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diff --git a/bin/dig/host.rst b/bin/dig/host.rst new file mode 100644 index 0000000..2647d36 --- /dev/null +++ b/bin/dig/host.rst @@ -0,0 +1,193 @@ +.. Copyright (C) Internet Systems Consortium, Inc. ("ISC") +.. +.. SPDX-License-Identifier: MPL-2.0 +.. +.. This Source Code Form is subject to the terms of the Mozilla Public +.. License, v. 2.0. If a copy of the MPL was not distributed with this +.. file, you can obtain one at https://mozilla.org/MPL/2.0/. +.. +.. See the COPYRIGHT file distributed with this work for additional +.. information regarding copyright ownership. + +.. highlight: console + +.. iscman:: host +.. program:: host +.. _man_host: + +host - DNS lookup utility +------------------------- + +Synopsis +~~~~~~~~ + +:program:`host` [**-aACdlnrsTUwv**] [**-c** class] [**-N** ndots] [**-p** port] [**-R** number] [**-t** type] [**-W** wait] [**-m** flag] [ [**-4**] | [**-6**] ] [**-v**] [**-V**] {name} [server] + +Description +~~~~~~~~~~~ + +:program:`host` is a simple utility for performing DNS lookups. It is normally +used to convert names to IP addresses and vice versa. When no arguments +or options are given, :program:`host` prints a short summary of its +command-line arguments and options. + +``name`` is the domain name that is to be looked up. It can also be a +dotted-decimal IPv4 address or a colon-delimited IPv6 address, in which +case :program:`host` by default performs a reverse lookup for that address. +``server`` is an optional argument which is either the name or IP +address of the name server that :program:`host` should query instead of the +server or servers listed in ``/etc/resolv.conf``. + +Options +~~~~~~~ + +.. option:: -4 + + This option specifies that only IPv4 should be used for query transport. See also the :option:`-6` option. + +.. option:: -6 + + This option specifies that only IPv6 should be used for query transport. See also the :option:`-4` option. + +.. option:: -a + + The :option:`-a` ("all") option is normally equivalent to :option:`-v` :option:`-t ANY <-t>`. It + also affects the behavior of the :option:`-l` list zone option. + +.. option:: -A + + The :option:`-A` ("almost all") option is equivalent to :option:`-a`, except that RRSIG, + NSEC, and NSEC3 records are omitted from the output. + +.. option:: -c class + + This option specifies the query class, which can be used to lookup HS (Hesiod) or CH (Chaosnet) + class resource records. The default class is IN (Internet). + +.. option:: -C + + This option indicates that :iscman:`named` should check consistency, meaning that :program:`host` queries the SOA records for zone + ``name`` from all the listed authoritative name servers for that + zone. The list of name servers is defined by the NS records that are + found for the zone. + +.. option:: -d + + This option prints debugging traces, and is equivalent to the :option:`-v` verbose option. + +.. option:: -l + + This option tells :iscman:`named` to list the zone, meaning the :program:`host` command performs a zone transfer of zone + ``name`` and prints out the NS, PTR, and address records (A/AAAA). + + Together, the :option:`-l` :option:`-a` options print all records in the zone. + +.. option:: -N ndots + + This option specifies the number of dots (``ndots``) that have to be in ``name`` for it to be + considered absolute. The default value is that defined using the + ``ndots`` statement in ``/etc/resolv.conf``, or 1 if no ``ndots`` statement + is present. Names with fewer dots are interpreted as relative names, + and are searched for in the domains listed in the ``search`` or + ``domain`` directive in ``/etc/resolv.conf``. + +.. option:: -p port + + This option specifies the port to query on the server. The default is 53. + +.. option:: -r + + This option specifies a non-recursive query; setting this option clears the RD (recursion + desired) bit in the query. This means that the name server + receiving the query does not attempt to resolve ``name``. The :option:`-r` + option enables :program:`host` to mimic the behavior of a name server by + making non-recursive queries, and expecting to receive answers to + those queries that can be referrals to other name servers. + +.. option:: -R number + + This option specifies the number of retries for UDP queries. If ``number`` is negative or zero, + the number of retries is silently set to 1. The default value is 1, or + the value of the ``attempts`` option in ``/etc/resolv.conf``, if set. + +.. option:: -s + + This option tells :iscman:`named` *not* to send the query to the next nameserver if any server responds + with a SERVFAIL response, which is the reverse of normal stub + resolver behavior. + +.. option:: -t type + + This option specifies the query type. The ``type`` argument can be any recognized query type: + CNAME, NS, SOA, TXT, DNSKEY, AXFR, etc. + + When no query type is specified, :program:`host` automatically selects an + appropriate query type. By default, it looks for A, AAAA, and MX + records. If the :option:`-C` option is given, queries are made for SOA + records. If ``name`` is a dotted-decimal IPv4 address or + colon-delimited IPv6 address, :program:`host` queries for PTR records. + + If a query type of IXFR is chosen, the starting serial number can be + specified by appending an equals sign (=), followed by the starting serial + number, e.g., :option:`-t IXFR=12345678 <-t>`. + +.. option:: -T, -U + + This option specifies TCP or UDP. By default, :program:`host` uses UDP when making queries; the + :option:`-T` option makes it use a TCP connection when querying the name + server. TCP is automatically selected for queries that require + it, such as zone transfer (AXFR) requests. Type ``ANY`` queries default + to TCP, but can be forced to use UDP initially via :option:`-U`. + +.. option:: -m flag + + This option sets memory usage debugging: the flag can be ``record``, ``usage``, or + ``trace``. The :option:`-m` option can be specified more than once to set + multiple flags. + +.. option:: -v + + This option sets verbose output, and is equivalent to the :option:`-d` debug option. Verbose output + can also be enabled by setting the ``debug`` option in + ``/etc/resolv.conf``. + +.. option:: -V + + This option prints the version number and exits. + +.. option:: -w + + This option sets "wait forever": the query timeout is set to the maximum possible. See + also the :option:`-W` option. + +.. option:: -W wait + + This options sets the length of the wait timeout, indicating that :iscman:`named` should wait for up to ``wait`` seconds for a reply. If ``wait`` is + less than 1, the wait interval is set to 1 second. + + By default, :program:`host` waits for 5 seconds for UDP responses and 10 + seconds for TCP connections. These defaults can be overridden by the + ``timeout`` option in ``/etc/resolv.conf``. + + See also the :option:`-w` option. + +IDN Support +~~~~~~~~~~~ + +If :program:`host` has been built with IDN (internationalized domain name) +support, it can accept and display non-ASCII domain names. :program:`host` +appropriately converts character encoding of a domain name before sending +a request to a DNS server or displaying a reply from the server. +To turn off IDN support, define the ``IDN_DISABLE`` +environment variable. IDN support is disabled if the variable is set +when :program:`host` runs. + +Files +~~~~~ + +``/etc/resolv.conf`` + +See Also +~~~~~~~~ + +:iscman:`dig(1) <dig>`, :iscman:`named(8) <named>`. |