{
+	assert(addr != NULL);
+	/* We are the sinle-threaded application */
+	static char str[INET6_ADDRSTRLEN + 1 + 5 + 1];
+	size_t len = sizeof(str);
+	int ret = kr_inaddr_str(addr, str, &len);
+	return ret != kr_ok() || len == 0 ? NULL : str;
+}
+
+
+/** Return address type for string. */
+KR_EXPORT KR_PURE
+int kr_straddr_family(const char *addr);
+/** Return address length in given family (struct in*_addr). */
+KR_EXPORT KR_CONST
+int kr_family_len(int family);
+
+/** Create a sockaddr* from string+port representation.
+ * Also accepts IPv6 link-local and AF_UNIX starting with "/" (ignoring port) */
+KR_EXPORT
+struct sockaddr * kr_straddr_socket(const char *addr, int port, knot_mm_t *pool);
+
+/** Parse address and return subnet length (bits).
+  * @warning 'dst' must be at least `sizeof(struct in6_addr)` long. */
+KR_EXPORT
+int kr_straddr_subnet(void *dst, const char *addr);
+
+/** Splits ip address specified as "addr@port" or "addr#port" into addr and port.
+ * \param[in]  instr zero-terminated input, e.g. "192.0.2.1#12345\0"
+ * \param[out] ipaddr working buffer for the port-less prefix of instr;
+ *                    length >= INET6_ADDRSTRLEN + 1.
+ * \param[out] port written in case it's specified in instr
+ * \return error code
+ * \note Typically you follow this by kr_straddr_socket().
+ * \note Only internet addresses are supported, i.e. no AF_UNIX sockets.
+ */
+KR_EXPORT
+int kr_straddr_split(const char *instr, char ipaddr[static restrict (INET6_ADDRSTRLEN + 1)],
+		     uint16_t *port);
+
+/** Formats ip address and port in "addr#port" format.
+  * and performs validation.
+  * @note Port always formatted as five-character string with leading zeros.
+  * @return kr_error(EINVAL) - addr or buf is NULL or buflen is 0 or
+  *                            addr doesn't contain a valid ip address
+  *         kr_error(ENOSP)  - buflen is too small
+  */
+KR_EXPORT
+int kr_straddr_join(const char *addr, uint16_t port, char *buf, size_t *buflen);
+
+/** Compare memory bitwise.  The semantics is "the same" as for memcmp().
+ *  The partial byte is considered with more-significant bits first,
+ *  so this is e.g. suitable for comparing IP prefixes. */
+KR_EXPORT KR_PURE
+int kr_bitcmp(const char *a, const char *b, int bits);
+
+/** @internal RR map flags. */
+static const uint8_t KEY_FLAG_RRSIG = 0x02;
+static inline uint8_t KEY_FLAG_RANK(const char *key)
+	{ return ((uint8_t)(key[0])) >> 2; }
+static inline bool KEY_COVERING_RRSIG(const char *key)
+	{ return ((uint8_t)(key[0])) & KEY_FLAG_RRSIG; }
+
+/* Stash key = {[5] class, [1-255] owner, [5] type, [5] additional, [1] \x00 } */
+#define KR_RRKEY_LEN (16 + KNOT_DNAME_MAXLEN)
+/** Create unique null-terminated string key for RR.
+  * @param key Destination buffer for key size, MUST be KR_RRKEY_LEN or larger.
+  * @param class RR class.
+  * @param owner RR owner name.
+  * @param type RR type.
+  * @param additional flags (for instance can be used for storing covered type
+  *	   when RR type is RRSIG).
+  * @return key length if successful or an error
+  * */
+KR_EXPORT
+int kr_rrkey(char *key, uint16_t class, const knot_dname_t *owner,
+	     uint16_t type, uint16_t additional);
+
+/** Add RRSet copy to a ranked RR array.
+ *
+ * To convert to standard RRs inside, you need to call _finalize() afterwards,
+ * and the memory of rr->rrs.rdata has to remain until then.
+ *
+ * \return array index (>= 0) or error code (< 0)
+ */
+KR_EXPORT
+int kr_ranked_rrarray_add(ranked_rr_array_t *array, const knot_rrset_t *rr,
+			  uint8_t rank, bool to_wire, uint32_t qry_uid, knot_mm_t *pool);
+/** Finalize in_progress sets - all with matching qry_uid. */
+KR_EXPORT
+int kr_ranked_rrarray_finalize(ranked_rr_array_t *array, uint32_t qry_uid, knot_mm_t *pool);
+
+/** @internal Mark the RRSets from particular query as
+ * "have (not) to be recorded in the final answer".
+ * @param array RRSet array.
+ * @param to_wire Records must be\must not be recorded in final answer.
+ * @param qry_uid Query uid.
+ * @param check_dups When to_wire is true, try to avoid duplicate RRSets.
+ * @param extraCheck optional function checking whether to consider the record
+ * @return 0 or an error
+ */
+int kr_ranked_rrarray_set_wire(ranked_rr_array_t *array, bool to_wire,
+			       uint32_t qry_uid, bool check_dups,
+			       bool (*extraCheck)(const ranked_rr_array_entry_t *));
+
+/**
+ * @return Newly allocated string representation of packet.
+ * Caller has to free() returned string.
+ */
+KR_EXPORT
+char *kr_pkt_text(const knot_pkt_t *pkt);
+
+KR_PURE
+char *kr_rrset_text(const knot_rrset_t *rr);
+
+KR_PURE
+static inline char *kr_dname_text(const knot_dname_t *name) {
+	return knot_dname_to_str_alloc(name);
+}
+
+KR_CONST
+static inline char *kr_rrtype_text(const uint16_t rrtype) {
+	char type_str[32] = {0};
+	knot_rrtype_to_string(rrtype, type_str, sizeof(type_str));
+	return strdup(type_str);
+}
+
+/**
+ * Call module property.
+ */
+KR_EXPORT
+char *kr_module_call(struct kr_context *ctx, const char *module, const char *prop, const char *input);
+
+/** Swap two places.  Note: the parameters need to be without side effects. */
+#define SWAP(x, y) do { /* http://stackoverflow.com/a/3982430/587396 */ \
+	unsigned char swap_temp[sizeof(x) == sizeof(y) ? (ssize_t)sizeof(x) : -1]; \
+	memcpy(swap_temp, &y, sizeof(x)); \
+	memcpy(&y,        &x, sizeof(x)); \
+	memcpy(&x, swap_temp, sizeof(x)); \
+	} while(0)
+
+/** Return the (covered) type of an nonempty RRset. */
+static inline uint16_t kr_rrset_type_maysig(const knot_rrset_t *rr)
+{
+	assert(rr && rr->rrs.count && rr->rrs.rdata);
+	uint16_t type = rr->type;
+	if (type == KNOT_RRTYPE_RRSIG)
+		type = knot_rrsig_type_covered(rr->rrs.rdata);
+	return type;
+}
+
+/** The current time in monotonic milliseconds.
+ *
+ * \note it may be outdated in case of long callbacks; see uv_now().
+ */
+KR_EXPORT
+uint64_t kr_now();
+
+/** Call free(handle->data); it's useful e.g. as a callback in uv_close(). */
+KR_EXPORT void kr_uv_free_cb(uv_handle_t* handle);
+
+/** Convert name from lookup format to wire.  See knot_dname_lf
+ *
+ * \note len bytes are read and len+1 are written with *normal* LF,
+ * 	 but it's also allowed that the final zero byte is omitted in LF.
+ * \return the number of bytes written (>0) or error code (<0)
+ */
+int knot_dname_lf2wire(knot_dname_t *dst, uint8_t len, const uint8_t *lf);
+
+/** Patched knot_dname_lf.  LF for "." has length zero instead of one, for consistency.
+ * (TODO: consistency?)
+ * \param add_wildcard append the wildcard label
+ * \note packet is always NULL
+ */
+static inline int kr_dname_lf(uint8_t *dst, const knot_dname_t *src, bool add_wildcard)
+{
+	knot_dname_storage_t right_aligned_dst;
+	uint8_t *right_aligned_dname_start = knot_dname_lf(src, right_aligned_dst);
+	if (!right_aligned_dname_start) {
+		return kr_error(EINVAL);
+	}
+	int len = right_aligned_dname_start[0];
+	assert(right_aligned_dname_start + 1 + len - KNOT_DNAME_MAXLEN == right_aligned_dst);
+	memcpy(dst + 1, right_aligned_dname_start + 1, len);
+	if (add_wildcard) {
+		if (len + 2 > KNOT_DNAME_MAXLEN)
+			return kr_error(ENOSPC);
+		dst[len + 1] = '*';
+		dst[len + 2] = '\0';
+		len += 2;
+	}
+	dst[0] = len;
+	return KNOT_EOK;
+}
+
+/**
+ * Difference between two calendar times specified as strings.
+ * \param[in]  format format for strptime
+ * \param[out] diff result from C difftime(time1, time0)
+ */
+KR_EXPORT
+const char *kr_strptime_diff(const char *format, const char *time1_str,
+		             const char *time0_str, double *diff);
+
+/* Trivial non-inline wrappers, to be used in lua. */
+KR_EXPORT void kr_rrset_init(knot_rrset_t *rrset, knot_dname_t *owner,
+				uint16_t type, uint16_t rclass, uint32_t ttl);
+KR_EXPORT uint16_t kr_pkt_has_dnssec(const knot_pkt_t *pkt);
+KR_EXPORT uint16_t kr_pkt_qclass(const knot_pkt_t *pkt);
+KR_EXPORT uint16_t kr_pkt_qtype(const knot_pkt_t *pkt);
+KR_EXPORT uint32_t kr_rrsig_sig_inception(const knot_rdata_t *rdata);
+KR_EXPORT uint32_t kr_rrsig_sig_expiration(const knot_rdata_t *rdata);
+KR_EXPORT uint16_t kr_rrsig_type_covered(const knot_rdata_t *rdata);
+
+KR_EXPORT time_t kr_file_mtime (const char* fname);
+/** Return filesystem size in bytes. */
+KR_EXPORT long long kr_fssize(const char *path);
+/** Simply return de->dname. (useful from Lua) */
+KR_EXPORT const char * kr_dirent_name(const struct dirent *de);
+
diff --git a/lib/zonecut.c b/lib/zonecut.c
new file mode 100644
index 0000000..cf7bfea
--- /dev/null
+++ b/lib/zonecut.c
@@ -0,0 +1,570 @@
+/*  Copyright (C) 2014-2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#include "lib/zonecut.h"
+
+#include "contrib/cleanup.h"
+#include "lib/defines.h"
+#include "lib/generic/pack.h"
+#include "lib/layer.h"
+#include "lib/resolve.h"
+#include "lib/rplan.h"
+
+#include <libknot/descriptor.h>
+#include <libknot/packet/wire.h>
+#include <libknot/rrtype/rdname.h>
+
+#define VERBOSE_MSG(qry, ...) QRVERBOSE(qry, "zcut", __VA_ARGS__)
+
+/** Information for one NS name + address type. */
+typedef enum {
+	AI_UNINITED = 0,
+	AI_REPUT,	/**< Don't use this addrset, due to: cache_rep, NO_IPV6, ...
+			 * cache_rep approximates various problems when fetching the RRset. */
+	AI_CYCLED,	/**< Skipped due to cycle detection; see implementation for details. */
+	AI_LAST_BAD = AI_CYCLED, /** bad states: <= AI_LAST_BAD */
+	AI_UNKNOWN,	/**< Don't know status of this RRset; various reasons. */
+	AI_EMPTY,	/**< No usable address (may mean e.g. just NODATA). */
+	AI_OK,		/**< At least one usable address.
+			 * LATER: we might be interested whether it's only glue. */
+} addrset_info_t;
+
+
+static void update_cut_name(struct kr_zonecut *cut, const knot_dname_t *name)
+{
+	if (knot_dname_is_equal(name, cut->name)) {
+		return;
+	}
+	knot_dname_t *next_name = knot_dname_copy(name, cut->pool);
+	mm_free(cut->pool, cut->name);
+	cut->name = next_name;
+}
+
+int kr_zonecut_init(struct kr_zonecut *cut, const knot_dname_t *name, knot_mm_t *pool)
+{
+	if (!cut || !name) {
+		return kr_error(EINVAL);
+	}
+
+	memset(cut, 0, sizeof(*cut));
+	cut->name = knot_dname_copy(name, pool);
+	cut->pool = pool;
+	cut->nsset = trie_create(pool);
+	return cut->name && cut->nsset ? kr_ok() : kr_error(ENOMEM);
+}
+
+/** Completely free a pack_t. */
+static inline void free_addr_set(pack_t *pack, knot_mm_t *pool)
+{
+	if (unlikely(!pack)) {
+		/* promised we don't store NULL packs */
+		assert(false);
+		return;
+	}
+	pack_clear_mm(*pack, mm_free, pool);
+	mm_free(pool, pack);
+}
+/** Trivial wrapper for use in trie_apply, due to ugly casting. */
+static int free_addr_set_cb(trie_val_t *v, void *pool)
+{
+	free_addr_set(*v, pool);
+	return kr_ok();
+}
+
+void kr_zonecut_deinit(struct kr_zonecut *cut)
+{
+	if (!cut) {
+		return;
+	}
+	mm_free(cut->pool, cut->name);
+	if (cut->nsset) {
+		trie_apply(cut->nsset, free_addr_set_cb, cut->pool);
+		trie_free(cut->nsset);
+	}
+	knot_rrset_free(cut->key, cut->pool);
+	knot_rrset_free(cut->trust_anchor, cut->pool);
+}
+
+void kr_zonecut_move(struct kr_zonecut *to, const struct kr_zonecut *from)
+{
+	if (!to || !from) abort();
+	kr_zonecut_deinit(to);
+	memcpy(to, from, sizeof(*to));
+}
+
+void kr_zonecut_set(struct kr_zonecut *cut, const knot_dname_t *name)
+{
+	if (!cut || !name) {
+		return;
+	}
+	knot_rrset_t *key, *ta;
+	key = cut->key; cut->key = NULL;
+	ta = cut->trust_anchor; cut->trust_anchor = NULL;
+	kr_zonecut_deinit(cut);
+	kr_zonecut_init(cut, name, cut->pool);
+	cut->key = key;
+	cut->trust_anchor = ta;
+}
+
+int kr_zonecut_copy(struct kr_zonecut *dst, const struct kr_zonecut *src)
+{
+	if (!dst || !src) {
+		return kr_error(EINVAL);
+	}
+	if (!dst->nsset) {
+		dst->nsset = trie_create(dst->pool);
+	}
+	/* Copy the contents, one by one. */
+	int ret = kr_ok();
+	trie_it_t *it;
+	for (it = trie_it_begin(src->nsset); !trie_it_finished(it); trie_it_next(it)) {
+		size_t klen;
+		const char * const k = trie_it_key(it, &klen);
+		pack_t **new_pack = (pack_t **)trie_get_ins(dst->nsset, k, klen);
+		if (!new_pack) {
+			ret = kr_error(ENOMEM);
+			break;
+		}
+		const pack_t *old_pack = *trie_it_val(it);
+		ret = pack_clone(new_pack, old_pack, dst->pool);
+		if (ret) break;
+	}
+	trie_it_free(it);
+	return ret;
+}
+
+int kr_zonecut_copy_trust(struct kr_zonecut *dst, const struct kr_zonecut *src)
+{
+	knot_rrset_t *key_copy = NULL;
+	knot_rrset_t *ta_copy = NULL;
+
+	if (src->key) {
+		key_copy = knot_rrset_copy(src->key, dst->pool);
+		if (!key_copy) {
+			return kr_error(ENOMEM);
+		}
+	}
+
+	if (src->trust_anchor) {
+		ta_copy = knot_rrset_copy(src->trust_anchor, dst->pool);
+		if (!ta_copy) {
+			knot_rrset_free(key_copy, dst->pool);
+			return kr_error(ENOMEM);
+		}
+	}
+
+	knot_rrset_free(dst->key, dst->pool);
+	dst->key = key_copy;
+	knot_rrset_free(dst->trust_anchor, dst->pool);
+	dst->trust_anchor = ta_copy;
+
+	return kr_ok();
+}
+
+int kr_zonecut_add(struct kr_zonecut *cut, const knot_dname_t *ns, const void *data, int len)
+{
+	if (!cut || !ns || !cut->nsset || (data && len <= 0)) {
+		assert(!EINVAL);
+		return kr_error(EINVAL);
+	}
+	/* Disabled; add_reverse_pair() misuses this for domain name in rdata. */
+	if (false && data && len != sizeof(struct in_addr)
+		  && len != sizeof(struct in6_addr)) {
+		assert(!EINVAL);
+		return kr_error(EINVAL);
+	}
+
+	/* Get a pack_t for the ns. */
+	pack_t **pack = (pack_t **)trie_get_ins(cut->nsset, (const char *)ns, knot_dname_size(ns));
+	if (!pack) return kr_error(ENOMEM);
+	if (*pack == NULL) {
+		*pack = mm_alloc(cut->pool, sizeof(pack_t));
+		if (*pack == NULL) return kr_error(ENOMEM);
+		pack_init(**pack);
+	}
+	/* Insert data (if has any) */
+	if (data == NULL) {
+		return kr_ok();
+	}
+	/* Check for duplicates */
+	if (pack_obj_find(*pack, data, len)) {
+		return kr_ok();
+	}
+	/* Push new address */
+	int ret = pack_reserve_mm(**pack, 1, len, kr_memreserve, cut->pool);
+	if (ret != 0) {
+		return kr_error(ENOMEM);
+	}
+	return pack_obj_push(*pack, data, len);
+}
+
+int kr_zonecut_del(struct kr_zonecut *cut, const knot_dname_t *ns, const void *data, int len)
+{
+	if (!cut || !ns || (data && len <= 0)) {
+		return kr_error(EINVAL);
+	}
+
+	/* Find the address list. */
+	int ret = kr_ok();
+	pack_t *pack = kr_zonecut_find(cut, ns);
+	if (pack == NULL) {
+		return kr_error(ENOENT);
+	}
+	/* Remove address from the pack. */
+	if (data) {
+		ret = pack_obj_del(pack, data, len);
+	}
+	/* No servers left, remove NS from the set. */
+	if (pack->len == 0) {
+		free_addr_set(pack, cut->pool);
+		ret = trie_del(cut->nsset, (const char *)ns, knot_dname_size(ns), NULL);
+		assert(ret == 0); /* only KNOT_ENOENT and that *can't* happen */
+		return (ret == 0) ? kr_ok() : kr_error(ret);
+	}
+
+	return ret;
+}
+
+int kr_zonecut_del_all(struct kr_zonecut *cut, const knot_dname_t *ns)
+{
+	if (!cut || !ns) {
+		return kr_error(EINVAL);
+	}
+
+	/* Find the address list; then free and remove it. */
+	pack_t *pack;
+	int ret = trie_del(cut->nsset, (const char *)ns, knot_dname_size(ns),
+			   (trie_val_t *)&pack);
+	if (ret) { /* deletion failed */
+		assert(ret == KNOT_ENOENT);
+		return kr_error(ENOENT);
+	}
+	free_addr_set(pack, cut->pool);
+	return kr_ok();
+}
+
+pack_t *kr_zonecut_find(struct kr_zonecut *cut, const knot_dname_t *ns)
+{
+	if (!cut || !ns) {
+		return NULL;
+	}
+	trie_val_t *val = trie_get_try(cut->nsset, (const char *)ns, knot_dname_size(ns));
+	/* we get pointer to the pack_t pointer */
+	return val ? (pack_t *)*val : NULL;
+}
+
+static int has_address(trie_val_t *v, void *baton_)
+{
+	const pack_t *pack = *v;
+	const bool found = pack != NULL && pack->len != 0;
+	return found;
+}
+
+bool kr_zonecut_is_empty(struct kr_zonecut *cut)
+{
+	if (!cut || !cut->nsset) {
+		assert(false);
+		return true;
+	}
+	return !trie_apply(cut->nsset, has_address, NULL);
+}
+
+int kr_zonecut_set_sbelt(struct kr_context *ctx, struct kr_zonecut *cut)
+{
+	if (!ctx || !cut || !ctx->root_hints.nsset) {
+		return kr_error(EINVAL);
+	}
+
+	trie_apply(cut->nsset, free_addr_set_cb, cut->pool);
+	trie_clear(cut->nsset);
+
+	const uint8_t *const dname_root = (const uint8_t *)/*sign-cast*/("");
+	update_cut_name(cut, dname_root);
+	/* Copy root hints from resolution context. */
+	return kr_zonecut_copy(cut, &ctx->root_hints);
+}
+
+/** Fetch address for zone cut.  Any rank is accepted (i.e. glue as well). */
+static addrset_info_t fetch_addr(pack_t *addrs, const knot_dname_t *ns, uint16_t rrtype,
+				 knot_mm_t *mm_pool, const struct kr_query *qry)
+// LATER(optim.): excessive data copying
+{
+	int rdlen;
+	switch (rrtype) {
+	case KNOT_RRTYPE_A:
+		rdlen = 4;
+		break;
+	case KNOT_RRTYPE_AAAA:
+		rdlen = 16;
+		break;
+	default:
+		assert(!EINVAL);
+		return AI_UNKNOWN;
+	}
+
+	struct kr_context *ctx = qry->request->ctx;
+	struct kr_cache_p peek;
+	if (kr_cache_peek_exact(&ctx->cache, ns, rrtype, &peek) != 0) {
+		return AI_UNKNOWN;
+	}
+	int32_t new_ttl = kr_cache_ttl(&peek, qry, ns, rrtype);
+	if (new_ttl < 0) {
+		return AI_UNKNOWN;
+	}
+
+	knot_rrset_t cached_rr;
+	knot_rrset_init(&cached_rr, /*const-cast*/(knot_dname_t *)ns, rrtype,
+			KNOT_CLASS_IN, new_ttl);
+	if (kr_cache_materialize(&cached_rr.rrs, &peek, mm_pool) < 0) {
+		return AI_UNKNOWN;
+	}
+
+	/* Reserve memory in *addrs.  Implementation detail:
+	 * pack_t cares for lengths, so we don't store those in the data. */
+	const size_t pack_extra_size = cached_rr.rrs.size
+		- cached_rr.rrs.count * offsetof(knot_rdata_t, len);
+	int ret = pack_reserve_mm(*addrs, cached_rr.rrs.count, pack_extra_size,
+				  kr_memreserve, mm_pool);
+	if (ret) abort(); /* ENOMEM "probably" */
+
+	int usable_cnt = 0;
+	addrset_info_t result = AI_EMPTY;
+	knot_rdata_t *rd = cached_rr.rrs.rdata;
+	for (uint16_t i = 0; i < cached_rr.rrs.count; ++i, rd = knot_rdataset_next(rd)) {
+		if (unlikely(rd->len != rdlen)) {
+			VERBOSE_MSG(qry, "bad NS address length %d for rrtype %d, skipping\n",
+					(int)rd->len, (int)rrtype);
+			continue;
+		}
+		result = AI_OK;
+		++usable_cnt;
+
+		ret = pack_obj_push(addrs, rd->data, rd->len);
+		assert(!ret); /* didn't fit because of incorrectly reserved memory */
+		/* LATER: for now we lose quite some information here,
+		 * as keeping it would need substantial changes on other places,
+		 * and it turned out to be premature optimization (most likely).
+		 * We might e.g. skip adding unusable addresses,
+		 * and either keep some rtt information associated
+		 * or even finish up choosing the set to send packets to.
+		 * Overall there's some overlap with nsrep.c functionality.
+		 */
+	}
+	if (usable_cnt != cached_rr.rrs.count) {
+		VERBOSE_MSG(qry, "usable NS addresses: %d/%d\n",
+				usable_cnt, cached_rr.rrs.count);
+	}
+	return result;
+}
+
+/** Fetch best NS for zone cut. */
+static int fetch_ns(struct kr_context *ctx, struct kr_zonecut *cut,
+		    const knot_dname_t *name, const struct kr_query *qry,
+		    uint8_t * restrict rank)
+{
+	struct kr_cache_p peek;
+	int ret = kr_cache_peek_exact(&ctx->cache, name, KNOT_RRTYPE_NS, &peek);
+	if (ret != 0) {
+		return ret;
+	}
+	/* Note: we accept *any* rank from the cache.  We assume that nothing
+	 * completely untrustworthy could get into the cache, e.g out-of-bailiwick
+	 * records that weren't validated.
+	 */
+	*rank = peek.rank;
+
+	int32_t new_ttl = kr_cache_ttl(&peek, qry, name, KNOT_RRTYPE_NS);
+	if (new_ttl < 0) {
+		return kr_error(ESTALE);
+	}
+	/* Materialize the rdataset temporarily, for simplicity. */
+	knot_rdataset_t ns_rds = { 0 };
+	ret = kr_cache_materialize(&ns_rds, &peek, cut->pool);
+	if (ret < 0) {
+		return ret;
+	}
+
+	/* Insert name servers for this zone cut, addresses will be looked up
+	 * on-demand (either from cache or iteratively) */
+	bool all_bad = true; /**< All NSs (seen so far) are in a bad state. */
+	knot_rdata_t *rdata_i = ns_rds.rdata;
+	for (unsigned i = 0; i < ns_rds.count;
+			++i, rdata_i = knot_rdataset_next(rdata_i)) {
+		const knot_dname_t *ns_name = knot_ns_name(rdata_i);
+		const size_t ns_size = knot_dname_size(ns_name);
+
+		/* Get a new pack within the nsset. */
+		pack_t **pack = (pack_t **)trie_get_ins(cut->nsset,
+					(const char *)ns_name, ns_size);
+		if (!pack) return kr_error(ENOMEM);
+		assert(!*pack); /* not critical, really */
+		*pack = mm_alloc(cut->pool, sizeof(pack_t));
+		if (!*pack) return kr_error(ENOMEM);
+		pack_init(**pack);
+
+		addrset_info_t infos[2];
+
+		/* Fetch NS reputation and decide whether to prefetch A/AAAA records. */
+		infos[0] = fetch_addr(*pack, ns_name, KNOT_RRTYPE_A, cut->pool, qry);
+		infos[1] = fetch_addr(*pack, ns_name, KNOT_RRTYPE_AAAA, cut->pool, qry);
+
+		#if 0 /* rather unlikely to be useful unless changing some zcut code */
+		WITH_VERBOSE(qry) {
+			auto_free char *ns_name_txt = kr_dname_text(ns_name);
+			VERBOSE_MSG(qry, "NS %s infos: %d, %d\n",
+					ns_name_txt, (int)infos[0], (int)infos[1]);
+		}
+		#endif
+
+		/* AI_CYCLED checks.
+		 * If an ancestor query has its zone cut in the state that
+		 * it's looking for name or address(es) of some NS(s),
+		 * we want to avoid doing so with a NS that lies under its cut.
+		 * Instead we need to consider such names unusable in the cut (for now). */
+		if (infos[0] != AI_UNKNOWN && infos[1] != AI_UNKNOWN) {
+			/* Optimization: the following loop would be pointless. */
+			all_bad = false;
+			continue;
+		}
+		for (const struct kr_query *aq = qry; aq->parent; aq = aq->parent) {
+			const struct kr_qflags *aqpf = &aq->parent->flags;
+			if (   (aqpf->AWAIT_CUT  && aq->stype == KNOT_RRTYPE_NS)
+			    || (aqpf->AWAIT_IPV4 && aq->stype == KNOT_RRTYPE_A)
+			    || (aqpf->AWAIT_IPV6 && aq->stype == KNOT_RRTYPE_AAAA)) {
+				if (knot_dname_in_bailiwick(ns_name,
+							aq->parent->zone_cut.name)) {
+					for (int j = 0; j < 2; ++j)
+						if (infos[j] == AI_UNKNOWN)
+							infos[j] = AI_CYCLED;
+					break;
+				}
+			} else {
+				/* This ancestor waits for other reason that
+				 * NS name or address, so we're out of a direct cycle. */
+				break;
+			}
+		}
+		all_bad = all_bad && infos[0] <= AI_LAST_BAD && infos[1] <= AI_LAST_BAD;
+	}
+
+	if (all_bad) { WITH_VERBOSE(qry) {
+		auto_free char *name_txt = kr_dname_text(name);
+		VERBOSE_MSG(qry, "cut %s: all NSs bad, count = %d\n",
+				name_txt, (int)ns_rds.count);
+	} }
+	knot_rdataset_clear(&ns_rds, cut->pool);
+	return all_bad ? ELOOP : kr_ok();
+}
+
+/**
+ * Fetch secure RRSet of given type.
+ */
+static int fetch_secure_rrset(knot_rrset_t **rr, struct kr_cache *cache,
+	const knot_dname_t *owner, uint16_t type, knot_mm_t *pool,
+	const struct kr_query *qry)
+{
+	if (!rr) {
+		assert(!EINVAL);
+		return kr_error(EINVAL);
+	}
+	/* peek, check rank and TTL */
+	struct kr_cache_p peek;
+	int ret = kr_cache_peek_exact(cache, owner, type, &peek);
+	if (ret != 0) {
+		return ret;
+	}
+	if (!kr_rank_test(peek.rank, KR_RANK_SECURE)) {
+		return kr_error(ENOENT);
+	}
+	int32_t new_ttl = kr_cache_ttl(&peek, qry, owner, type);
+	if (new_ttl < 0) {
+		return kr_error(ESTALE);
+	}
+	/* materialize a new RRset */
+	knot_rrset_free(*rr, pool);
+	*rr = mm_alloc(pool, sizeof(knot_rrset_t));
+	if (*rr == NULL) {
+		return kr_error(ENOMEM);
+	}
+	owner = knot_dname_copy(/*const-cast*/(knot_dname_t *)owner, pool);
+	if (!owner) {
+		mm_free(pool, *rr);
+		*rr = NULL;
+		return kr_error(ENOMEM);
+	}
+	knot_rrset_init(*rr, /*const-cast*/(knot_dname_t *)owner, type,
+			KNOT_CLASS_IN, new_ttl);
+	ret = kr_cache_materialize(&(*rr)->rrs, &peek, pool);
+	if (ret < 0) {
+		knot_rrset_free(*rr, pool);
+		*rr = NULL;
+		return ret;
+	}
+
+	return kr_ok();
+}
+
+int kr_zonecut_find_cached(struct kr_context *ctx, struct kr_zonecut *cut,
+			   const knot_dname_t *name, const struct kr_query *qry,
+			   bool * restrict secured)
+{
+	if (!ctx || !cut || !name) {
+		//assert(false);
+		return kr_error(EINVAL);
+	}
+	/* I'm not sure whether the caller always passes a clean state;
+	 * mixing doesn't seem to make sense in any case, so let's clear it.
+	 * We don't bother freeing the packs, as they're on mempool. */
+	trie_clear(cut->nsset);
+	/* Copy name as it may overlap with cut name that is to be replaced. */
+	knot_dname_t *qname = knot_dname_copy(name, cut->pool);
+	if (!qname) {
+		return kr_error(ENOMEM);
+	}
+	/* Start at QNAME. */
+	int ret;
+	const knot_dname_t *label = qname;
+	while (true) {
+		/* Fetch NS first and see if it's insecure. */
+		uint8_t rank = 0;
+		const bool is_root = (label[0] == '\0');
+		ret = fetch_ns(ctx, cut, label, qry, &rank);
+		if (ret == 0) {
+			/* Flag as insecure if cached as this */
+			if (kr_rank_test(rank, KR_RANK_INSECURE)) {
+				*secured = false;
+			}
+			/* Fetch DS and DNSKEY if caller wants secure zone cut */
+			int ret_ds = 1, ret_dnskey = 1;
+			if (*secured || is_root) {
+				ret_ds = fetch_secure_rrset(&cut->trust_anchor, &ctx->cache,
+						label, KNOT_RRTYPE_DS, cut->pool, qry);
+				ret_dnskey = fetch_secure_rrset(&cut->key, &ctx->cache,
+						label, KNOT_RRTYPE_DNSKEY, cut->pool, qry);
+			}
+			update_cut_name(cut, label);
+			WITH_VERBOSE(qry) {
+				auto_free char *label_str = kr_dname_text(label);
+				VERBOSE_MSG(qry,
+					"found cut: %s (rank 0%.2o return codes: DS %d, DNSKEY %d)\n",
+					label_str, rank, ret_ds, ret_dnskey);
+			}
+			ret = kr_ok();
+			break;
+		} /* else */
+
+		trie_clear(cut->nsset);
+		/* Subtract label from QNAME. */
+		if (!is_root) {
+			label = knot_wire_next_label(label, NULL);
+		} else {
+			ret = kr_error(ENOENT);
+			break;
+		}
+	}
+
+	kr_cache_commit(&ctx->cache);
+	mm_free(cut->pool, qname);
+	return ret;
+}
diff --git a/lib/zonecut.h b/lib/zonecut.h
new file mode 100644
index 0000000..56ca834
--- /dev/null
+++ b/lib/zonecut.h
@@ -0,0 +1,162 @@
+/*  Copyright (C) 2014-2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *  SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#pragma once
+
+#include "lib/cache/api.h"
+#include "lib/defines.h"
+#include "lib/generic/pack.h"
+#include "lib/generic/trie.h"
+
+
+struct kr_rplan;
+struct kr_context;
+
+/**
+ * Current zone cut representation.
+*/
+struct kr_zonecut {
+	knot_dname_t *name; /**< Zone cut name. */
+	knot_rrset_t* key;  /**< Zone cut DNSKEY. */
+	knot_rrset_t* trust_anchor; /**< Current trust anchor. */
+	struct kr_zonecut *parent; /**< Parent zone cut. */
+	trie_t *nsset;        /**< Map of nameserver => address_set (pack_t). */
+	knot_mm_t *pool;     /**< Memory pool. */
+};
+
+/**
+ * Populate root zone cut with SBELT.
+ * @param cut zone cut
+ * @param name
+ * @param pool
+ * @return 0 or error code
+ */
+KR_EXPORT
+int kr_zonecut_init(struct kr_zonecut *cut, const knot_dname_t *name, knot_mm_t *pool);
+
+/**
+ * Clear the structure and free the address set.
+ * @param cut zone cut
+ */
+KR_EXPORT
+void kr_zonecut_deinit(struct kr_zonecut *cut);
+
+/**
+ * Move a zonecut, transferring ownership of any pointed-to memory.
+ * @param to the target - it gets deinit-ed
+ * @param from the source - not modified, but shouldn't be used afterward
+ */
+KR_EXPORT
+void kr_zonecut_move(struct kr_zonecut *to, const struct kr_zonecut *from);
+
+/**
+ * Reset zone cut to given name and clear address list.
+ * @note This clears the address list even if the name doesn't change. TA and DNSKEY don't change.
+ * @param cut  zone cut to be set
+ * @param name new zone cut name
+ */
+KR_EXPORT
+void kr_zonecut_set(struct kr_zonecut *cut, const knot_dname_t *name);
+
+/**
+ * Copy zone cut, including all data. Does not copy keys and trust anchor.
+ * @param dst destination zone cut
+ * @param src source zone cut
+ * @return 0 or an error code; If it fails with kr_error(ENOMEM),
+ * it may be in a half-filled state, but it's safe to deinit...
+ * @note addresses for names in `src` get replaced and others are left as they were.
+ */
+KR_EXPORT
+int kr_zonecut_copy(struct kr_zonecut *dst, const struct kr_zonecut *src);
+
+/**
+ * Copy zone trust anchor and keys.
+ * @param dst destination zone cut
+ * @param src source zone cut
+ * @return 0 or an error code
+ */
+KR_EXPORT
+int kr_zonecut_copy_trust(struct kr_zonecut *dst, const struct kr_zonecut *src);
+
+/**
+ * Add address record to the zone cut.
+ *
+ * The record will be merged with existing data,
+ * it may be either A/AAAA type.
+ *
+ * @param cut    zone cut to be populated
+ * @param ns     nameserver name
+ * @param data   typically knot_rdata_t::data
+ * @param len    typically knot_rdata_t::len
+ * @return 0 or error code
+ */
+KR_EXPORT
+int kr_zonecut_add(struct kr_zonecut *cut, const knot_dname_t *ns, const void *data, int len);
+
+/**
+ * Delete nameserver/address pair from the zone cut.
+ * @param  cut
+ * @param  ns    name server name
+ * @param  data  typically knot_rdata_t::data
+ * @param  len   typically knot_rdata_t::len
+ * @return       0 or error code
+ */
+KR_EXPORT
+int kr_zonecut_del(struct kr_zonecut *cut, const knot_dname_t *ns, const void *data, int len);
+
+/**
+ * Delete all addresses associated with the given name.
+ * @param  cut
+ * @param  ns    name server name
+ * @return       0 or error code
+ */
+KR_EXPORT
+int kr_zonecut_del_all(struct kr_zonecut *cut, const knot_dname_t *ns);
+
+/**
+ * Find nameserver address list in the zone cut.
+ *
+ * @note This can be used for membership test, a non-null pack is returned
+ *       if the nameserver name exists.
+ *
+ * @param  cut
+ * @param  ns    name server name
+ * @return       pack of addresses or NULL
+ */
+KR_EXPORT KR_PURE
+pack_t *kr_zonecut_find(struct kr_zonecut *cut, const knot_dname_t *ns);
+
+/**
+ * Populate zone cut with a root zone using SBELT :rfc:`1034`
+ *
+ * @param ctx resolution context (to fetch root hints)
+ * @param cut zone cut to be populated
+ * @return 0 or error code
+ */
+KR_EXPORT
+int kr_zonecut_set_sbelt(struct kr_context *ctx, struct kr_zonecut *cut);
+
+/**
+ * Populate zone cut address set from cache.
+ *
+ * @param ctx       resolution context (to fetch data from LRU caches)
+ * @param cut       zone cut to be populated
+ * @param name      QNAME to start finding zone cut for
+ * @param qry       query for timestamp and stale-serving decisions
+ * @param secured   set to true if want secured zone cut, will return false if it is provably insecure
+ * @return 0 or error code (ENOENT if it doesn't find anything)
+ */
+KR_EXPORT
+int kr_zonecut_find_cached(struct kr_context *ctx, struct kr_zonecut *cut,
+			   const knot_dname_t *name, const struct kr_query *qry,
+			   bool * restrict secured);
+/**
+ * Check if any address is present in the zone cut.
+ *
+ * @param cut zone cut to check
+ * @return true/false
+ */
+KR_EXPORT
+bool kr_zonecut_is_empty(struct kr_zonecut *cut);
+