Adding upstream version 2.2.0.upstream/2.2.0upstream

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

25 files changed, 6780 insertions, 0 deletions

diff --git a/doc/examples/kea4/advanced.json b/doc/examples/kea4/advanced.json
new file mode 100644
index 0000000..4b25f46
--- /dev/null
+++ b/doc/examples/kea4/advanced.json
@@ -0,0 +1,204 @@
+// This is an example configuration file for DHCPv4 server in Kea.
+// It covers some of the more advanced features. This file may not be coherent
+// as its main purpose is to demonstrate the features. They don't necessarily
+// have to make sense used together.
+
+// The new parser supports 3 comment styles:
+
+// This is C++ style.
+
+# This is a bash style.
+
+/* This is a C style comment. */
+
+/* C style comment
+   can span
+   multiple lines */
+
+{ "Dhcp4":
+
+{
+    // Kea is told to listen on eth0 interface only.
+    "interfaces-config": {
+        "interfaces": [ "eth0" ],
+
+        // This specifies what type of socket Kea uses. Currently supported
+        // are 'raw' (which is the default) and 'udp'. Raw has the benefit
+        // of receiving all traffic every time and a downside of bypassing
+        // all firewall rules and having marginally bigger performance impact.
+        // 'udp' is generally better if you have only relayed traffic. Kea
+        // than opens up normal UDP socket and the kernel does all the
+        // Ethernet/IP stack processing.
+        "dhcp-socket-type": "udp",
+
+        // Typically the DHCP server will send its response back on the same
+        // interface the query came in. This is the default ("same-as-inbound").
+        // However, sometimes it is useful to have the ability to send the
+        // packet as plain UDP packet and let the kernel and the routing tables
+        // determine the right interface ("use-routing"). This option  only works
+        // for "dhcp-socket-type" set to "udp" and is ignored otherwise.
+        "outbound-interface": "use-routing",
+
+        // This makes interfaces to be re-detected at each (re-)configuration.
+        // By default it is true.
+        "re-detect": true
+    },
+
+    "sanity-checks": {
+        // This parameter determines what to do when a new lease appears in the
+        // system (i.e. either is read from disk during memfile startup or is
+        // added via lease commands). There are five modes supported:
+        // none - do nothing, accept them as is
+        // warn - if subnet-id problems are detected, print a warning, but
+        //        otherwise load the lease as is. This is the default value.
+        // fix - attempt to fix the lease by finding appropriate subnet-id value.
+        //       if there is no suitable subnet, the lease is loaded as is.
+        // fix-del - attempt to fix the lease by finding appropriate subnet-id
+        //           value. If there is no suitable subnet, the lease is deleted.
+        // del - delete leases that have incorrect subnet-id values.
+        "lease-checks": "fix-del"
+    },
+
+    // Option 43 last resort definition can make well-formed messages
+    // to be rejected because they use not compatible "raw" value,
+    // and different vendors may define different sub-options.
+    // The option definition should be applied to avoid these problems,
+    // for instance by defining at the global scope the option as binary.
+    // In client-classes the option may be redefined as carrying vendor
+    // dependent sub-options.
+    "option-def": [ {
+        "name": "vendor-encapsulated-options",
+        "code": 43,
+        "type": "binary"
+    } ],
+
+    // We need to specify the database used to store leases. As of
+    // June 2022, three database backends are supported: MySQL,
+    // PostgreSQL and the in-memory database, Memfile.
+    // We'll use memfile  because it doesn't require any prior set up.
+    // For memfile, it's important to always specify lfc-interval, so
+    // the lease file would not grow without bounds and be sanitized
+    // once per hour.
+    "lease-database": {
+        "type": "memfile",
+        "lfc-interval": 3600
+    },
+
+    // This defines a control socket. If defined, Kea will open a UNIX socket
+    // and will listen for incoming commands. See section 15 of the Kea User's
+    // Guide for list of supported commands.
+    "control-socket": {
+        "socket-type": "unix",
+        "socket-name": "/tmp/kea4-ctrl-socket"
+    },
+
+    // Addresses will be assigned with a lifetime of 4000 seconds.
+    // The client is told to start renewing after 1000 seconds. If the server
+    // does not respond within 2000 seconds of the lease being granted, client
+    // is supposed to start REBIND procedure (emergency renewal that allows
+    // switching to a different server).
+    "valid-lifetime": 4000,
+    "renew-timer": 1000,
+    "rebind-timer": 2000,
+
+    // RFC6842 says that the server is supposed to echo back client-id option.
+    // However, some older clients do not support this and are getting confused
+    // when they get their own client-id. Kea can disable RFC6842 support.
+    "echo-client-id": false,
+
+    // Some clients don't use stable client identifier, but rather
+    // generate them during each boot. This may cause a client that
+    // reboots frequently to get multiple leases, which may not be
+    // desirable. As such, sometimes admins prefer to tell their DHCPv4
+    // server to ignore client-id value altogether and rely exclusively
+    // on MAC address. This is a parameter that is defined globally, but
+    // can be overridden on a subnet level.
+    "match-client-id": true,
+
+    // By default, Kea ignores requests by clients for unknown IP addresses,
+    // because other non-cooperating DHCP servers could reside on the same
+    // network (RFC 2131). This parameter is defined globally, but can be
+    // overridden on a subnet level
+    "authoritative": false,
+
+    // The following list defines subnets. Each subnet consists of at
+    // least subnet and pool entries. One extra feature that requires
+    // some explanation is user-context. This is a structure that you can
+    // define in subnets, pools and others. It is parsed by Kea, but not
+    // used directly.  It is intended to keep anything you may want to
+    // put there - comments, extra designations, floor or department
+    // names etc. These structures will be made available to Kea hooks.
+    // A comment entry is translated into a user-context with a
+    // "comment" property so you can include comments inside the
+    // configuration itself.
+    "subnet4": [
+        {
+            "pools": [ {
+                "pool":  "192.0.2.1 - 192.0.2.200",
+                "user-context": { "info": "what a large pool" }
+            } ],
+            "subnet": "192.0.2.0/24",
+            "user-context": {
+                "comment": "Our first subnet!"
+            }
+            // Equivalent using smart parser
+            // "comment": "Our first subnet!"
+        },
+        {
+            // This particular subnet has match-client-id value changed.
+            // This causes Kea to ignore client-id values in this subnet
+            // and rely exclusively on MAC addresses.
+            "pools": [ { "pool": "192.0.3.100 - 192.0.3.200" } ],
+            "subnet": "192.0.3.0/24",
+            "match-client-id": false
+        },
+        {
+            "pools": [ { "pool": "192.0.4.1 - 192.0.4.254" } ],
+            "subnet": "192.0.4.0/24",
+
+            // Sometimes the relay may use an IPv4 address that does
+            // not match the subnet. This is discouraged, but there are
+            // valid cases when it makes sense. One case is when there
+            // is a shared subnet.
+            "relay": {
+                "ip-address": "192.168.1.1"
+            }
+        },
+        {
+            // This particular subnet has the authoritative value changed.
+            // This causes Kea to reply to requests for unknown IP addresses
+            // with a DHCPNAK message.
+            "pools": [ { "pool": "192.0.5.100 - 192.0.5.200" } ],
+            "subnet": "192.0.5.0/24",
+            "authoritative": true
+        }
+    ],
+
+    // The following configures logging. It assumes that messages with
+    // at least informational level (info, warn, error and fatal) should
+    // be logged to stdout.
+    "loggers": [
+          {
+            "name": "kea-dhcp4",
+              "output_options": [
+                  {
+                      "output": "stdout",
+                      // Several additional parameters are possible in addition
+                      // to the typical output. Flush determines whether logger
+                      // flushes output to a file. Maxsize determines maximum
+                      // filesize before the file is being rotated. maxver
+                      // specifies the maximum number of rotated files being
+                      // kept.
+                      "flush": true,
+                      "maxsize": 204800,
+                      "maxver": 4,
+                      // We use pattern to specify custom log message layout
+                      "pattern": "%d{%y.%m.%d %H:%M:%S.%q} %-5p [%c/%i] %m\n"
+                  }
+              ],
+              "severity": "INFO"
+          }
+      ]
+  }
+
+}
diff --git a/doc/examples/kea4/all-keys-netconf.json b/doc/examples/kea4/all-keys-netconf.json
new file mode 100644
index 0000000..baa1594
--- /dev/null
+++ b/doc/examples/kea4/all-keys-netconf.json
@@ -0,0 +1,1139 @@
+// WARNING: This example configuration is not meant for production use.
+// The Kea DHCPv4 server will refuse this configuration because it contains
+// mutually exclusive configuration parameters.
+//
+// The primary purpose of the example file is to provide a comprehensive
+// list of parameters supported by Kea DHCPv4 server along with the brief
+// description of each parameter.
+//
+// This stable version is used for YANG as we do not want to update code
+// and models each time a keyword is added to the syntax.
+{
+    // Kea DHCPv4 server configuration begins here.
+    "Dhcp4": {
+
+        // Global authoritative flag to handle requests by clients for
+        // unknown IP addresses (ignore if disabled, NAK if enabled).
+        "authoritative": false,
+
+        // Global bootfile name to be set in the 'file' field.
+        "boot-file-name": "/dev/null",
+
+        // Ordered list of client classes used by the DHCPv4 server.
+        "client-classes": [
+            {
+                // Class specific bootfile name to be set in the 'file' field.
+                "boot-file-name": "/tmp/bootfile.efi",
+
+                // Class name.
+                "name": "phones_server1",
+
+                // Class specific next server address to use in bootstrap, which
+                // is set in 'siaddr' field.
+                "next-server": "10.2.3.4",
+
+                // Class specific DHCPv4 options list.
+                "option-data": [],
+
+                // Class specific DHCPv4 option definitions, i.e. custom formats
+                // specified for non-standard options.
+                "option-def": [],
+
+                // Class specific optional server hostname, which is set in
+                // 'sname' field.
+                "server-hostname": "",
+
+                // Class selection expression. The DHCP packet is assigned to this
+                // class when the given expression evaluates to true.
+                "test": "member('HA_server1')",
+
+                // Class valid lifetime.
+                "valid-lifetime": 6000,
+
+                // Class min valid lifetime.
+                "min-valid-lifetime": 4000,
+
+                // Class max valid lifetime.
+                "max-valid-lifetime": 8000
+            },
+            {
+                // Default value of the class specific bootfile name. Empty name
+                // means that the bootfile name is unspecified.
+                "boot-file-name": "",
+
+                // Second class name.
+                "name": "phones_server2",
+
+                // Default value of the class specific next server address. The
+                // zero IPv4 address means that it is unspecified.
+                "next-server": "0.0.0.0",
+
+                // Class specific DHCPv4 options list.
+                "option-data": [],
+
+                // Class specific DHCPv4 option definitions, i.e. custom formats
+                // specified for non-standard options.
+                "option-def": [],
+
+                // Class specific optional server hostname, which is set in
+                // 'sname' field.
+                "server-hostname": "",
+
+                // Class selection expression. The DHCP packet is assigned to this
+                // class when the given expression evaluates to true.
+                "test": "member('HA_server2')"
+            },
+
+            {
+                // Third class name.
+                "name": "late",
+
+                // Boolean flag indicating that the class expression is only evaluated
+                // when the class is required, e.g. selected address pool configuration
+                // includes this class name in its "require-client-classes" list. The
+                // default value false means that the class test expression must
+                // always be evaluated.
+                "only-if-required": true,
+
+                // Class selection expression.
+                "test": "member('ALL')"
+            }
+        ],
+
+        // Parameters for triggering behaviors compatible with broken or
+        // non-compliant clients, relays or other agents
+        "compatibility": {
+            // Parse options more leniently where fields can be deduced
+            // deterministically even if against RFC or common practice.
+            "lenient-option-parsing": true
+        },
+
+        // Command control socket configuration parameters for Kea DHCPv4 server.
+        "control-socket": {
+            // Location of the unix domain socket file the DHCPv4 server uses
+            // to receive control commands from the Kea Control Agent or the
+            // local server administrator.
+            "socket-name": "/tmp/kea4-ctrl-socket",
+
+            // Control socket type used by the Kea DHCPv4 server. The 'unix'
+            // socket is currently the only supported type.
+            "socket-type": "unix"
+        },
+
+        // Specifies a prefix to be prepended to the generated Client FQDN.
+        // It may be specified at the global, shared-network and subnet levels.
+        "ddns-generated-prefix": "myhost",
+
+        // Boolean flag indicating that server should ignore DHCP client
+        // wishes to update DNS on its own. With that flag set to true
+        // the server will send DNS updates for both forward and
+        // reverse DNS data. The default value is false, which indicates
+        // that the server will delegate DNS update to the client when
+        // requested. It may be specified at the global, shared-network
+        // and subnet levels.
+        "ddns-override-client-update": false,
+
+        // Boolean flag indicating that the server should override DHCP
+        // client's wish to not update the DNS. With this parameter
+        // set to true the server will send DNS update even when
+        // the client requested no update.  It may be specified at the
+        // global, shared-network and subnet levels.
+        "ddns-override-no-update": false,
+
+        // Suffix appended to the partial name sent to the DNS. The
+        // default value is an empty string which indicates that no
+        // suffix is appended.  It may be specified at the global,
+        // shared-network and subnet levels.
+        "ddns-qualifying-suffix": "",
+
+        // Enumeration specifying whether the server should honor
+        // hostname or Client FQDN sent by the client or replace
+        // this name. The acceptable values are: "never" (use the
+        // name the client sent), "always" (replace the name the
+        // client sent), "when-present" (replace the name the client
+        // sent, but do not generate one when the client didn't sent
+        // the name), "when-not-present" (generate the name when
+        // client didn't send one, otherwise leave the name the
+        // client sent). The default value is "never".  It may be
+        // specified at the global, shared-network and subnet levels.
+        "ddns-replace-client-name": "never",
+
+        // Boolean flag which enables or disables the DDNS updating. It
+        // defaults to true.  It may be specified at the global, shared-
+        // network and subnet levels. It works in conjunction with
+        // dhcp-ddns:enable-updates which must be true to enable connectivity
+        // to kea-dhcp-ddns.
+        "ddns-send-updates": true,
+
+        // Boolean flag, which when true instructs the server to always
+        // update DNS when leases are renewed, even if the DNS information
+        // has not changed.  The server's default behavior (i.e. flag is false)
+        // is to only update DNS if the DNS information has changed.  It
+        // may be specified at the global, shared-network and subnet levels.
+        "ddns-update-on-renew": true,
+
+        // Boolean flag, which is passed to kea-dhcp-ddns with each DDNS
+        // update request to indicate whether or not DNS update conflict
+        // resolution as described in RFC 4703 should be employed for the
+        // given update request.  The default value for this flag is true.
+        // It may be specified at the global, shared-network and subnet levels.
+        "ddns-use-conflict-resolution": true,
+
+        // Time in seconds specifying how long a declined lease should be
+        // excluded from DHCP assignments. The default value is 24 hours.
+        "decline-probation-period": 86400,
+
+        // Name Change Requests forwarding configuration for Kea DHCPv4 server.
+        // NCRs are sent to Kea D2 module to update DNS upon allocation of the
+        // DHCP leases.
+        "dhcp-ddns": {
+            // Boolean flag indicating if Kea DHCPv4 server should connect to
+            // kea-dhcp-ddns.  This must be true for NCRs to be created and
+            // sent to kea-dhcp-ddns. By default NCRs are not generated.
+            "enable-updates": false,
+
+            // Specifies maximum number of NCRs to queue waiting to be sent
+            // to Kea D2 server.
+            "max-queue-size": 1024,
+
+            // Packet format to use when sending NCRs to Kea D2 server.
+            // Currently, only JSON format is supported.
+            "ncr-format": "JSON",
+
+            // Socket protocol to use when sending NCRs to D2. Currently,
+            // only UDP is supported.
+            "ncr-protocol": "UDP",
+
+            // IP address that Kea DHCPv4 server should use to send
+            // NCRs to D2. Default value of zero indicates that Kea
+            // should pick suitable address.
+            "sender-ip": "0.0.0.0",
+
+            // Port number that Kea DHCPv4 server should use to send
+            // NCRs to D2. Default value of zero indicates that Kea
+            // should pick suitable port.
+            "sender-port": 0,
+
+            // IP address on which D2 listens for NCRs.
+            "server-ip": "127.0.0.1",
+
+            // Port number on which D2 listens for NCRs.
+            "server-port": 53001,
+
+            // The follow parameters are DEPRECATED.  They have been
+            // replaced with parameters that may be set at the global,
+            // shared-network, and subnet4 scopes.  They are listed here
+            // as configuration parsing still accepts them.  Eventually
+            // support for them will be removed.
+            "generated-prefix": "myhost",
+            "hostname-char-replacement": "x",
+            "hostname-char-set": "[^A-Za-z0-9.-]",
+            "override-client-update": false,
+            "override-no-update": false,
+            "qualifying-suffix": "",
+            "replace-client-name": "never"
+        },
+
+        // Specifies the first of the two consecutive ports of the UDP
+        // sockets used for communication between DHCPv6 and DHCPv4
+        // servers. See RFC 7341.
+        "dhcp4o6-port": 6767,
+
+        // Boolean flag indicating whether or not the Kea DHCPv4 server
+        // should send back Client Identifier option in its responses.
+        // The default value is true which indicates that the option
+        // must be sent back if the client included it. The false
+        // value instructs the server to not send this option for
+        // backward compatibility with older DHCP specifications which
+        // stated that Client Identifier must not be sent back.
+        "echo-client-id": true,
+
+        // Collection of Kea DHCPv4 server parameters configuring how
+        // the server should process expired DHCP leases.
+        "expired-leases-processing": {
+            // Specifies the number of seconds since last removal of
+            // the expired leases when next removal should occur.
+            "flush-reclaimed-timer-wait-time": 25,
+
+            // Specifies the time period in seconds to keep expired
+            // leases in the lease database (lease affinity).
+            "hold-reclaimed-time": 3600,
+
+            // Specifies the maximum number of expired leases that can be
+            // processed in a single attempt to clean up the lease
+            // database from the expired leases. If there are more
+            // expired leases, they will be processed during the next
+            // cleanup attempt.
+            "max-reclaim-leases": 100,
+
+            // Specifies the maximum time in milliseconds that the single
+            // attempt to cleanup the lease database from the expired
+            // leases may take.
+            "max-reclaim-time": 250,
+
+            // Specifies the time period in seconds since last attempt
+            // to process expired leases to initiate the next attempt.
+            "reclaim-timer-wait-time": 10,
+
+            // Specifies the maximum number of expired leases processing
+            // cycles which didn't result in full cleanup of the lease
+            // database from the expired leases, after which a
+            // warning message is issued.
+            "unwarned-reclaim-cycles": 5
+        },
+
+        // List of hooks libraries and their specific configuration parameters
+        // to be loaded by Kea DHCPv4 server.
+        "hooks-libraries": [
+            {
+                // Location of the hooks library to be loaded.
+                "library": "/opt/lib/kea/hooks/libdhcp_lease_cmds.so",
+
+                // Hook library specific configuration parameters.
+                "parameters": { }
+            }
+        ],
+
+        // List of access credentials to external sources of IPv4 reservations,
+        "hosts-databases": [
+            {
+                // Name of the database to connect to.
+                "name": "keatest",
+
+                // Host on which the database resides.
+                "host": "localhost",
+
+                // Database password.
+                "password": "keatest",
+
+                // Port on which the database is available.
+                "port": 3306,
+
+                // Type of the database, e.g. "mysql", "postgresql".
+                "type": "mysql",
+
+                // User name to be used to access the database.
+                "user": "keatest",
+
+                // Read only mode.
+                "readonly": false,
+
+                // Next entries are for the OpenSSL support in MySQL.
+
+                // Trust anchor aka certificate authority file or directory.
+                "trust-anchor": "my-ca",
+
+                // Client certificate file name.
+                "cert-file": "my-cert",
+
+                // Private key file name.
+                "key-file": "my-key",
+
+                // Cipher list (see the OpenSSL ciphers command manual).
+                "cipher-list": "AES"
+            },
+            {
+                // Name of the database to connect to.
+                "name": "keatest",
+
+                // Host on which the database resides.
+                "host": "localhost",
+
+                // Database password.
+                "password": "keatest",
+
+                // Port on which the database is available.
+                "port": 5432,
+
+                // Type of the database, e.g. "mysql", "postgresql".
+                "type": "postgresql",
+
+                // User name to be used to access the database.
+                "user": "keatest",
+
+                // Connection reconnect wait time.
+                // This parameter governs how long Kea waits before attempting
+                // to reconnect. Expressed in milliseconds. The default is 0
+                // (disabled) for MySQL and PostgreSQL.
+                "reconnect-wait-time": 3000,
+
+                // Connection maximum reconnect tries.
+                "max-reconnect-tries": 3,
+
+                // Action to take when connection recovery fails.
+                // Supported values: stop-retry-exit, serve-retry-exit,
+                // serve-retry-continue
+                "on-fail": "stop-retry-exit",
+
+                // Connection connect timeout.
+                "connect-timeout": 100
+            }
+        ],
+
+        // List of host reservation identifier types to be used by the
+        // Kea DHCPv4 server to fetch static reservations for the
+        // DHCP clients. All identifiers are used by default, which
+        // means that the server will issue multiple queries to the
+        // database to find if there is a reservation for the particular
+        // client. If the particular deployment uses only subset, e.g.
+        // one, identifier type, this identifier should be only listed
+        // here to prevent unnecessary queries to the database.
+        "host-reservation-identifiers": [
+            "hw-address",
+            "duid",
+            "circuit-id",
+            "client-id",
+            "flex-id"
+        ],
+
+        // Specifies configuration of interfaces on which the Kea DHCPv4
+        // server is listening to the DHCP queries.
+        "interfaces-config": {
+            // Specifies whether the server should use "udp" socket or
+            // "raw" sockets to listen to the DHCP traffic. The "raw"
+            // sockets are useful when direct DHCP traffic is being
+            // received.
+            "dhcp-socket-type": "udp",
+
+            // Specifies a list of interfaces on which the Kea DHCPv4
+            // server should listen to the DHCP requests.
+            "interfaces": [
+                "eth0"
+            ],
+
+            // Enumeration which indicates what interface should be used
+            // to send DHCP response to the client. The default value is
+            // "same-as-inbound" which indicates that the response should
+            // be sent via the interface on which the client's query
+            // was received. The "use-routing" value indicates that the
+            // Kea server should use kernel's routing table to find the
+            // suitable interface.
+            "outbound-interface": "same-as-inbound",
+
+            // Boolean flag indicating if the available interfaces should
+            // be re-detected upon server reconfiguration. The default value
+            // is true which means that the interfaces are always
+            // re-detected.
+            "re-detect": true,
+
+            // Kea tries to bind the service sockets during initialization. It may
+            // fail due to a port being already opened or misconfiguration. Kea can
+            // suppress these errors and only logs them. This flag prevents starting
+            // the DHCP server without binding all sockets. If unspecified, it
+            // defaults to false.
+            "service-sockets-require-all": true,
+
+            // Kea tries to bind the service sockets during initialization. This
+            // option specifies how many times binding to interface will be retried.
+            // The default value is 0 which means that the operation will not be
+            // repeated.
+            "service-sockets-max-retries": 5,
+
+            // The time interval in milliseconds to wait before the next attempt to
+            // retry opening a service socket.
+            "service-sockets-retry-wait-time": 5000
+        },
+
+        // Boolean parameter which controls whether an early global host
+        // reservations lookup should be performed. This lookup takes place
+        // before subnet selection and when a global reservation is found
+        // with some client classes, it triggers a second phase classification.
+        // It can also be used to drop queries using host reservations as a
+        // decision table indexed by reservation identifiers.
+        "early-global-reservations-lookup": true,
+
+        // Boolean parameter which controls DHCP server's behavior with respect
+        // to creating host reservations for the same IP address. By default
+        // this flag is set to true in which case the server prevents creation
+        // of multiple host reservations for the same IP address. When this
+        // parameter is set to false, the server allows for creating multiple
+        // reservations for the same IP address within a subnet. This setting
+        // is useful in deployments in which a given host may be communicating
+        // with a DHCP server over multiple interfaces and depending on the
+        // chosen interface different MAC address (or other identifier) will
+        // be used to identify the host. Note that some host backends do not
+        // support the mode in which multiple reservations for the same IP
+        // address are used. If these backends are in use and this setting
+        // is attempted a configuration error will occur. The MySQL and
+        // PostgreSQL backends do support this mode.
+        "ip-reservations-unique": true,
+
+        /// Boolean parameter which controls whether host reservations lookup
+        /// should be performed before lease lookup. This parameter has effect
+        /// only when multi-threading is disabled. When multi-threading is
+        /// enabled, host reservations lookup is always performed first to avoid
+        /// lease lookup resource locking.
+        "reservations-lookup-first": true,
+
+        // Specifies credentials to access lease database.
+        "lease-database": {
+            // memfile backend specific parameter specifying the interval
+            // in seconds at which lease file should be cleaned up (outdated
+            // lease entries are removed to prevent lease file from growing
+            // infinitely).
+            "lfc-interval": 3600,
+
+            // Maximum number of lease file read errors allowed before
+            // loading the file is abandoned.  Defaults to 0 (no limit).
+            "max-row-errors": 100,
+
+            // Name of the lease file. In case of database it specifies the
+            // database name.
+            "name": "/tmp/kea-dhcp4.csv",
+
+            // memfile specific parameter indicating whether leases should
+            // be saved on persistent storage (disk) or not. The true value
+            // is the default and it indicates that leases are stored in the
+            // persistent storage. This setting must be used in production.
+            // The false value should only be used for testing purposes
+            // because non stored leases will be lost upon Kea server restart.
+            "persist": true,
+
+            // Lease database backend type, i.e. "memfile", "mysql" or
+            // "postgresql".
+            "type": "memfile"
+        },
+
+        // Boolean value indicating if the Kea DHCPv4 server should use client
+        // identifier value sent by the client or ignore it. The default value
+        // is true which indicate that the server should use client identifier
+        // and that it takes precedence over client's MAC address. In deployments
+        // where MAC address should take precedence this value can be set to
+        // false, in which case the clients will be identified by MAC address.
+        // This is specifically useful when clients don't generate unique
+        // identifiers or these identifiers are not stable etc.
+        "match-client-id": false,
+
+        // Global value of the next server address set in 'siaddr' field.
+        // The global value may be overridden in lower level configuration
+        // scopes.
+        "next-server": "192.0.2.123",
+
+        // Global value which limits the number of client packets (e.g.
+        // DHCPREQUESTs) that may be parked while waiting for hook library
+        // work to complete, prior to a response (e.g. DHCPACK) being sent
+        // back to the client.  A typical example is when kea-dhcp4 parks a
+        // DHCPREQUEST while it sends the lease update(s) to its HA peer(s).
+        // The packet is unparked once the update(s) have been acknowledged.
+        // This value limits the number of packets that can be held pending
+        // the updates. In times of heavy client traffic, this value can keep
+        // kea-dhcp4 from building an insurmountable backlog of updates.
+        "parked-packet-limit": 128,
+
+        // List of global DHCP options that Kea DHCPv4 server assigns to the
+        // clients.
+        "option-data": [
+            {
+                // Boolean flag indicating if the given option is always
+                // send in response or only when requested. The default
+                // value of false indicates that it is only sent when
+                // requested.
+                "always-send": false,
+
+                // Option code. It is not required if the option name is
+                // provided.
+                "code": 6,
+
+                // Boolean value indicating whether the option data specified
+                // in the "data" field is specified as a string of hexadecimal
+                // digits or in human readable CSV format.
+                "csv-format": true,
+
+                // Option data to be stored in the option payload.
+                "data": "192.0.3.1, 192.0.3.2",
+
+                // Option name. It is not required of the option code is
+                // provided.
+                "name": "domain-name-servers",
+
+                // Option space. The default is the "dhcp4" option space which
+                // groups top level DHCPv4 options.
+                "space": "dhcp4"
+            }
+        ],
+
+        // List of global option definitions, i.e. option formats, that the
+        // Kea DHCPv4 server is using.
+        "option-def": [
+            {
+                // Boolean flag indicating if the option definition comprises
+                // an array of values of some type, e.g. array of IPv4 addresses.
+                // The default value of false means that the option does not
+                // comprise an array of values.
+                "array": false,
+
+                // Option code.
+                "code": 6,
+
+                // Holds a name of the option space encapsulated by this option.
+                // All options that belong to this option space will be sent
+                // as sub-options of this option. Empty string means that this
+                // option doesn't encapsulate any option.
+                "encapsulate": "",
+
+                // Option name.
+                "name": "my-option",
+
+                // Specifies the types of fields within the option if the option
+                // is said to be a "record" (see "type"). in this particular example
+                // this option comprises two fields, 1 byte and 2 bytes long.
+                "record-types": "uint8, uint16",
+
+                // Name of the option space to which this option belongs.
+                "space": "my-space",
+
+                // Option type. All possible types are listed in the Kea
+                // Administrator Reference Manual.
+                "type": "record"
+            }
+        ],
+
+        // Global value for the rebind timer, i.e. the time after which the
+        // DHCP client enters rebind state if it fails to renew the lease.
+        "rebind-timer": 40,
+
+        // Global value for the renew timer, i.e. the timer after which the
+        // DHCP client renews the lease.
+        "renew-timer": 30,
+
+        // Global value to store extended information (e.g. relay agent
+        // information) with each lease.
+        "store-extended-info": true,
+
+        // Statistics keep some samples per observation point.
+        // There are two default values: maximum count and maximum age.
+        // Set the maximum count to zero disables it.
+        "statistic-default-sample-count": 0,
+
+        // When the maximum count is 0 the maximum age (in seconds) applies.
+        "statistic-default-sample-age": 60,
+
+        // Multi-threading parameters.
+        "multi-threading": {
+            // By default Kea processes packets on a single thread (default
+            // 'false' value for this option). To enable multi-threading, this
+            // option can be set ('true' value).
+            "enable-multi-threading": false,
+
+            // When multi-threading is enabled, Kea will process packets on a
+            // number of multiple threads configurable through this option. The
+            // value must be a positive integer (0 means auto detect).
+            "thread-pool-size": 0,
+
+            // When multi-threading is enabled, Kea will read packets from the
+            // interface and append a working item to the thread pool. This
+            // option configures the maximum number of items that can be queued.
+            // The value must be a positive integer (0 means unlimited).
+            "packet-queue-size": 0
+        },
+
+        // Governs how the Kea DHCPv4 server should deal with the invalid
+        // data received from the client.
+        "sanity-checks": {
+            // Specifies how the Kea DHCPv4 server should behave when invalid
+            // data is read for a lease from the lease file. The following
+            // values are supported "none" (don't attempt to correct the
+            // lease information), "warn" (print a warning for subnet-id
+            // related inconsistencies), "fix" (correct the subnet id by
+            // trying to find the suitable subnet), "fix-del" (similar
+            // to "fix" but delete the lease if no suitable subnet found),
+            // "del" (delete the lease if the lease has invalid subnet
+            // identifier value).
+            "lease-checks": "warn"
+        },
+
+        // List of shared networks used by Kea DHCPv4 server. The shared
+        // networks group subnets together.
+        "shared-networks": [
+            {
+                // Shared network level authoritative flag.
+                "authoritative": false,
+
+                // Shared network level bootfile name.
+                "boot-file-name": "/dev/null",
+
+                // Restricts this shared network to allow only clients
+                // that belong to the particular client class. If an
+                // empty string is provided, no restriction is applied.
+                "client-class": "",
+
+                // Shared network level value. See description at the global level.
+                "ddns-generated-prefix": "myhost",
+
+                // Shared network level value. See description at the global level.
+                "ddns-override-client-update": false,
+
+                // Shared network level value. See description at the global level.
+                "ddns-override-no-update": false,
+
+                // Shared network level value. See description at the global level.
+                "ddns-qualifying-suffix": "",
+
+                // Shared network level value. See description at the global level.
+                "ddns-replace-client-name": "never",
+
+                // Shared network level value. See description at the global level.
+                "ddns-send-updates": true,
+
+                // Shared network level value. See description at the global level.
+                "ddns-update-on-renew": true,
+
+                // Shared network level value. See description at the global level.
+                "ddns-use-conflict-resolution": true,
+
+                // Shared network level value. See description at the global level.
+                "hostname-char-replacement": "x",
+
+                // Shared network level value. See description at the global level.
+                "hostname-char-set": "[^A-Za-z0-9.-]",
+
+                // Specifies that this shared network is selected for the
+                // requests received on the particular interface.
+                "interface": "eth0",
+
+                // Shared network level flag specifying whether the client
+                // identifier should be used for identifying clients.
+                "match-client-id": true,
+
+                // Shared network name.
+                "name": "my-secret-network",
+
+                // Shared network level specification of the next server
+                // to be sent in 'siaddr'.
+                "next-server": "192.0.2.123",
+
+                // List of shared network specific DHCP options.
+                "option-data": [],
+
+                // List of IPv4 relay addresses for which this shared
+                // network is selected.
+                "relay": {
+                    "ip-addresses": []
+                },
+
+                // Shared network level rebind timer.
+                "rebind-timer": 41,
+
+                // Shared network level renew timer.
+                "renew-timer": 31,
+
+                // Shared network level compute T1 and T2 timers.
+                "calculate-tee-times": true,
+
+                // T1 = valid lifetime * .5.
+                "t1-percent": .5,
+
+                // T2 = valid lifetime * .75.
+                "t2-percent": .75,
+
+                // Cache threshold = valid lifetime * .25.
+                "cache-threshold": .25,
+
+                // Cache maximum: when the client last transmission time
+                // is close enough the lease is not renewed and current
+                // lease is returned as it was "cached".
+                "cache-max-age": 1000,
+
+                // Enumeration specifying server's mode of operation when it
+                // fetches host reservations.
+                // "reservation-mode": "all",
+                // It is replaced by the "reservations-global",
+                // "reservations-in-subnet" and "reservations-out-of-pool"
+                // parameters.
+
+                // Specify if server should lookup global reservations.
+                "reservations-global": false,
+
+                // Specify if server should lookup in-subnet reservations.
+                "reservations-in-subnet": true,
+
+                // Specify if server can assume that all reserved addresses
+                // are out-of-pool.
+                // Ignored when reservations-in-subnet is false.
+                // If specified, it is inherited by "subnet4" levels.
+                "reservations-out-of-pool": false,
+
+                // List of client classes which must be evaluated when this shared
+                // network is selected for client assignments.
+                "require-client-classes": [ "late" ],
+
+                // Turn off storage of extended information (e.g. relay agent
+                // information) with each lease for this shared-network.
+                "store-extended-info": false,
+
+                // Shared network level server hostname set in 'sname' field.
+                "server-hostname": "",
+
+                // List of IPv4 subnets belonging to this shared network.
+                "subnet4": [
+                    {
+                        // Interface name matched against inbound interface name.
+                        // Used in DHCPv4o6. See RFC 7341.
+                        "4o6-interface": "",
+
+                        // Interface ID option value. See RFC 7341.
+                        "4o6-interface-id": "",
+
+                        // Prefix matched against source address. See RFC7341.
+                        "4o6-subnet": "2001:db8:1:1::/64",
+
+                        // Subnet level authoritative flag.
+                        "authoritative": false,
+
+                        // Subnet level bootfile name, set in 'file' field.
+                        "boot-file-name": "",
+
+                        // Restricts this subnet to allow only clients that belong
+                        // to the particular client class. If an empty string is
+                        // provided, no restriction is applied.
+                        "client-class": "",
+
+                        // Subnet level value. See description at the global level.
+                        "ddns-generated-prefix": "myhost",
+
+                        // Subnet level value. See description at the global level.
+                        "ddns-override-client-update": false,
+
+                        // Subnet level value. See description at the global level.
+                        "ddns-override-no-update": false,
+
+                        // Subnet level value. See description at the global level.
+                        "ddns-qualifying-suffix": "",
+
+                        // Subnet level value. See description at the global level.
+                        "ddns-replace-client-name": "never",
+
+                        // Subnet level value. See description at the global level.
+                        "ddns-send-updates": true,
+
+                        // Subnet level value. See description at the global level.
+                        "ddns-update-on-renew": true,
+
+                        // Subnet level value. See description at the global level.
+                        "ddns-use-conflict-resolution": true,
+
+                        // Subnet level value. See description at the global level.
+                        "hostname-char-replacement": "x",
+
+                        // Subnet level value. See description at the global level.
+                        "hostname-char-set": "[^A-Za-z0-9.-]",
+
+                        // Subnet unique identifier.
+                        "id": 1,
+
+                        // Specifies that this subnet is selected for the requests
+                        // received on the particular interface.
+                        "interface": "eth0",
+
+                        // Subnet level flag specifying whether the client identifier
+                        // should be used for identifying clients.
+                        "match-client-id": true,
+
+                        // Subnet level specification of the next server to be sent
+                        // in 'siaddr'.
+                        "next-server": "0.0.0.0",
+
+                        // Turn on storage of extended information (e.g. relay agent
+                        // information) with each lease for this subnet.
+                        "store-extended-info": true,
+
+                        // Subnet level list of DHCP options.
+                        "option-data": [
+                            {
+                                // Boolean flag indicating if the particular option
+                                // should be always sent or sent only when requested.
+                                "always-send": false,
+
+                                // Option code.
+                                "code": 3,
+
+                                // Boolean flag indicating if the option value specified
+                                // in "data" is a string of hexadecimal values or human
+                                // readable CSV value.
+                                "csv-format": true,
+
+                                // Option data to be included in the option payload.
+                                "data": "192.0.3.1",
+
+                                // Option name.
+                                "name": "routers",
+
+                                // Option space. The default value "dhcp4" designates the
+                                // top level option space.
+                                "space": "dhcp4"
+                            }
+                        ],
+
+                        // List of IP address pools belonging to the subnet.
+                        "pools": [
+                            {
+                                // Restricts this pool to be only used for the client
+                                // requests belonging to a particular client class.
+                                "client-class": "phones_server1",
+
+                                // Pool level list of DHCP options.
+                                "option-data": [],
+
+                                // Address range used for client assignments.
+                                "pool": "192.1.0.1 - 192.1.0.200",
+
+                                // List of client classes which must be evaluated when this pool
+                                // is selected for client assignments.
+                                "require-client-classes": [ "late" ]
+                            },
+                            {
+                                // Restricts this pool to be only used for the client
+                                // requests belonging to a particular client class.
+                                "client-class": "phones_server2",
+
+                                // Pool level list of DHCP options.
+                                "option-data": [],
+
+                                // Address range used for client assignments.
+                                "pool": "192.3.0.1 - 192.3.0.200",
+
+                                // List of client classes which must be evaluated when this pool
+                                // is selected for client assignments.
+                                "require-client-classes": []
+                            }
+                        ],
+
+                        // Subnet level value of the rebind timer.
+                        "rebind-timer": 40,
+
+                        // List of IPv4 relay addresses for which this subnet is
+                        // selected.
+                        "relay": {
+                            "ip-addresses": [
+                                "192.168.56.1"
+                            ]
+                        },
+
+                        // Subnet level value of the renew timer.
+                        "renew-timer": 30,
+
+                        // Enumeration specifying server's mode of operation when it
+                        // fetches host reservations.
+                        // "reservation-mode": "all",
+                        // It is replaced by the "reservations-global",
+                        // "reservations-in-subnet" and
+                        // "reservations-out-of-pool" parameters.
+
+                        // Specify if server should lookup global reservations.
+                        "reservations-global": false,
+
+                        // Specify if server should lookup in-subnet reservations.
+                        "reservations-in-subnet": true,
+
+                        // Specify if server can assume that all reserved
+                        // addresses are out-of-pool.
+                        // Ignored when reservations-in-subnet is false.
+                        "reservations-out-of-pool": false,
+
+                        // Subnet level compute T1 and T2 timers.
+                        "calculate-tee-times": true,
+
+                        // T1 = valid lifetime * .5.
+                        "t1-percent": .5,
+
+                        // T2 = valid lifetime * .75.
+                        "t2-percent": .75,
+
+                        // Cache threshold = valid lifetime * .25.
+                        "cache-threshold": .25,
+
+                        // Subnet-level cache maximum.
+                        "cache-max-age": 1000,
+
+                        // List of static IPv4 reservations assigned to the clients belonging
+                        // to this subnet. For detailed example see reservations.json.
+                        "reservations": [
+                            {
+                                // Identifier used for client matching. Supported values are
+                                // "hw-address", "client-id", "duid", "circuit-id", "flex-id".
+                                "circuit-id": "01:11:22:33:44:55:66",
+
+                                // Reserved IP address.
+                                "ip-address": "192.0.2.204",
+
+                                // Hostname.
+                                "hostname": "foo.example.org",
+
+                                // Reservation specific option data.
+                                "option-data": [
+                                    {
+                                        // Option name.
+                                        "name": "vivso-suboptions",
+
+                                        // Option data.
+                                        "data": "4491"
+                                    }
+                                ]
+                            }
+                        ],
+
+                        // List of client classes which must be evaluated when this subnet
+                        // is selected for client assignments.
+                        "require-client-classes": [ "late" ],
+
+                        // Subnet level server hostname set in 'sname' field.
+                        "server-hostname": "",
+
+                        // Subnet prefix.
+                        "subnet": "192.0.0.0/8",
+
+                        // Subnet level (default) valid lifetime.
+                        "valid-lifetime": 6000,
+
+                        // Subnet level min valid lifetime.
+                        "min-valid-lifetime": 4000,
+
+                        // Subnet level max valid lifetime.
+                        "max-valid-lifetime": 8000
+                    }
+                ],
+
+                // Shared network level (default) valid lifetime.
+                "valid-lifetime": 6001,
+
+                // Subnet level min valid lifetime.
+                "min-valid-lifetime": 4001,
+
+                // Subnet level max valid lifetime.
+                "max-valid-lifetime": 8001
+            }
+        ],
+
+        // Global server hostname set in the 'sname' field.
+        "server-hostname": "",
+
+        // List of IPv4 subnets which don't belong to any shared network.
+        "subnet4": [],
+
+        // Global valid (default) lifetime value.
+        "valid-lifetime": 6000,
+
+        // Global min valid lifetime value.
+        "min-valid-lifetime": 4000,
+
+        // Global max valid lifetime value.
+        "max-valid-lifetime": 8000,
+
+        // Reservations (examples are in other files).
+        "reservations": [],
+
+        // Configuration control (currently not used, i.e. this syntax
+        // is already defined but corresponding feature is not implemented).
+        "config-control": {
+            // Only configuration databases entry is defined.
+            "config-databases": [
+                {
+                    // Name of the database to connect to.
+                    "name": "config",
+
+                    // Type of the database, e.g. "mysql", "postgresql".
+                    "type": "mysql"
+                }
+            ],
+            // Intervals between attempts to fetch configuration updates
+            // via the configuration backends used.
+            "config-fetch-wait-time": 30
+        },
+
+        // Server tag.
+        "server-tag": "my DHCPv4 server",
+
+        // DHCP queue control parameters.
+        "dhcp-queue-control": {
+            // Enable queue is mandatory.
+            "enable-queue": true,
+
+            // Queue type was mandatory.
+            "queue-type": "kea-ring4",
+
+            // Capacity is optional.
+            "capacity": 64
+        },
+
+        // Fetches host reservations.
+        // "reservation-mode": "all",
+        // It is replaced by the "reservations-global",
+        // "reservations-in-subnet" and "reservations-out-of-pool" parameters.
+
+        // Specify if server should lookup global reservations.
+        "reservations-global": false,
+
+        // Specify if server should lookup in-subnet reservations.
+        "reservations-in-subnet": true,
+
+        // Specify if server can assume that all reserved addresses
+        // are out-of-pool.
+        // Ignored when reservations-in-subnet is false.
+        // If specified, it is inherited by "shared-networks" and
+        // "subnet4" levels.
+        "reservations-out-of-pool": false,
+
+        // Global compute T1 and T2 timers.
+        "calculate-tee-times": true,
+
+        // T1 = valid lifetime * .5.
+        "t1-percent": .5,
+
+        // T2 = valid lifetime * .75.
+        "t2-percent": .75,
+
+        // Cache threshold = valid lifetime * .25.
+        "cache-threshold": .25,
+
+        // Global cache maximum.
+        "cache-max-age": 1000,
+
+        // String of zero or more characters with which to replace each
+        // invalid character in the hostname or Client FQDN. The default
+        // value is an empty string which will cause invalid characters
+        // to be omitted rather than replaced.
+        "hostname-char-replacement": "x",
+
+        // Regular expression describing the invalid character set in
+        // the hostname or Client FQDN.
+        "hostname-char-set": "[^A-Za-z0-9.-]",
+
+        // List of loggers used by the servers using this configuration file.
+        "loggers": [
+            {
+                // Debug level, a value between 0..99. The greater the value
+                // the more detailed debug log.
+                "debuglevel": 99,
+
+                // Name of the logger.
+                "name": "kea-dhcp4",
+
+                // Configures how the log should be output.
+                "output_options": [
+                    {
+                        // Determines whether the log should flushed to a file.
+                        "flush": true,
+
+                        // Specifies maximum filesize before the file is being rotated.
+                        "maxsize": 10240000,
+
+                        // Specifies the maximum number of rotated files being kept.
+                        "maxver": 1,
+
+                        // Specifies logging destination.
+                        "output": "stdout",
+
+                        // Specifies log entry content
+                        "pattern": "%D{%Y-%m-%d %H:%M:%S.%q} %-5p [%c/%i] %m\n"
+                    }
+                ],
+
+                // Specifies logging severity, i.e. "ERROR", "WARN", "INFO", "DEBUG".
+                "severity": "INFO"
+            }
+        ],
+
+        // Look at advanced example for the use of user-contexts.
+        "user-context": { }
+    }
+}
diff --git a/doc/examples/kea4/all-keys.json b/doc/examples/kea4/all-keys.json
new file mode 100644
index 0000000..3b3b722
--- /dev/null
+++ b/doc/examples/kea4/all-keys.json
@@ -0,0 +1,1155 @@
+// WARNING: This example configuration is not meant for production use.
+// The Kea DHCPv4 server will refuse this configuration because it contains
+// mutually exclusive configuration parameters.
+//
+// The primary purpose of the example file is to provide a comprehensive
+// list of parameters supported by Kea DHCPv4 server along with the brief
+// description of each parameter.
+//
+// This current version should be up to date, i.e. new keywords should be
+// added in this file at the same time than in the syntax.
+{
+    // Kea DHCPv4 server configuration begins here.
+    "Dhcp4": {
+
+        // Global authoritative flag to handle requests by clients for
+        // unknown IP addresses (ignore if disabled, NAK if enabled).
+        "authoritative": false,
+
+        // Global bootfile name to be set in the 'file' field.
+        "boot-file-name": "/dev/null",
+
+        // Ordered list of client classes used by the DHCPv4 server.
+        "client-classes": [
+            {
+                // Class specific bootfile name to be set in the 'file' field.
+                "boot-file-name": "/tmp/bootfile.efi",
+
+                // Class name.
+                "name": "phones_server1",
+
+                // Class specific next server address to use in bootstrap, which
+                // is set in 'siaddr' field.
+                "next-server": "10.2.3.4",
+
+                // Class specific DHCPv4 options list.
+                "option-data": [],
+
+                // Class specific DHCPv4 option definitions, i.e. custom formats
+                // specified for non-standard options.
+                "option-def": [],
+
+                // Class specific optional server hostname, which is set in
+                // 'sname' field.
+                "server-hostname": "",
+
+                // Class selection expression. The DHCP packet is assigned to this
+                // class when the given expression evaluates to true.
+                "test": "member('HA_server1')",
+
+                // Class valid lifetime.
+                "valid-lifetime": 6000,
+
+                // Class min valid lifetime.
+                "min-valid-lifetime": 4000,
+
+                // Class max valid lifetime.
+                "max-valid-lifetime": 8000
+            },
+            {
+                // Default value of the class specific bootfile name. Empty name
+                // means that the bootfile name is unspecified.
+                "boot-file-name": "",
+
+                // Second class name.
+                "name": "phones_server2",
+
+                // Default value of the class specific next server address. The
+                // zero IPv4 address means that it is unspecified.
+                "next-server": "0.0.0.0",
+
+                // Class specific DHCPv4 options list.
+                "option-data": [],
+
+                // Class specific DHCPv4 option definitions, i.e. custom formats
+                // specified for non-standard options.
+                "option-def": [],
+
+                // Class specific optional server hostname, which is set in
+                // 'sname' field.
+                "server-hostname": "",
+
+                // Class selection expression. The DHCP packet is assigned to this
+                // class when the given expression evaluates to true.
+                "test": "member('HA_server2')"
+            },
+
+            {
+                // Third class name.
+                "name": "late",
+
+                // Boolean flag indicating that the class expression is only evaluated
+                // when the class is required, e.g. selected address pool configuration
+                // includes this class name in its "require-client-classes" list. The
+                // default value false means that the class test expression must
+                // always be evaluated.
+                "only-if-required": true,
+
+                // Class selection expression.
+                "test": "member('ALL')"
+            }
+        ],
+
+        // Parameters for triggering behaviors compatible with broken or
+        // non-compliant clients, relays or other agents
+        "compatibility": {
+            // Parse options more leniently where fields can be deduced
+            // deterministically even if against RFC or common practice.
+            "lenient-option-parsing": true
+        },
+
+        // Command control socket configuration parameters for Kea DHCPv4 server.
+        "control-socket": {
+            // Location of the unix domain socket file the DHCPv4 server uses
+            // to receive control commands from the Kea Control Agent or the
+            // local server administrator.
+            "socket-name": "/tmp/kea4-ctrl-socket",
+
+            // Control socket type used by the Kea DHCPv4 server. The 'unix'
+            // socket is currently the only supported type.
+            "socket-type": "unix"
+        },
+
+        // Specifies a prefix to be prepended to the generated Client FQDN.
+        // It may be specified at the global, shared-network and subnet levels.
+        "ddns-generated-prefix": "myhost",
+
+        // Boolean flag indicating that server should ignore DHCP client
+        // wishes to update DNS on its own. With that flag set to true
+        // the server will send DNS updates for both forward and
+        // reverse DNS data. The default value is false, which indicates
+        // that the server will delegate DNS update to the client when
+        // requested. It may be specified at the global, shared-network
+        // and subnet levels.
+        "ddns-override-client-update": false,
+
+        // Boolean flag indicating that the server should override DHCP
+        // client's wish to not update the DNS. With this parameter
+        // set to true the server will send DNS update even when
+        // the client requested no update.  It may be specified at the
+        // global, shared-network and subnet levels.
+        "ddns-override-no-update": false,
+
+        // Suffix appended to the partial name sent to the DNS. The
+        // default value is an empty string which indicates that no
+        // suffix is appended.  It may be specified at the global,
+        // shared-network and subnet levels.
+        "ddns-qualifying-suffix": "",
+
+        // Enumeration specifying whether the server should honor
+        // hostname or Client FQDN sent by the client or replace
+        // this name. The acceptable values are: "never" (use the
+        // name the client sent), "always" (replace the name the
+        // client sent), "when-present" (replace the name the client
+        // sent, but do not generate one when the client didn't sent
+        // the name), "when-not-present" (generate the name when
+        // client didn't send one, otherwise leave the name the
+        // client sent). The default value is "never".  It may be
+        // specified at the global, shared-network and subnet levels.
+        "ddns-replace-client-name": "never",
+
+        // Boolean flag which enables or disables the DDNS updating. It
+        // defaults to true.  It may be specified at the global, shared-
+        // network and subnet levels. It works in conjunction with
+        // dhcp-ddns:enable-updates which must be true to enable connectivity
+        // to kea-dhcp-ddns.
+        "ddns-send-updates": true,
+
+        // Boolean flag, which when true instructs the server to always
+        // update DNS when leases are renewed, even if the DNS information
+        // has not changed.  The server's default behavior (i.e. flag is false)
+        // is to only update DNS if the DNS information has changed.  It
+        // may be specified at the global, shared-network and subnet levels.
+        "ddns-update-on-renew": true,
+
+        // Boolean flag, which is passed to kea-dhcp-ddns with each DDNS
+        // update request to indicate whether or not DNS update conflict
+        // resolution as described in RFC 4703 should be employed for the
+        // given update request.  The default value for this flag is true.
+        // It may be specified at the global, shared-network and subnet levels.
+        "ddns-use-conflict-resolution": true,
+
+        // Time in seconds specifying how long a declined lease should be
+        // excluded from DHCP assignments. The default value is 24 hours.
+        "decline-probation-period": 86400,
+
+        // Name Change Requests forwarding configuration for Kea DHCPv4 server.
+        // NCRs are sent to Kea D2 module to update DNS upon allocation of the
+        // DHCP leases.
+        "dhcp-ddns": {
+            // Boolean flag indicating if Kea DHCPv4 server should connect to
+            // kea-dhcp-ddns.  This must be true for NCRs to be created and
+            // sent to kea-dhcp-ddns. By default NCRs are not generated.
+            "enable-updates": false,
+
+            // Specifies maximum number of NCRs to queue waiting to be sent
+            // to Kea D2 server.
+            "max-queue-size": 1024,
+
+            // Packet format to use when sending NCRs to Kea D2 server.
+            // Currently, only JSON format is supported.
+            "ncr-format": "JSON",
+
+            // Socket protocol to use when sending NCRs to D2. Currently,
+            // only UDP is supported.
+            "ncr-protocol": "UDP",
+
+            // IP address that Kea DHCPv4 server should use to send
+            // NCRs to D2. Default value of zero indicates that Kea
+            // should pick suitable address.
+            "sender-ip": "0.0.0.0",
+
+            // Port number that Kea DHCPv4 server should use to send
+            // NCRs to D2. Default value of zero indicates that Kea
+            // should pick suitable port.
+            "sender-port": 0,
+
+            // IP address on which D2 listens for NCRs.
+            "server-ip": "127.0.0.1",
+
+            // Port number on which D2 listens for NCRs.
+            "server-port": 53001,
+
+            // The follow parameters are DEPRECATED.  They have been
+            // replaced with parameters that may be set at the global,
+            // shared-network, and subnet4 scopes.  They are listed here
+            // as configuration parsing still accepts them.  Eventually
+            // support for them will be removed.
+            "generated-prefix": "myhost",
+            "hostname-char-replacement": "x",
+            "hostname-char-set": "[^A-Za-z0-9.-]",
+            "override-client-update": false,
+            "override-no-update": false,
+            "qualifying-suffix": "",
+            "replace-client-name": "never"
+        },
+
+        // Specifies the first of the two consecutive ports of the UDP
+        // sockets used for communication between DHCPv6 and DHCPv4
+        // servers. See RFC 7341.
+        "dhcp4o6-port": 6767,
+
+        // Boolean flag indicating whether or not the Kea DHCPv4 server
+        // should send back Client Identifier option in its responses.
+        // The default value is true which indicates that the option
+        // must be sent back if the client included it. The false
+        // value instructs the server to not send this option for
+        // backward compatibility with older DHCP specifications which
+        // stated that Client Identifier must not be sent back.
+        "echo-client-id": true,
+
+        // Collection of Kea DHCPv4 server parameters configuring how
+        // the server should process expired DHCP leases.
+        "expired-leases-processing": {
+            // Specifies the number of seconds since last removal of
+            // the expired leases when next removal should occur.
+            "flush-reclaimed-timer-wait-time": 25,
+
+            // Specifies the time period in seconds to keep expired
+            // leases in the lease database (lease affinity).
+            "hold-reclaimed-time": 3600,
+
+            // Specifies the maximum number of expired leases that can be
+            // processed in a single attempt to clean up the lease
+            // database from the expired leases. If there are more
+            // expired leases, they will be processed during the next
+            // cleanup attempt.
+            "max-reclaim-leases": 100,
+
+            // Specifies the maximum time in milliseconds that the single
+            // attempt to cleanup the lease database from the expired
+            // leases may take.
+            "max-reclaim-time": 250,
+
+            // Specifies the time period in seconds since last attempt
+            // to process expired leases to initiate the next attempt.
+            "reclaim-timer-wait-time": 10,
+
+            // Specifies the maximum number of expired leases processing
+            // cycles which didn't result in full cleanup of the lease
+            // database from the expired leases, after which a
+            // warning message is issued.
+            "unwarned-reclaim-cycles": 5
+        },
+
+        // List of hooks libraries and their specific configuration parameters
+        // to be loaded by Kea DHCPv4 server.
+        "hooks-libraries": [
+            {
+                // Location of the hooks library to be loaded.
+                "library": "/opt/lib/kea/hooks/libdhcp_lease_cmds.so",
+
+                // Hook library specific configuration parameters.
+                "parameters": { }
+            }
+        ],
+
+        // List of access credentials to external sources of IPv4 reservations,
+        "hosts-databases": [
+            {
+                // Name of the database to connect to.
+                "name": "keatest",
+
+                // Host on which the database resides.
+                "host": "localhost",
+
+                // Database password.
+                "password": "keatest",
+
+                // Port on which the database is available.
+                "port": 3306,
+
+                // Type of the database, e.g. "mysql", "postgresql".
+                "type": "mysql",
+
+                // User name to be used to access the database.
+                "user": "keatest",
+
+                // Read only mode.
+                "readonly": false,
+
+                // Next entries are for the OpenSSL support in MySQL.
+
+                // Trust anchor aka certificate authority file or directory.
+                "trust-anchor": "my-ca",
+
+                // Client certificate file name.
+                "cert-file": "my-cert",
+
+                // Private key file name.
+                "key-file": "my-key",
+
+                // Cipher list (see the OpenSSL ciphers command manual).
+                "cipher-list": "AES"
+            },
+            {
+                // Name of the database to connect to.
+                "name": "keatest",
+
+                // Host on which the database resides.
+                "host": "localhost",
+
+                // Database password.
+                "password": "keatest",
+
+                // Port on which the database is available.
+                "port": 5432,
+
+                // Type of the database, e.g. "mysql", "postgresql".
+                "type": "postgresql",
+
+                // User name to be used to access the database.
+                "user": "keatest"
+            },
+            {
+                // Name of the database to connect to.
+                "name": "keatest",
+
+                // Database password.
+                "password": "keatest",
+
+                // Port on which the database is available.
+                "port": 9042,
+
+                // Type of the database, e.g. "mysql", "postgresql".
+                "type": "mysql",
+
+                // User name to be used to access the database.
+                "user": "keatest",
+
+                // Connection reconnect wait time.
+                // This parameter governs how long Kea waits before attempting
+                // to reconnect. Expressed in milliseconds. The default is 0
+                // (disabled) for MySQL and PostgreSQL.
+                "reconnect-wait-time": 3000,
+
+                // Connection maximum reconnect tries.
+                "max-reconnect-tries": 3,
+
+                // Action to take when connection recovery fails.
+                // Supported values: stop-retry-exit, serve-retry-exit,
+                // serve-retry-continue
+                "on-fail": "stop-retry-exit",
+
+                // Connection connect timeout.
+                "connect-timeout": 100
+            }
+        ],
+
+        // List of host reservation identifier types to be used by the
+        // Kea DHCPv4 server to fetch static reservations for the
+        // DHCP clients. All identifiers are used by default, which
+        // means that the server will issue multiple queries to the
+        // database to find if there is a reservation for the particular
+        // client. If the particular deployment uses only subset, e.g.
+        // one, identifier type, this identifier should be only listed
+        // here to prevent unnecessary queries to the database.
+        "host-reservation-identifiers": [
+            "hw-address",
+            "duid",
+            "circuit-id",
+            "client-id",
+            "flex-id"
+        ],
+
+        // Specifies configuration of interfaces on which the Kea DHCPv4
+        // server is listening to the DHCP queries.
+        "interfaces-config": {
+            // Specifies whether the server should use "udp" socket or
+            // "raw" sockets to listen to the DHCP traffic. The "raw"
+            // sockets are useful when direct DHCP traffic is being
+            // received.
+            "dhcp-socket-type": "udp",
+
+            // Specifies a list of interfaces on which the Kea DHCPv4
+            // server should listen to the DHCP requests.
+            "interfaces": [
+                "eth0"
+            ],
+
+            // Enumeration which indicates what interface should be used
+            // to send DHCP response to the client. The default value is
+            // "same-as-inbound" which indicates that the response should
+            // be sent via the interface on which the client's query
+            // was received. The "use-routing" value indicates that the
+            // Kea server should use kernel's routing table to find the
+            // suitable interface.
+            "outbound-interface": "same-as-inbound",
+
+            // Boolean flag indicating if the available interfaces should
+            // be re-detected upon server reconfiguration. The default value
+            // is true which means that the interfaces are always
+            // re-detected.
+            "re-detect": true,
+
+            // Kea tries to bind the service sockets during initialization. It may
+            // fail due to a port being already opened or misconfiguration. Kea can
+            // suppress these errors and only logs them. This flag prevents starting
+            // the DHCP server without binding all sockets. If unspecified, it
+            // defaults to false.
+            "service-sockets-require-all": true,
+
+            // Kea tries to bind the service sockets during initialization. This
+            // option specifies how many times binding to interface will be retried.
+            // The default value is 0 which means that the operation will not be
+            // repeated.
+            "service-sockets-max-retries": 5,
+
+            // The time interval in milliseconds to wait before the next attempt to
+            // retry opening a service socket.
+            "service-sockets-retry-wait-time": 5000
+        },
+
+        // Boolean parameter which controls whether an early global host
+        // reservations lookup should be performed. This lookup takes place
+        // before subnet selection and when a global reservation is found
+        // with some client classes, it triggers a second phase classification.
+        // It can also be used to drop queries using host reservations as a
+        // decision table indexed by reservation identifiers.
+        "early-global-reservations-lookup": true,
+
+        // Boolean parameter which controls DHCP server's behavior with respect
+        // to creating host reservations for the same IP address. By default
+        // this flag is set to true in which case the server prevents creation
+        // of multiple host reservations for the same IP address. When this
+        // parameter is set to false, the server allows for creating multiple
+        // reservations for the same IP address within a subnet. This setting
+        // is useful in deployments in which a given host may be communicating
+        // with a DHCP server over multiple interfaces and depending on the
+        // chosen interface different MAC address (or other identifier) will
+        // be used to identify the host. Note that some host backends do not
+        // support the mode in which multiple reservations for the same IP
+        // address are used. If these backends are in use and this setting
+        // is attempted a configuration error will occur. The MySQL and
+        // PostgreSQL backends do support this mode.
+        "ip-reservations-unique": true,
+
+        /// Boolean parameter which controls whether host reservations lookup
+        /// should be performed before lease lookup. This parameter has effect
+        /// only when multi-threading is disabled. When multi-threading is
+        /// enabled, host reservations lookup is always performed first to avoid
+        /// lease lookup resource locking.
+        "reservations-lookup-first": true,
+
+        // Specifies credentials to access lease database.
+        "lease-database": {
+            // memfile backend specific parameter specifying the interval
+            // in seconds at which lease file should be cleaned up (outdated
+            // lease entries are removed to prevent lease file from growing
+            // infinitely).
+            "lfc-interval": 3600,
+
+            // Maximum number of lease file read errors allowed before
+            // loading the file is abandoned.  Defaults to 0 (no limit).
+            "max-row-errors": 100,
+
+            // Name of the lease file. In case of database it specifies the
+            // database name.
+            "name": "/tmp/kea-dhcp4.csv",
+
+            // memfile specific parameter indicating whether leases should
+            // be saved on persistent storage (disk) or not. The true value
+            // is the default and it indicates that leases are stored in the
+            // persistent storage. This setting must be used in production.
+            // The false value should only be used for testing purposes
+            // because non stored leases will be lost upon Kea server restart.
+            "persist": true,
+
+            // Lease database backend type, i.e. "memfile", "mysql" or
+            // "postgresql".
+            "type": "memfile"
+        },
+
+        // Boolean value indicating if the Kea DHCPv4 server should use client
+        // identifier value sent by the client or ignore it. The default value
+        // is true which indicate that the server should use client identifier
+        // and that it takes precedence over client's MAC address. In deployments
+        // where MAC address should take precedence this value can be set to
+        // false, in which case the clients will be identified by MAC address.
+        // This is specifically useful when clients don't generate unique
+        // identifiers or these identifiers are not stable etc.
+        "match-client-id": false,
+
+        // Global value of the next server address set in 'siaddr' field.
+        // The global value may be overridden in lower level configuration
+        // scopes.
+        "next-server": "192.0.2.123",
+
+        // Global value which limits the number of client packets (e.g.
+        // DHCPREQUESTs) that may be parked while waiting for hook library
+        // work to complete, prior to a response (e.g. DHCPACK) being sent
+        // back to the client.  A typical example is when kea-dhcp4 parks a
+        // DHCPREQUEST while it sends the lease update(s) to its HA peer(s).
+        // The packet is unparked once the update(s) have been acknowledged.
+        // This value limits the number of packets that can be held pending
+        // the updates. In times of heavy client traffic, this value can keep
+        // kea-dhcp4 from building an insurmountable backlog of updates.
+        "parked-packet-limit": 128,
+
+        // List of global DHCP options that Kea DHCPv4 server assigns to the
+        // clients.
+        "option-data": [
+            {
+                // Boolean flag indicating if the given option is always
+                // send in response or only when requested. The default
+                // value of false indicates that it is only sent when
+                // requested.
+                "always-send": false,
+
+                // Option code. It is not required if the option name is
+                // provided.
+                "code": 6,
+
+                // Boolean value indicating whether the option data specified
+                // in the "data" field is specified as a string of hexadecimal
+                // digits or in human readable CSV format.
+                "csv-format": true,
+
+                // Option data to be stored in the option payload.
+                "data": "192.0.3.1, 192.0.3.2",
+
+                // Option name. It is not required of the option code is
+                // provided.
+                "name": "domain-name-servers",
+
+                // Option space. The default is the "dhcp4" option space which
+                // groups top level DHCPv4 options.
+                "space": "dhcp4"
+            }
+        ],
+
+        // List of global option definitions, i.e. option formats, that the
+        // Kea DHCPv4 server is using.
+        "option-def": [
+            {
+                // Boolean flag indicating if the option definition comprises
+                // an array of values of some type, e.g. array of IPv4 addresses.
+                // The default value of false means that the option does not
+                // comprise an array of values.
+                "array": false,
+
+                // Option code.
+                "code": 6,
+
+                // Holds a name of the option space encapsulated by this option.
+                // All options that belong to this option space will be sent
+                // as sub-options of this option. Empty string means that this
+                // option doesn't encapsulate any option.
+                "encapsulate": "",
+
+                // Option name.
+                "name": "my-option",
+
+                // Specifies the types of fields within the option if the option
+                // is said to be a "record" (see "type"). in this particular example
+                // this option comprises two fields, 1 byte and 2 bytes long.
+                "record-types": "uint8, uint16",
+
+                // Name of the option space to which this option belongs.
+                "space": "my-space",
+
+                // Option type. All possible types are listed in the Kea
+                // Administrator Reference Manual.
+                "type": "record"
+            }
+        ],
+
+        // Global value for the rebind timer, i.e. the time after which the
+        // DHCP client enters rebind state if it fails to renew the lease.
+        "rebind-timer": 40,
+
+        // Global value for the renew timer, i.e. the timer after which the
+        // DHCP client renews the lease.
+        "renew-timer": 30,
+
+        // Global value to store extended information (e.g. relay agent
+        // information) with each lease.
+        "store-extended-info": true,
+
+        // Statistics keep some samples per observation point.
+        // There are two default values: maximum count and maximum age.
+        // Set the maximum count to zero disables it.
+        "statistic-default-sample-count": 0,
+
+        // When the maximum count is 0 the maximum age (in seconds) applies.
+        "statistic-default-sample-age": 60,
+
+        // Multi-threading parameters.
+        "multi-threading": {
+            // By default Kea processes packets on a single thread (default
+            // 'false' value for this option). To enable multi-threading, this
+            // option can be set ('true' value).
+            "enable-multi-threading": false,
+
+            // When multi-threading is enabled, Kea will process packets on a
+            // number of multiple threads configurable through this option. The
+            // value must be a positive integer (0 means auto detect).
+            "thread-pool-size": 0,
+
+            // When multi-threading is enabled, Kea will read packets from the
+            // interface and append a working item to the thread pool. This
+            // option configures the maximum number of items that can be queued.
+            // The value must be a positive integer (0 means unlimited).
+            "packet-queue-size": 0
+        },
+
+        // Governs how the Kea DHCPv4 server should deal with the invalid
+        // data received from the client.
+        "sanity-checks": {
+            // Specifies how the Kea DHCPv4 server should behave when invalid
+            // data is read for a lease from the lease file. The following
+            // values are supported "none" (don't attempt to correct the
+            // lease information), "warn" (print a warning for subnet-id
+            // related inconsistencies), "fix" (correct the subnet id by
+            // trying to find the suitable subnet), "fix-del" (similar
+            // to "fix" but delete the lease if no suitable subnet found),
+            // "del" (delete the lease if the lease has invalid subnet
+            // identifier value).
+            "lease-checks": "warn"
+        },
+
+        // List of shared networks used by Kea DHCPv4 server. The shared
+        // networks group subnets together.
+        "shared-networks": [
+            {
+                // Shared network level authoritative flag.
+                "authoritative": false,
+
+                // Shared network level bootfile name.
+                "boot-file-name": "/dev/null",
+
+                // Restricts this shared network to allow only clients
+                // that belong to the particular client class. If an
+                // empty string is provided, no restriction is applied.
+                "client-class": "",
+
+                // Shared network level value. See description at the global level.
+                "ddns-generated-prefix": "myhost",
+
+                // Shared network level value. See description at the global level.
+                "ddns-override-client-update": false,
+
+                // Shared network level value. See description at the global level.
+                "ddns-override-no-update": false,
+
+                // Shared network level value. See description at the global level.
+                "ddns-qualifying-suffix": "",
+
+                // Shared network level value. See description at the global level.
+                "ddns-replace-client-name": "never",
+
+                // Shared network level value. See description at the global level.
+                "ddns-send-updates": true,
+
+                // Shared network level value. See description at the global level.
+                "ddns-update-on-renew": true,
+
+                // Shared network level value. See description at the global level.
+                "ddns-use-conflict-resolution": true,
+
+                // Shared network level value. See description at the global level.
+                "hostname-char-replacement": "x",
+
+                // Shared network level value. See description at the global level.
+                "hostname-char-set": "[^A-Za-z0-9.-]",
+
+                // Specifies that this shared network is selected for the
+                // requests received on the particular interface.
+                "interface": "eth0",
+
+                // Shared network level flag specifying whether the client
+                // identifier should be used for identifying clients.
+                "match-client-id": true,
+
+                // Shared network name.
+                "name": "my-secret-network",
+
+                // Shared network level specification of the next server
+                // to be sent in 'siaddr'.
+                "next-server": "192.0.2.123",
+
+                // List of shared network specific DHCP options.
+                "option-data": [],
+
+                // List of IPv4 relay addresses for which this shared
+                // network is selected.
+                "relay": {
+                    "ip-addresses": []
+                },
+
+                // Shared network level rebind timer.
+                "rebind-timer": 41,
+
+                // Shared network level renew timer.
+                "renew-timer": 31,
+
+                // Shared network level compute T1 and T2 timers.
+                "calculate-tee-times": true,
+
+                // T1 = valid lifetime * .5.
+                "t1-percent": .5,
+
+                // T2 = valid lifetime * .75.
+                "t2-percent": .75,
+
+                // Cache threshold = valid lifetime * .25.
+                "cache-threshold": .25,
+
+                // Cache maximum: when the client last transmission time
+                // is close enough the lease is not renewed and current
+                // lease is returned as it was "cached".
+                "cache-max-age": 1000,
+
+                // Enumeration specifying server's mode of operation when it
+                // fetches host reservations.
+                // "reservation-mode": "all",
+                // It is replaced by the "reservations-global",
+                // "reservations-in-subnet" and "reservations-out-of-pool"
+                // parameters.
+
+                // Specify if server should lookup global reservations.
+                "reservations-global": false,
+
+                // Specify if server should lookup in-subnet reservations.
+                "reservations-in-subnet": true,
+
+                // Specify if server can assume that all reserved addresses
+                // are out-of-pool.
+                // Ignored when reservations-in-subnet is false.
+                // If specified, it is inherited by "subnet4" levels.
+                "reservations-out-of-pool": false,
+
+                // List of client classes which must be evaluated when this shared
+                // network is selected for client assignments.
+                "require-client-classes": [ "late" ],
+
+                // Turn off storage of extended information (e.g. relay agent
+                // information) with each lease for this shared-network.
+                "store-extended-info": false,
+
+                // Shared network level server hostname set in 'sname' field.
+                "server-hostname": "",
+
+                // List of IPv4 subnets belonging to this shared network.
+                "subnet4": [
+                    {
+                        // Interface name matched against inbound interface name.
+                        // Used in DHCPv4o6. See RFC 7341.
+                        "4o6-interface": "",
+
+                        // Interface ID option value. See RFC 7341.
+                        "4o6-interface-id": "",
+
+                        // Prefix matched against source address. See RFC7341.
+                        "4o6-subnet": "2001:db8:1:1::/64",
+
+                        // Subnet level authoritative flag.
+                        "authoritative": false,
+
+                        // Subnet level bootfile name, set in 'file' field.
+                        "boot-file-name": "",
+
+                        // Restricts this subnet to allow only clients that belong
+                        // to the particular client class. If an empty string is
+                        // provided, no restriction is applied.
+                        "client-class": "",
+
+                        // Subnet level value. See description at the global level.
+                        "ddns-generated-prefix": "myhost",
+
+                        // Subnet level value. See description at the global level.
+                        "ddns-override-client-update": false,
+
+                        // Subnet level value. See description at the global level.
+                        "ddns-override-no-update": false,
+
+                        // Subnet level value. See description at the global level.
+                        "ddns-qualifying-suffix": "",
+
+                        // Subnet level value. See description at the global level.
+                        "ddns-replace-client-name": "never",
+
+                        // Subnet level value. See description at the global level.
+                        "ddns-send-updates": true,
+
+                        // Subnet level value. See description at the global level.
+                        "ddns-update-on-renew": true,
+
+                        // Subnet level value. See description at the global level.
+                        "ddns-use-conflict-resolution": true,
+
+                        // Subnet level value. See description at the global level.
+                        "hostname-char-replacement": "x",
+
+                        // Subnet level value. See description at the global level.
+                        "hostname-char-set": "[^A-Za-z0-9.-]",
+
+                        // Subnet unique identifier.
+                        "id": 1,
+
+                        // Specifies that this subnet is selected for the requests
+                        // received on the particular interface.
+                        "interface": "eth0",
+
+                        // Subnet level flag specifying whether the client identifier
+                        // should be used for identifying clients.
+                        "match-client-id": true,
+
+                        // Subnet level specification of the next server to be sent
+                        // in 'siaddr'.
+                        "next-server": "0.0.0.0",
+
+                        // Turn on storage of extended information (e.g. relay agent
+                        // information) with each lease for this subnet.
+                        "store-extended-info": true,
+
+                        // Subnet level list of DHCP options.
+                        "option-data": [
+                            {
+                                // Boolean flag indicating if the particular option
+                                // should be always sent or sent only when requested.
+                                "always-send": false,
+
+                                // Option code.
+                                "code": 3,
+
+                                // Boolean flag indicating if the option value specified
+                                // in "data" is a string of hexadecimal values or human
+                                // readable CSV value.
+                                "csv-format": true,
+
+                                // Option data to be included in the option payload.
+                                "data": "192.0.3.1",
+
+                                // Option name.
+                                "name": "routers",
+
+                                // Option space. The default value "dhcp4" designates the
+                                // top level option space.
+                                "space": "dhcp4"
+                            }
+                        ],
+
+                        // List of IP address pools belonging to the subnet.
+                        "pools": [
+                            {
+                                // Restricts this pool to be only used for the client
+                                // requests belonging to a particular client class.
+                                "client-class": "phones_server1",
+
+                                // Pool level list of DHCP options.
+                                "option-data": [],
+
+                                // Address range used for client assignments.
+                                "pool": "192.1.0.1 - 192.1.0.200",
+
+                                // List of client classes which must be evaluated when this pool
+                                // is selected for client assignments.
+                                "require-client-classes": [ "late" ]
+                            },
+                            {
+                                // Restricts this pool to be only used for the client
+                                // requests belonging to a particular client class.
+                                "client-class": "phones_server2",
+
+                                // Pool level list of DHCP options.
+                                "option-data": [],
+
+                                // Address range used for client assignments.
+                                "pool": "192.3.0.1 - 192.3.0.200",
+
+                                // List of client classes which must be evaluated when this pool
+                                // is selected for client assignments.
+                                "require-client-classes": []
+                            }
+                        ],
+
+                        // Subnet level value of the rebind timer.
+                        "rebind-timer": 40,
+
+                        // List of IPv4 relay addresses for which this subnet is
+                        // selected.
+                        "relay": {
+                            "ip-addresses": [
+                                "192.168.56.1"
+                            ]
+                        },
+
+                        // Subnet level value of the renew timer.
+                        "renew-timer": 30,
+
+                        // Enumeration specifying server's mode of operation when it
+                        // fetches host reservations.
+                        // "reservation-mode": "all",
+                        // It is replaced by the "reservations-global",
+                        // "reservations-in-subnet" and
+                        // "reservations-out-of-pool" parameters.
+
+                        // Specify if server should lookup global reservations.
+                        "reservations-global": false,
+
+                        // Specify if server should lookup in-subnet reservations.
+                        "reservations-in-subnet": true,
+
+                        // Specify if server can assume that all reserved
+                        // addresses are out-of-pool.
+                        // Ignored when reservations-in-subnet is false.
+                        "reservations-out-of-pool": false,
+
+                        // Subnet level compute T1 and T2 timers.
+                        "calculate-tee-times": true,
+
+                        // T1 = valid lifetime * .5.
+                        "t1-percent": .5,
+
+                        // T2 = valid lifetime * .75.
+                        "t2-percent": .75,
+
+                        // Cache threshold = valid lifetime * .25.
+                        "cache-threshold": .25,
+
+                        // Subnet-level cache maximum.
+                        "cache-max-age": 1000,
+
+                        // List of static IPv4 reservations assigned to the clients belonging
+                        // to this subnet. For detailed example see reservations.json.
+                        "reservations": [
+                            {
+                                // Identifier used for client matching. Supported values are
+                                // "hw-address", "client-id", "duid", "circuit-id", "flex-id".
+                                "circuit-id": "01:11:22:33:44:55:66",
+
+                                // Reserved IP address.
+                                "ip-address": "192.0.2.204",
+
+                                // Hostname.
+                                "hostname": "foo.example.org",
+
+                                // Reservation specific option data.
+                                "option-data": [
+                                    {
+                                        // Option name.
+                                        "name": "vivso-suboptions",
+
+                                        // Option data.
+                                        "data": "4491"
+                                    }
+                                ]
+                            }
+                        ],
+
+                        // List of client classes which must be evaluated when this subnet
+                        // is selected for client assignments.
+                        "require-client-classes": [ "late" ],
+
+                        // Subnet level server hostname set in 'sname' field.
+                        "server-hostname": "",
+
+                        // Subnet prefix.
+                        "subnet": "192.0.0.0/8",
+
+                        // Subnet level (default) valid lifetime.
+                        "valid-lifetime": 6000,
+
+                        // Subnet level min valid lifetime.
+                        "min-valid-lifetime": 4000,
+
+                        // Subnet level max valid lifetime.
+                        "max-valid-lifetime": 8000
+                    }
+                ],
+
+                // Shared network level (default) valid lifetime.
+                "valid-lifetime": 6001,
+
+                // Subnet level min valid lifetime.
+                "min-valid-lifetime": 4001,
+
+                // Subnet level max valid lifetime.
+                "max-valid-lifetime": 8001
+            }
+        ],
+
+        // Global server hostname set in the 'sname' field.
+        "server-hostname": "",
+
+        // List of IPv4 subnets which don't belong to any shared network.
+        "subnet4": [],
+
+        // Global valid (default) lifetime value.
+        "valid-lifetime": 6000,
+
+        // Global min valid lifetime value.
+        "min-valid-lifetime": 4000,
+
+        // Global max valid lifetime value.
+        "max-valid-lifetime": 8000,
+
+        // Reservations (examples are in other files).
+        "reservations": [],
+
+        // Configuration control (currently not used, i.e. this syntax
+        // is already defined but corresponding feature is not implemented).
+        "config-control": {
+            // Only configuration databases entry is defined.
+            "config-databases": [
+                {
+                    // Name of the database to connect to.
+                    "name": "config",
+
+                    // Type of the database, e.g. "mysql", "postgresql".
+                    "type": "mysql"
+                }
+            ],
+            // Intervals between attempts to fetch configuration updates
+            // via the configuration backends used.
+            "config-fetch-wait-time": 30
+        },
+
+        // Server tag.
+        "server-tag": "my DHCPv4 server",
+
+        // DHCP queue control parameters.
+        "dhcp-queue-control": {
+            // Enable queue is mandatory.
+            "enable-queue": true,
+
+            // Queue type was mandatory.
+            "queue-type": "kea-ring4",
+
+            // Capacity is optional.
+            "capacity": 64
+        },
+
+        // Fetches host reservations.
+        // "reservation-mode": "all",
+        // It is replaced by the "reservations-global",
+        // "reservations-in-subnet" and "reservations-out-of-pool" parameters.
+
+        // Specify if server should lookup global reservations.
+        "reservations-global": false,
+
+        // Specify if server should lookup in-subnet reservations.
+        "reservations-in-subnet": true,
+
+        // Specify if server can assume that all reserved addresses
+        // are out-of-pool.
+        // Ignored when reservations-in-subnet is false.
+        // If specified, it is inherited by "shared-networks" and
+        // "subnet4" levels.
+        "reservations-out-of-pool": false,
+
+        // Global compute T1 and T2 timers.
+        "calculate-tee-times": true,
+
+        // T1 = valid lifetime * .5.
+        "t1-percent": .5,
+
+        // T2 = valid lifetime * .75.
+        "t2-percent": .75,
+
+        // Cache threshold = valid lifetime * .25.
+        "cache-threshold": .25,
+
+        // Global cache maximum.
+        "cache-max-age": 1000,
+
+        // String of zero or more characters with which to replace each
+        // invalid character in the hostname or Client FQDN. The default
+        // value is an empty string which will cause invalid characters
+        // to be omitted rather than replaced.
+        "hostname-char-replacement": "x",
+
+        // Regular expression describing the invalid character set in
+        // the hostname or Client FQDN.
+        "hostname-char-set": "[^A-Za-z0-9.-]",
+
+        // List of loggers used by the servers using this configuration file.
+        "loggers": [
+            {
+                // Debug level, a value between 0..99. The greater the value
+                // the more detailed debug log.
+                "debuglevel": 99,
+
+                // Name of the logger.
+                "name": "kea-dhcp4",
+
+                // Configures how the log should be output.
+                "output_options": [
+                    {
+                        // Determines whether the log should flushed to a file.
+                        "flush": true,
+
+                        // Specifies maximum filesize before the file is being rotated.
+                        "maxsize": 10240000,
+
+                        // Specifies the maximum number of rotated files being kept.
+                        "maxver": 1,
+
+                        // Specifies logging destination.
+                        "output": "stdout",
+
+                        // Specifies log entry content
+                        "pattern": "%D{%Y-%m-%d %H:%M:%S.%q} %-5p [%c/%i] %m\n"
+                    }
+                ],
+
+                // Specifies logging severity, i.e. "ERROR", "WARN", "INFO", "DEBUG".
+                "severity": "INFO"
+            }
+        ],
+
+        // Look at advanced example for the use of user-contexts.
+        "user-context": { }
+    }
+}
diff --git a/doc/examples/kea4/all-options.json b/doc/examples/kea4/all-options.json
new file mode 100644
index 0000000..49dbbf9
--- /dev/null
+++ b/doc/examples/kea4/all-options.json
@@ -0,0 +1,1720 @@
+// This example configuration file for DHCPv4 server in Kea contains:
+//
+// - data for all the standard options
+// - custom option definitions at global level along with some associated
+// option data
+// - custom option data with standardized option spaces other than "dhcp4"
+// - custom option spaces
+// - option embedding examples
+//
+// The reader is strongly encouraged to take a look at the option formats
+// documented in the Kea ARM:
+// https://kea.readthedocs.io/en/latest/arm/dhcp4-srv.html?highlight=list%20of%20standard%20dhcpv4#id2
+
+{
+  "Dhcp4": {
+    /*                Data for all standard option definitions                */
+    // Option data defined globally
+    "option-data": [
+      /*
+       Code   Len        Time Offset
+      +-----+-----+-----+-----+-----+-----+
+      |  2  |  4  |  n1 |  n2 |  n3 |  n4 |
+      +-----+-----+-----+-----+-----+-----+
+      */
+      // Type: int32
+      {
+        "code": 2,
+        "data": "-25200",
+        "name": "time-offset"
+      },
+
+      /*
+       Code   Len         Address 1               Address 2
+      +-----+-----+-----+-----+-----+-----+-----+-----+--
+      |  3  |  n  |  a1 |  a2 |  a3 |  a4 |  a1 |  a2 |  ...
+      +-----+-----+-----+-----+-----+-----+-----+-----+--
+      */
+      // Type: array of {IPv4 address}
+      {
+        "code": 3,
+        "data": "192.0.2.2, 192.0.2.3",
+        "name": "routers"
+      },
+
+      /*
+       Code   Len         Address 1               Address 2
+      +-----+-----+-----+-----+-----+-----+-----+-----+--
+      |  4  |  n  |  a1 |  a2 |  a3 |  a4 |  a1 |  a2 |  ...
+      +-----+-----+-----+-----+-----+-----+-----+-----+--
+      */
+      // Type: array of {IPv4 address}
+      {
+        "code": 4,
+        "data": "192.0.2.4, 192.0.2.5",
+        "name": "time-servers"
+      },
+
+      /*
+       Code   Len         Address 1               Address 2
+      +-----+-----+-----+-----+-----+-----+-----+-----+--
+      |  5  |  n  |  a1 |  a2 |  a3 |  a4 |  a1 |  a2 |  ...
+      +-----+-----+-----+-----+-----+-----+-----+-----+--
+      */
+      // Type: array of {IPv4 address}
+      {
+        "code": 5,
+        "data": "192.0.2.6, 192.0.2.7",
+        "name": "name-servers"
+      },
+
+      /*
+       Code   Len         Address 1               Address 2
+      +-----+-----+-----+-----+-----+-----+-----+-----+--
+      |  6  |  n  |  a1 |  a2 |  a3 |  a4 |  a1 |  a2 |  ...
+      +-----+-----+-----+-----+-----+-----+-----+-----+--
+      */
+      // Type: array of {IPv4 address}
+      {
+        "code": 6,
+        "data": "192.0.2.8, 192.0.2.9",
+        "name": "domain-name-servers"
+      },
+
+      /*
+       Code   Len         Address 1               Address 2
+      +-----+-----+-----+-----+-----+-----+-----+-----+--
+      |  7  |  n  |  a1 |  a2 |  a3 |  a4 |  a1 |  a2 |  ...
+      +-----+-----+-----+-----+-----+-----+-----+-----+--
+      */
+      // Type: array of {IPv4 address}
+      {
+        "code": 7,
+        "data": "192.0.2.10, 192.0.2.11",
+        "name": "log-servers"
+      },
+
+      /*
+       Code   Len         Address 1               Address 2
+      +-----+-----+-----+-----+-----+-----+-----+-----+--
+      |  8  |  n  |  a1 |  a2 |  a3 |  a4 |  a1 |  a2 |  ...
+      +-----+-----+-----+-----+-----+-----+-----+-----+--
+      */
+      // Type: array of {IPv4 address}
+      {
+        "code": 8,
+        "data": "192.0.2.12, 192.0.2.13",
+        "name": "cookie-servers"
+      },
+
+      /*
+       Code   Len         Address 1               Address 2
+      +-----+-----+-----+-----+-----+-----+-----+-----+--
+      |  9  |  n  |  a1 |  a2 |  a3 |  a4 |  a1 |  a2 |  ...
+      +-----+-----+-----+-----+-----+-----+-----+-----+--
+      */
+      // Type: array of {IPv4 address}
+      {
+        "code": 9,
+        "data": "192.0.2.14, 192.0.2.15",
+        "name": "lpr-servers"
+      },
+
+      /*
+       Code   Len         Address 1               Address 2
+      +-----+-----+-----+-----+-----+-----+-----+-----+--
+      |  10 |  n  |  a1 |  a2 |  a3 |  a4 |  a1 |  a2 |  ...
+      +-----+-----+-----+-----+-----+-----+-----+-----+--
+      */
+      // Type: array of {IPv4 address}
+      {
+        "code": 10,
+        "data": "192.0.2.16, 192.0.2.17",
+        "name": "impress-servers"
+      },
+
+      /*
+       Code   Len         Address 1               Address 2
+      +-----+-----+-----+-----+-----+-----+-----+-----+--
+      |  11 |  n  |  a1 |  a2 |  a3 |  a4 |  a1 |  a2 |  ...
+      +-----+-----+-----+-----+-----+-----+-----+-----+--
+      */
+      // Type: array of {IPv4 address}
+      {
+        "code": 11,
+        "data": "192.0.2.18, 192.0.2.19",
+        "name": "resource-location-servers"
+      },
+
+      /*
+       Code   Len   File Size
+      +-----+-----+-----+-----+
+      |  13 |  2  |  l1 |  l2 |
+      +-----+-----+-----+-----+
+      */
+      // Type: uint16
+      {
+        "code": 13,
+        "data": "1024",
+        "name": "boot-size"
+      },
+
+      /*
+       Code   Len      Dump File Pathname
+      +-----+-----+-----+-----+-----+-----+---
+      |  14 |  n  |  n1 |  n2 |  n3 |  n4 | ...
+      +-----+-----+-----+-----+-----+-----+---
+      */
+      // Type: string
+      {
+        "code": 14,
+        "data": "/etc/crash-dump.img",
+        "name": "merit-dump"
+      },
+
+      /*
+       Code   Len        Domain Name
+      +-----+-----+-----+-----+-----+-----+--
+      |  15 |  n  |  d1 |  d2 |  d3 |  d4 |  ...
+      +-----+-----+-----+-----+-----+-----+--
+      */
+      // Type: FQDN
+      {
+        "code": 15,
+        "data": "my.example.org",
+        "name": "domain-name"
+      },
+
+      /*
+       Code   Len    Swap Server Address
+      +-----+-----+-----+-----+-----+-----+
+      |  16 |  n  |  a1 |  a2 |  a3 |  a4 |
+      +-----+-----+-----+-----+-----+-----+
+      */
+      // Type: IPv4 address
+      {
+        "code": 16,
+        "data": "192.0.2.20",
+        "name": "swap-server"
+      },
+
+      /*
+       Code   Len      Root Disk Pathname
+      +-----+-----+-----+-----+-----+-----+---
+      |  17 |  n  |  n1 |  n2 |  n3 |  n4 | ...
+      +-----+-----+-----+-----+-----+-----+---
+      */
+      // Type: string
+      {
+        "code": 17,
+        "data": "/path/to/root",
+        "name": "root-path"
+      },
+
+      /*
+       Code   Len      Extensions Pathname
+      +-----+-----+-----+-----+-----+-----+---
+      |  18 |  n  |  n1 |  n2 |  n3 |  n4 | ...
+      +-----+-----+-----+-----+-----+-----+---
+      */
+      // Type: string
+      {
+        "code": 18,
+        "data": "/path/to/extensions",
+        "name": "extensions-path"
+      },
+
+      /*
+       Code   Len  Value
+      +-----+-----+-----+
+      |  19 |  1  | 0/1 |
+      +-----+-----+-----+
+      */
+      // Type: boolean
+      {
+        "code": 19,
+        "data": "true",
+        "name": "ip-forwarding"
+      },
+
+      /*
+       Code   Len  Value
+      +-----+-----+-----+
+      |  20 |  1  | 0/1 |
+      +-----+-----+-----+
+      */
+      // Type: boolean
+      {
+        "code": 20,
+        "data": "true",
+        "name": "non-local-source-routing"
+      },
+
+      /*
+       Code   Len         Address 1                  Mask 1
+      +-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+
+      |  21 |  n  |  a1 |  a2 |  a3 |  a4 |  m1 |  m2 |  m3 |  m4 |
+      +-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+
+              Address 2                  Mask 2
+      +-----+-----+-----+-----+-----+-----+-----+-----+---
+      |  a1 |  a2 |  a3 |  a4 |  m1 |  m2 |  m3 |  m4 | ...
+      +-----+-----+-----+-----+-----+-----+-----+-----+---
+      */
+      // Type: array of {IPv4 address}
+      {
+        "code": 21,
+        "data": "192.0.2.21, 192.0.2.22",
+        "name": "policy-filter"
+      },
+
+      /*
+       Code   Len      Size
+      +-----+-----+-----+-----+
+      |  22 |  2  |  s1 |  s2 |
+      +-----+-----+-----+-----+
+      */
+      // Type: uint16
+      {
+        "code": 22,
+        "data": "2048",
+        "name": "max-dgram-reassembly"
+      },
+
+      /*
+       Code   Len   TTL
+      +-----+-----+-----+
+      |  23 |  1  | ttl |
+      +-----+-----+-----+
+      */
+      // Type: uint8
+      {
+        "code": 23,
+        "data": "248",
+        "name": "default-ip-ttl"
+      },
+
+      /*
+       Code   Len           Timeout
+      +-----+-----+-----+-----+-----+-----+
+      |  24 |  4  |  t1 |  t2 |  t3 |  t4 |
+      +-----+-----+-----+-----+-----+-----+
+      */
+      // Type: uint32
+      {
+        "code": 24,
+        "data": "131072",
+        "name": "path-mtu-aging-timeout"
+      },
+
+      /*
+       Code   Len     Size 1      Size 2
+      +-----+-----+-----+-----+-----+-----+---
+      |  25 |  n  |  s1 |  s2 |  s1 |  s2 | ...
+      +-----+-----+-----+-----+-----+-----+---
+      */
+      // Type: array of {uint16}
+      {
+        "code": 25,
+        "data": "3072, 4096",
+        "name": "path-mtu-plateau-table"
+      },
+
+      /*
+       Code   Len      MTU
+      +-----+-----+-----+-----+
+      |  26 |  2  |  m1 |  m2 |
+      +-----+-----+-----+-----+
+      */
+      // Type: uint16
+      {
+        "code": 26,
+        "data": "5120",
+        "name": "interface-mtu"
+      },
+
+      /*
+       Code   Len  Value
+      +-----+-----+-----+
+      |  27 |  1  | 0/1 |
+      +-----+-----+-----+
+      */
+      // Type: boolean
+      {
+        "code": 27,
+        "data": "true",
+        "name": "all-subnets-local"
+      },
+
+      /*
+       Code   Len     Broadcast Address
+      +-----+-----+-----+-----+-----+-----+
+      |  28 |  4  |  b1 |  b2 |  b3 |  b4 |
+      +-----+-----+-----+-----+-----+-----+
+      */
+      // Type: IPv4 address
+      {
+        "code": 28,
+        "data": "192.0.2.255",
+        "name": "broadcast-address"
+      },
+
+      /*
+       Code   Len  Value
+      +-----+-----+-----+
+      |  29 |  1  | 0/1 |
+      +-----+-----+-----+
+      */
+      // Type: boolean
+      {
+        "code": 29,
+        "data": "true",
+        "name": "perform-mask-discovery"
+      },
+
+      /*
+       Code   Len  Value
+      +-----+-----+-----+
+      |  30 |  1  | 0/1 |
+      +-----+-----+-----+
+      */
+      // Type: boolean
+      {
+        "code": 30,
+        "data": "true",
+        "name": "mask-supplier"
+      },
+
+      /*
+       Code   Len  Value
+      +-----+-----+-----+
+      |  31 |  1  | 0/1 |
+      +-----+-----+-----+
+      */
+      // Type: boolean
+      {
+        "code": 31,
+        "data": "true",
+        "name": "router-discovery"
+      },
+
+      /*
+       Code   Len            Address
+      +-----+-----+-----+-----+-----+-----+
+      |  32 |  4  |  a1 |  a2 |  a3 |  a4 |
+      +-----+-----+-----+-----+-----+-----+
+      */
+      // Type: IPv4 address
+      {
+        "code": 32,
+        "data": "192.0.2.23",
+        "name": "router-solicitation-address"
+      },
+
+      /*
+       Code   Len         Destination 1           Router 1
+      +-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+
+      |  33 |  n  |  d1 |  d2 |  d3 |  d4 |  r1 |  r2 |  r3 |  r4 |
+      +-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+
+              Destination 2           Router 2
+      +-----+-----+-----+-----+-----+-----+-----+-----+---
+      |  d1 |  d2 |  d3 |  d4 |  r1 |  r2 |  r3 |  r4 | ...
+      +-----+-----+-----+-----+-----+-----+-----+-----+---
+      */
+      // Type: array of {IPv4 address}
+      {
+        "code": 33,
+        "data": "192.0.2.24, 192.0.2.25",
+        "name": "static-routes"
+      },
+
+      /*
+       Code   Len  Value
+      +-----+-----+-----+
+      |  34 |  1  | 0/1 |
+      +-----+-----+-----+
+      */
+      // Type: boolean
+      {
+        "code": 34,
+        "data": "true",
+        "name": "trailer-encapsulation"
+      },
+
+      /*
+       Code   Len           Time
+      +-----+-----+-----+-----+-----+-----+
+      |  35 |  4  |  t1 |  t2 |  t3 |  t4 |
+      +-----+-----+-----+-----+-----+-----+
+      */
+      // Type: uint32
+      {
+        "code": 35,
+        "data": "196608",
+        "name": "arp-cache-timeout"
+      },
+
+      /*
+       Code   Len  Value
+      +-----+-----+-----+
+      |  36 |  1  | 0/1 |
+      +-----+-----+-----+
+      */
+      // Type: boolean
+      {
+        "code": 36,
+        "data": "true",
+        "name": "ieee802-3-encapsulation"
+      },
+
+      /*
+       Code   Len   TTL
+      +-----+-----+-----+
+      |  37 |  1  |  n  |
+      +-----+-----+-----+
+      */
+      // Type: uint8
+      {
+        "code": 37,
+        "data": "124",
+        "name": "default-tcp-ttl"
+      },
+
+      /*
+       Code   Len           Time
+      +-----+-----+-----+-----+-----+-----+
+      |  38 |  4  |  t1 |  t2 |  t3 |  t4 |
+      +-----+-----+-----+-----+-----+-----+
+      */
+      // Type: uint32
+      {
+        "code": 38,
+        "data": "262144",
+        "name": "tcp-keepalive-interval"
+      },
+
+      /*
+       Code   Len  Value
+      +-----+-----+-----+
+      |  39 |  1  | 0/1 |
+      +-----+-----+-----+
+      */
+      // Type: boolean
+      {
+        "code": 39,
+        "data": "true",
+        "name": "tcp-keepalive-garbage"
+      },
+
+      /*
+       Code   Len      NIS Domain Name
+      +-----+-----+-----+-----+-----+-----+---
+      |  40 |  n  |  n1 |  n2 |  n3 |  n4 | ...
+      +-----+-----+-----+-----+-----+-----+---
+      */
+      // Type: string
+      {
+        "code": 40,
+        "data": "nis.example.org",
+        "name": "nis-domain"
+      },
+
+      /*
+       Code   Len         Address 1               Address 2
+      +-----+-----+-----+-----+-----+-----+-----+-----+--
+      |  41 |  n  |  a1 |  a2 |  a3 |  a4 |  a1 |  a2 |  ...
+      +-----+-----+-----+-----+-----+-----+-----+-----+--
+      */
+      // Type: array of {IPv4 address}
+      {
+        "code": 41,
+        "data": "192.0.2.26, 192.0.2.27",
+        "name": "nis-servers"
+      },
+
+      /*
+       Code   Len         Address 1               Address 2
+      +-----+-----+-----+-----+-----+-----+-----+-----+--
+      |  42 |  n  |  a1 |  a2 |  a3 |  a4 |  a1 |  a2 |  ...
+      +-----+-----+-----+-----+-----+-----+-----+-----+--
+      */
+      // Type: array of {IPv4 address}
+      {
+        "code": 42,
+        "data": "192.0.2.28, 192.0.2.29",
+        "name": "ntp-servers"
+      },
+
+      /*
+       Code   Len   Vendor-specific information
+      +-----+-----+-----+-----+---
+      |  43 |  n  |  i1 |  i2 | ...
+      +-----+-----+-----+-----+---
+
+       Code   Len   Data item        Code   Len   Data item       Code
+      +-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+
+      |  T1 |  n  |  d1 |  d2 | ... |  T2 |  n  |  D1 |  D2 | ... | ... |
+      +-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+
+      */
+      // Type: empty
+      {
+        "code": 43,
+        "name": "vendor-encapsulated-options"
+      },
+
+      /*
+       Code   Len           Address 1              Address 2
+      +-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+----
+      |  44 |  n  |  a1 |  a2 |  a3 |  a4 |  b1 |  b2 |  b3 |  b4 | ...
+      +-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+----
+      */
+      // Type: array of {IPv4 address}
+      {
+        "code": 44,
+        "data": "192.0.2.30, 192.0.2.31",
+        "name": "netbios-name-servers"
+      },
+
+      /*
+       Code   Len           Address 1              Address 2
+      +-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+----
+      |  45 |  n  |  a1 |  a2 |  a3 |  a4 |  b1 |  b2 |  b3 |  b4 | ...
+      +-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+----
+      */
+      // Type: array of {IPv4 address}
+      {
+        "code": 45,
+        "data": "192.0.2.32, 192.0.2.33",
+        "name": "netbios-dd-server"
+      },
+
+      /*
+      Value         Node Type
+      -----         ---------
+      0x1           B-node
+      0x2           P-node
+      0x4           M-node
+      0x8           H-node
+
+       Code   Len  Node Type
+      +-----+-----+-----------+
+      |  46 |  1  | see above |
+      +-----+-----+-----------+
+      */
+      // Type: uint8
+      {
+        "code": 46,
+        "data": "0x1",
+        "name": "netbios-node-type"
+      },
+
+      /*
+       Code   Len       NetBIOS Scope
+      +-----+-----+-----+-----+-----+-----+----
+      |  47 |  n  |  s1 |  s2 |  s3 |  s4 | ...
+      +-----+-----+-----+-----+-----+-----+----
+      */
+      // Type: string
+      {
+        "code": 47,
+        "data": "scope42",
+        "name": "netbios-scope"
+      },
+
+      /*
+       Code   Len         Address 1               Address 2
+      +-----+-----+-----+-----+-----+-----+-----+-----+---
+      |  48 |  n  |  a1 |  a2 |  a3 |  a4 |  a1 |  a2 |   ...
+      +-----+-----+-----+-----+-----+-----+-----+-----+---
+      */
+      // Type: array of {IPv4 address}
+      {
+        "code": 48,
+        "data": "192.0.2.34, 192.0.2.35",
+        "name": "font-servers"
+      },
+
+      /*
+       Code   Len         Address 1               Address 2
+      +-----+-----+-----+-----+-----+-----+-----+-----+---
+      |  49 |  n  |  a1 |  a2 |  a3 |  a4 |  a1 |  a2 |   ...
+      +-----+-----+-----+-----+-----+-----+-----+-----+---
+      */
+      // Type: array of {IPv4 address}
+      {
+        "code": 49,
+        "data": "192.0.2.36, 192.0.2.37",
+        "name": "x-display-manager"
+      },
+
+      /*
+      Value   Meaning
+      -----   --------
+        1     the 'file' field is used to hold options
+        2     the 'sname' field is used to hold options
+        3     both fields are used to hold options
+
+       Code   Len  Value
+      +-----+-----+-----+
+      |  52 |  1  |1/2/3|
+      +-----+-----+-----+
+      */
+      // Type: uint8
+      {
+        "code": 52,
+        "data": "3",
+        "name": "dhcp-option-overload"
+      },
+
+      /*
+       Code   Len            Address
+      +-----+-----+-----+-----+-----+-----+
+      |  54 |  4  |  a1 |  a2 |  a3 |  a4 |
+      +-----+-----+-----+-----+-----+-----+
+      */
+      // Type: IPv4 address
+      {
+        "code": 54,
+        "data": "192.0.2.39",
+        "name": "dhcp-server-identifier"
+      },
+
+      /*
+       Code   Len     Text
+      +-----+-----+-----+-----+---
+      |  56 |  n  |  c1 |  c2 | ...
+      +-----+-----+-----+-----+---
+      */
+      // Type: string
+      {
+        "code": 56,
+        "data": "Error: here's a DHCPNAK!",
+        "name": "dhcp-message"
+      },
+
+      /*
+       Code   Len     Length
+      +-----+-----+-----+-----+
+      |  57 |  2  |  l1 |  l2 |
+      +-----+-----+-----+-----+
+      */
+      // Type: uint16
+      {
+        "code": 57,
+        "data": "1536",
+        "name": "dhcp-max-message-size"
+      },
+
+      /*
+       Code   Len   Vendor class Identifier
+      +-----+-----+-----+-----+---
+      |  60 |  n  |  i1 |  i2 | ...
+      +-----+-----+-----+-----+---
+      */
+      // Type: string
+      {
+        "code": 60,
+        "data": "ISC",
+        "name": "vendor-class-identifier"
+      },
+
+      /*
+       Code  Len    NetWare/IP Domain Name
+      +-----+-----+------+------+------+-----
+      |  62 |  n  |  c1  |  c2  |  c3  |  ...
+      +-----+-----+------+------+------+-----
+      */
+      // Type: string
+      {
+        "code": 62,
+        "data": "nwip.example.org",
+        "name": "nwip-domain-name"
+      },
+
+      /*
+       Code   Len  NetWare/IP General Info
+      +-----+-----+----+----+
+      | 63  | 11  | 2  |  0 |
+      +-----+-----+----+----+
+                   NWIP_EXIST_IN_OPTIONS_AREA (length 0)
+
+                  +----+----+----+
+                  |  5 |  1 |  1 |
+                  +----+----+----+
+                   NSQ_BROADCAST_SERVER (length 1)
+                   value is YES
+
+                  +----+----+------------+
+                  |  7 |  4 | IP address |
+                  +----+----+------------+
+                   NEAREST_NWIP_SERVER (length 4)
+                   value is IP address of server
+      */
+      // Type: binary
+      {
+        "code": 63,
+        "data": "1A BB AD AB BA D0 00 00 00 00 00 00 00 00 CA FE",
+        "name": "nwip-suboptions"
+      },
+
+      /*
+       Code   Len      NIS Client Domain Name
+      +-----+-----+-----+-----+-----+-----+---
+      |  64 |  n  |  n1 |  n2 |  n3 |  n4 | ...
+      +-----+-----+-----+-----+-----+-----+---
+      */
+      // Type: string
+      {
+        "code": 64,
+        "data": "nisplus.example.org",
+        "name": "nisplus-domain-name"
+      },
+
+      /*
+       Code   Len         Address 1               Address 2
+      +-----+-----+-----+-----+-----+-----+-----+-----+--
+      |  65 |  n  |  a1 |  a2 |  a3 |  a4 |  a1 |  a2 |  ...
+      +-----+-----+-----+-----+-----+-----+-----+-----+--
+      */
+      // Type: IPv4 address
+      {
+        "code": 65,
+        "data": "192.0.2.40",
+        "name": "nisplus-servers"
+      },
+
+      /*
+       Code  Len   TFTP server
+      +-----+-----+-----+-----+-----+---
+      | 66  |  n  |  c1 |  c2 |  c3 | ...
+      +-----+-----+-----+-----+-----+---
+      */
+      // Type: string
+      {
+        "code": 66,
+        "data": "tftp.example.org",
+        "name": "tftp-server-name"
+      },
+
+      /*
+       Code  Len   Bootfile name
+      +-----+-----+-----+-----+-----+---
+      | 67  |  n  |  c1 |  c2 |  c3 | ...
+      +-----+-----+-----+-----+-----+---
+      */
+      // Type: string
+      {
+        "code": 67,
+        "data": "boot-file.img",
+        "name": "boot-file-name"
+      },
+
+      /*
+       Code Len    Home Agent Addresses (zero or more)
+      +-----+-----+-----+-----+-----+-----+--
+      | 68  |  n  | a1  | a2  | a3  | a4  | ...
+      +-----+-----+-----+-----+-----+-----+--
+      */
+      // Type: array of {IPv4 address}
+      {
+        "code": 68,
+        "data": "192.0.2.41, 192.0.2.42",
+        "name": "mobile-ip-home-agent"
+      },
+
+      /*
+       Code   Len         Address 1               Address 2
+      +-----+-----+-----+-----+-----+-----+-----+-----+--
+      | 69  |  n  |  a1 |  a2 |  a3 |  a4 |  a1 |  a2 |  ...
+      +-----+-----+-----+-----+-----+-----+-----+-----+--
+      */
+      // Type: array of {IPv4 address}
+      {
+        "code": 69,
+        "data": "192.0.2.43, 192.0.2.44",
+        "name": "smtp-server"
+      },
+
+      /*
+       Code   Len         Address 1               Address 2
+      +-----+-----+-----+-----+-----+-----+-----+-----+--
+      | 70  |  n  |  a1 |  a2 |  a3 |  a4 |  a1 |  a2 |  ...
+      +-----+-----+-----+-----+-----+-----+-----+-----+--
+      */
+      // Type: array of {IPv4 address}
+      {
+        "code": 70,
+        "data": "192.0.2.45, 192.0.2.46",
+        "name": "pop-server"
+      },
+
+      /*
+       Code   Len         Address 1               Address 2
+      +-----+-----+-----+-----+-----+-----+-----+-----+--
+      | 71  |  n  |  a1 |  a2 |  a3 |  a4 |  a1 |  a2 |  ...
+      +-----+-----+-----+-----+-----+-----+-----+-----+--
+      */
+      // Type: array of {IPv4 address}
+      {
+        "code": 71,
+        "data": "192.0.2.47, 192.0.2.48",
+        "name": "nntp-server"
+      },
+
+      /*
+       Code   Len         Address 1               Address 2
+      +-----+-----+-----+-----+-----+-----+-----+-----+--
+      | 72  |  n  |  a1 |  a2 |  a3 |  a4 |  a1 |  a2 |  ...
+      +-----+-----+-----+-----+-----+-----+-----+-----+--
+      */
+      // Type: array of {IPv4 address}
+      {
+        "code": 72,
+        "data": "192.0.2.49, 192.0.2.50",
+        "name": "www-server"
+      },
+
+      /*
+       Code   Len         Address 1               Address 2
+      +-----+-----+-----+-----+-----+-----+-----+-----+--
+      | 73  |  n  |  a1 |  a2 |  a3 |  a4 |  a1 |  a2 |  ...
+      +-----+-----+-----+-----+-----+-----+-----+-----+--
+      */
+      // Type: array of {IPv4 address}
+      {
+        "code": 73,
+        "data": "192.0.2.51, 192.0.2.52",
+        "name": "finger-server"
+      },
+
+      /*
+       Code   Len         Address 1               Address 2
+      +-----+-----+-----+-----+-----+-----+-----+-----+--
+      | 74  |  n  |  a1 |  a2 |  a3 |  a4 |  a1 |  a2 |  ...
+      +-----+-----+-----+-----+-----+-----+-----+-----+--
+      */
+      // Type: array of {IPv4 address}
+      {
+        "code": 74,
+        "data": "192.0.2.53, 192.0.2.54",
+        "name": "irc-server"
+      },
+
+      /*
+       Code   Len         Address 1               Address 2
+      +-----+-----+-----+-----+-----+-----+-----+-----+--
+      | 75  |  n  |  a1 |  a2 |  a3 |  a4 |  a1 |  a2 |  ...
+      +-----+-----+-----+-----+-----+-----+-----+-----+--
+      */
+      // Type: array of {IPv4 address}
+      {
+        "code": 75,
+        "data": "192.0.2.55, 192.0.2.56",
+        "name": "streettalk-server"
+      },
+
+      /*
+       Code   Len         Address 1               Address 2
+      +-----+-----+-----+-----+-----+-----+-----+-----+--
+      | 76  |  n  |  a1 |  a2 |  a3 |  a4 |  a1 |  a2 |  ...
+      +-----+-----+-----+-----+-----+-----+-----+-----+--
+      */
+      // Type: array of {IPv4 address}
+      {
+        "code": 76,
+        "data": "192.0.2.57, 192.0.2.58",
+        "name": "streettalk-directory-assistance-server"
+      },
+
+      /*
+       Code   Len   Value
+      +-----+-----+---------------------  . . .  --+
+      | 77  |  N  | User Class Data ('Len' octets) |
+      +-----+-----+---------------------  . . .  --+
+      */
+      // Type: binary
+      {
+        "code": 77,
+        "data": "1A BB AD AB BA D0 00 00 00 00 00 00 00 00 CA FE",
+        "name": "user-class"
+      },
+
+      /*
+       0                   1                   2                   3
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |   Code = 78   |    Length     |   Mandatory   |      a1       |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |      a2       |       a3      |       a4      |      ...
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      */
+      // Type: boolean, array of {IPv4 address}
+      {
+        "code": 78,
+        "data": "true, 192.0.2.59, 192.0.2.60",
+        "name": "slp-directory-agent"
+      },
+
+      /*
+       0                   1                   2                   3
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |   Code = 79   |     Length    |   Mandatory   | <Scope List>...
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      */
+      // Type: boolean, string
+      {
+        "code": 79,
+        "data": "true, slp-scope",
+        "name": "slp-service-scope"
+      },
+
+      // Option code 80 is not defined in Kea.
+      // Option code 83 is not defined in Kea.
+      // Option code 84 is unassigned.
+
+      /*
+       Code   Len        Address 1               Address 2
+      +-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+--
+      | 85  |  n  |  a1 |  a2 | a3  |  a4 |  a1 |  a2 |  a3 |  a4 |  ...
+      +-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+--
+      */
+      // Type: array of IPv4 address
+      {
+        "code": 85,
+        "data": "192.0.2.61, 192.0.2.62",
+        "name": "nds-servers"
+      },
+
+      /*
+       Code Len  NDS Tree Name
+      +----+----+----+----+----+----+--
+      | 86 | n  | c1 | c2 | c3 | c4 |  ...
+      +----+----+----+----+----+----+--
+      */
+      // Type: string
+      {
+        "code": 86,
+        "data": "my-tree",
+        "name": "nds-tree-name"
+      },
+
+      /*
+       Code Len  Initial NDS Context
+      +----+----+----+----+----+----+--
+      | 87 | n  | c1 | c2 | c3 | c4 |  ...
+      +----+----+----+----+----+----+--
+      */
+      // Type: string
+      {
+        "code": 87,
+        "data": "context",
+        "name": "nds-context"
+      },
+
+      /*
+       Code   Len  FQDN(s) of BCMCS Controller
+      +-----+-----+-----+-----+-----+-----+-----+--
+      | 88  |  n  |  s1 |  s2 |  s3 |  s4 | s5  |  ...
+      +-----+-----+-----+-----+-----+-----+-----+--
+      */
+      // Type: FQDN
+      {
+        "code": 88,
+        "data": "bcms-controller.example.org",
+        "name": "bcms-controller-names"
+      },
+
+      /*
+       Code   Len  Address 1               Address 2
+      +-----+-----+-----+-----+-----+-----+-----+--
+      | 89  |  n  | a1  | a2  | a3  | a4  | a1  |  ...
+      +-----+-----+-----+-----+-----+-----+-----+--
+      */
+      // Type: array of {IPv4 address}
+      {
+        "code": 89,
+        "data": "192.0.2.63",
+        "name": "bcms-controller-address"
+      },
+
+      /*
+       Code  Len  16-bit Type
+      +----+-----+-----+-----+
+      | 93 |  n  | n1  | n2  |
+      +----+-----+-----+-----+
+      */
+      // Type: array of uint16
+      {
+        "code": 93,
+        "data": "6144, 7168",
+        "name": "client-system"
+      },
+
+      /*
+       Code  Len  Type Major Minor
+      +----+-----+----+-----+-----+
+      | 94 |  3  |  t |  M  |  m  |
+      +----+-----+----+-----+-----+
+      */
+      // Type: uint8, uint8, uint8
+      {
+        "code": 94,
+        "data": "0, 1, 0",
+        "name": "client-ndi"
+      },
+
+      // Option code 95 is unsupported.
+      // Option code 96 is unassigned.
+
+      /*
+       Code  Len  Type  Machine Identifier
+      +----+-----+----+-----+ . . . +-----+
+      | 97 |  n  |  t |     | . . . |     |
+      +----+-----+----+-----+ . . . +-----+
+      */
+      // Type: uint8, binary
+      {
+        "code": 97,
+        "data": "0, 1A BB AD AB BA D0 00 00 00 00 00 00 00 00 CA FE",
+        "name": "uuid-guid"
+      },
+
+      /*
+      0                   1                   2                   3
+      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |     Code      |    Length     |   URL list
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+         Code            98
+
+         Length          The length of the data field (i.e., URL list) in
+                         bytes.
+
+         URL list        A list of one or more URLs separated by the ASCII
+                         space character (0x20).
+      */
+      // Type: string
+      {
+        "code": 98,
+        "data": "uap1.example.org uap2.example.org",
+        "name": "uap-servers"
+      },
+
+      /*
+      0                   1                   2                   3
+      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      | GEOCONF_CIVIC |       N       |      what     |    country    |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |    code       |        civic address elements                ...
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+      Code GEOCONF_CIVIC:  The code for this DHCP option is 99.
+
+      N:  The length of this option is variable.  The minimum length is 3
+         octets.
+
+      what:  The 'what' element describes to which location the DHCP entry
+         refers.  Currently, three options are defined: the location of the
+         DHCP server (a value of 0), the location of the network element
+         believed to be closest to the client (a value of 1), or the
+         location of the client (a value of 2).  Option (2) SHOULD be used,
+         but may not be known.  Options (0) and (1) SHOULD NOT be used
+         unless it is known that the DHCP client is in close physical
+         proximity to the server or network element.
+
+      country code:  The two-letter ISO 3166 country code in capital ASCII
+         letters, e.g., DE or US.  (Civic addresses always contain country
+         designations, suggesting the use of a fixed-format field to save
+         space.)
+
+      civic address elements:  Zero or more elements comprising the civic
+         and/or postal address, with the format described below
+         (Section 3.3).
+      */
+      // Type: binary
+      {
+        "code": 99,
+        "data": "1A BB AD AB BA D0 00 00 00 00 00 00 00 00 CA FE",
+        "name": "geoconf-civic"
+      },
+
+      /*
+       PCode  Len   TZ-POSIX String
+      +-----+-----+------------------------------+
+      | 100 |  N  | IEEE 1003.1 String           |
+      +-----+-----+------------------------------+
+      */
+      // Type: string
+      {
+        "code": 100,
+        // String options that have a comma in their values need to have
+        // it escaped (i.e. each comma is preceded by two backslashes).
+        // That's because commas are reserved for separating fields in
+        // compound options. At the same time, we need to be conformant
+        // with JSON spec, that does not allow "\,". Therefore the
+        // slightly uncommon double backslashes notation is needed.
+        // The value sent over the wire is:
+        // EST5EDT4,M3.2.0/02:00,M11.1.0/02:00
+        "data": "EST5EDT4\\,M3.2.0/02:00\\,M11.1.0/02:00",
+        "name": "pcode"
+      },
+
+      /*
+       TCode  Len   TZ-Database String
+      +-----+-----+------------------------------+
+      | 101 |  N  | Reference to the TZ Database |
+      +-----+-----+------------------------------+
+      */
+      // Type: string
+      {
+        "code": 101,
+        "data": "Europe/Zurich",
+        "name": "tcode"
+      },
+
+      // Option codes 102-107 are unassigned.
+
+      /*
+       0                   1                   2                   3
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |     Code      |   Length      |           Value               |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |         Value (cont.)         |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+      Code:  8-bit identifier of the IPv6-Only Preferred option code as
+         assigned by IANA: 108.  The client includes the Code in the
+         Parameter Request List in DHCPDISCOVER and DHCPREQUEST messages as
+         described in Section 3.2.
+
+      Length:  8-bit unsigned integer.  The length of the option, excluding
+         the Code and Length Fields.  The server MUST set the length field
+         to 4.  The client MUST ignore the IPv6-Only Preferred option if
+         the length field value is not 4.
+
+      Value:  32-bit unsigned integer.  The number of seconds for which the
+         client should disable DHCPv4 (V6ONLY_WAIT configuration variable).
+         If the server pool is explicitly configured with a V6ONLY_WAIT
+         timer, the server MUST set the field to that configured value.
+         Otherwise, the server MUST set it to zero.  The client MUST
+         process that field as described in Section 3.2.
+      */
+      // Type: uint32
+      {
+        "code": 108,
+        "data": "3600",
+        "name": "v6-only-preferred"
+      },
+
+      // Option codes 109-111 are unassigned.
+
+      // Type: array of {IPv4 address}
+      {
+        "code": 112,
+        "data": "192.0.2.63, 192.0.2.64",
+        "name": "netinfo-server-address"
+      },
+
+      // Type: string
+      {
+        "code": 113,
+        "data": "server1",
+        "name": "netinfo-server-tag"
+      },
+
+      // Type: string
+      {
+        "code": 114,
+        "data": "https://default.example.org",
+        "name": "v4-captive-portal"
+      },
+
+      // Option code 115 is unassigned.
+
+      /*
+       Code   Len   Value
+      +-----+-----+-----+
+      | 116 |  1  |  a  |
+      +-----+-----+-----+
+      */
+      // Type: uint8
+      {
+        "code": 116,
+        "data": "1",
+        "name": "auto-config"
+      },
+
+      /*
+           Code            Length      Name Service Search Order in Sequence
+       0                   1                   2                   3
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |     117       |     Len       |             ns1               |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |             ns2               |             ...               |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      */
+      // Type: array of {uint16}
+      {
+        "code": 117,
+        "data": "6, 41, 44, 65",
+        "name": "name-service-search"
+      },
+
+      /*
+       Code   Len        IPv4 Address
+      +-----+-----+-----+-----+-----+-----+
+      | 118 |  4  | A1  | A2  | A3  | A4  |
+      +-----+-----+-----+-----+-----+-----+
+      */
+      // Type: IPv4 address
+      {
+        "code": 118,
+        "data": "192.0.2.65",
+        "name": "subnet-selection"
+      },
+
+      /*
+       0                   1                   2                   3
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |     119       |     Len       |         Searchstring...
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                     Searchstring...
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      */
+      // Type: array of {FQDN}
+      {
+        "code": 119,
+        "data": "example.com, example.org",
+        "name": "domain-search"
+      },
+
+      // Option codes 120-123 are not defined in Kea.
+
+      /*
+                           1 1 1 1 1 1
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |  option-code  |  option-len   |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |      enterprise-number1       |
+      |                               |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |   data-len1   |               |
+      +-+-+-+-+-+-+-+-+               |
+      /      vendor-class-data1       /
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ----
+      |      enterprise-number2       |   ^
+      |                               |   |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+   |
+      |   data-len2   |               | optional
+      +-+-+-+-+-+-+-+-+               |   |
+      /      vendor-class-data2       /   |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+   |
+      ~            ...                ~   V
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ----
+
+      option-code         OPTION_V-I_VENDOR_CLASS (124)
+
+      option-len          total length of all following option data in
+                          octets
+
+      enterprise-numberN  The vendor's 32-bit Enterprise Number as
+                          registered with IANA [3]
+
+      data-lenN           Length of vendor-class-data field
+
+      vendor-class-dataN  Details of the hardware configuration of the
+                          host on which the client is running, or of
+                          industry consortium compliance
+      */
+      // Type: uint32, binary
+      {
+        "code": 124,
+        "data": "4491, 0f BA AD AB BA D0 00 00 00 00 00 00 00 00 CA FE",
+        "name": "vivco-suboptions"
+      },
+
+      /*
+                           1 1 1 1 1 1
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |  option-code  |  option-len   |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |      enterprise-number1       |
+      |                               |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |   data-len1   |               |
+      +-+-+-+-+-+-+-+-+ option-data1  |
+      /                               /
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ----
+      |      enterprise-number2       |   ^
+      |                               |   |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+   |
+      |   data-len2   |               | optional
+      +-+-+-+-+-+-+-+-+ option-data2  |   |
+      /                               /   |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+   |
+      ~            ...                ~   V
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ----
+
+      option-code         OPTION_V-I_VENDOR_OPTS (125)
+
+      option-len          total length of all following option data in
+                          octets
+
+      enterprise-numberN  The vendor's registered 32-bit Enterprise Number
+                          as registered with IANA [3]
+
+      data-lenN           Length of option-data field
+
+      option-dataN        Vendor-specific options, described below
+      */
+      // Type: uint32
+      {
+        "code": 125,
+        "data": "4491",
+        "name": "vivso-suboptions"
+      },
+
+    // Option codes 126-127 are unassigned.
+    // Option codes 128-135 are not defined in Kea.
+
+      /*
+      0                   1
+      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |  option-code  | option-length |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                               |
+      +      PAA IPv4 Address         +
+      |                               |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |             ...               |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+         Figure 1: PAA DHCPv4 option
+
+      option-code:        OPTION_PANA_AGENT (136).
+
+      option-length:      Length of the 'options' field in octets;
+                          MUST be a multiple of four (4).
+
+      PAA IPv4 Address:   IPv4 address of a PAA for the client to use.
+                          The PAAs are listed in the order of preference
+                          for use by the client.
+      */
+      // Type: array of {IPv4 address}
+      {
+        "code": 136,
+        "data": "192.0.2.66, 192.0.2.67",
+        "name": "pana-agent"
+      },
+
+      /*
+      Code    Len   LoST Server Domain Name
+      +-----+-----+-----+-----+-----+-----+-----+----
+      | 137 |  n  |  s1 |  s2 |  s3 |  s4 | s5  |  ...
+      +-----+-----+-----+-----+-----+-----+-----+----
+      */
+      // Type: FQDN
+      {
+        "code": 137,
+        "data": "lost.example.org",
+        "name": "v4-lost"
+      },
+
+      /*
+      0                   1
+      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |  option-code  | option-length |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                               |
+      +       AC IPv4 Address         +
+      |                               |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |             ...               |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+      option-code:   OPTION_CAPWAP_AC_V4 (138)
+
+      option-length:   Length of the 'options' field in octets; MUST be a
+         multiple of four (4).
+
+      AC IPv4 Address:  IPv4 address of a CAPWAP AC that the WTP may use.
+         The ACs are listed in the order of preference for use by the WTP
+      */
+      // Type: array of {IPv4 address}
+      {
+        "code": 138,
+        "data": "192.0.2.68, 192.0.2.69",
+        "name": "capwap-ac-v4"
+      },
+
+      // Option codes 139-140 are not defined in Kea.
+
+      /*
+       0                   1                   2                   3
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |      141      |     Len       |         Searchstring...       |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                     Searchstring...                           |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      */
+      // Type: array of {FQDN}
+      {
+        "code": 141,
+        "data": "example.com, example.org",
+        "name": "sip-ua-cs-domains"
+      },
+
+      // Option codes 142-145 are not defined in Kea.
+
+      // Type: uint8, IPv4 address, IPv4 address, array of {FQDN}
+      {
+        "code": 146,
+        "data": "1, 192.0.2.70, 192.0.2.71, example.com, example.org",
+        "name": "rdnss-selection"
+      },
+
+      // Option codes 147-158 are not defined in Kea.
+
+      // Type: uint8, PSID
+      {
+        "code": 159,
+        "data": "2, 3/4",
+        "name": "v4-portparams"
+      },
+
+      // Option codes 161-209 are unassigned.
+
+      /*
+      0                   1                   2                   3
+      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |  OPTION_6RD   | option-length |  IPv4MaskLen  |  6rdPrefixLen |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                                                               |
+      |                           6rdPrefix                           |
+      |                          (16 octets)                          |
+      |                                                               |
+      |                                                               |
+      |                                                               |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |                     6rdBRIPv4Address(es)                      |
+      .                                                               .
+      .                                                               .
+      .                                                               .
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+      option-code         OPTION_6RD (212)
+
+      option-length       The length of the DHCP option in octets (22
+                          octets with one BR IPv4 address).
+
+      IPv4MaskLen         The number of high-order bits that are identical
+                          across all CE IPv4 addresses within a given 6rd
+                          domain.  This may be any value between 0 and 32.
+                          Any value greater than 32 is invalid.
+
+      6rdPrefixLen        The IPv6 prefix length of the SP's 6rd IPv6
+                          prefix in number of bits.  For the purpose of
+                          bounds checking by DHCP option processing, the
+                          sum of (32 - IPv4MaskLen) + 6rdPrefixLen MUST be
+                          less than or equal to 128.
+
+      6rdBRIPv4Address    One or more IPv4 addresses of the 6rd Border
+                          Relay(s) for a given 6rd domain.
+
+      6rdPrefix           The service provider's 6rd IPv6 prefix
+                          represented as a 16-octet IPv6 address.  The bits
+                          in the prefix after the 6rdPrefixlen number of
+                          bits are reserved and MUST be initialized to zero
+                          by the sender and ignored by the receiver.
+      */
+      // Type: uint8, uint8, IPv6 address, array of {IPv4 address}
+      {
+        "code": 212,
+        "data": "24, 96, 2001:db8::f001, 192.0.2.72, 192.0.2.73",
+        "name": "option-6rd"
+      },
+
+      /*
+       0                   1                   2                   3
+       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |     Code      |   Length      |  Access Network Domain Name   .
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      .            Access Network Domain Name (cont.)                 .
+      .                              ...                              .
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+      option-code:  OPTION_V4_ACCESS_DOMAIN (213).
+
+      option-length:  The length of the entire access network domain name
+         option in octets.
+
+      option-value:  The domain name associated with the access network,
+         encoded as described in Section 3.1.
+      */
+      // Type: FQDN
+      {
+        "code": 213,
+        "data": "example.org",
+        "name": "v4-access-domain"
+      },
+
+      // Option codes 214-219 are unassigned.
+      // Option codes 220-221 are not defined in Kea.
+      // Option codes 222-254 are unassigned
+
+      /*                         Custom option data                           */
+      // See "option-def" below for the definitions.
+      {
+        "code": 1,
+        "name": "my-empty-option",
+        "space": "my-fancy-space"
+      },
+      {
+        "code": 224,
+        "data": "192.0.2.74, 3/4, 1, example.org, string",
+        "name": "my-lengthy-option",
+        "space": "my-fancy-space"
+      },
+      {
+        "code": 254,
+        "data": "127, 32767, 2147483647, 255, 65535, 4294967295, 192.0.2.75, 3/4, 1, example.org, string",
+        "name": "my-fancy-option",
+        "space": "my-fancy-space"
+      },
+      {
+        "code": 232,
+        "name": "my-encapsulating-option",
+        "space": "my-encapsulating-space"
+      }
+    ],
+
+    /*                       Custom option definitions                        */
+    // For kea-dhcp4, custom option definitions can be global or in a client
+    // class.
+    "option-def": [
+      // New option space allows for a new set of option codes.
+      // An empty option requires no "data" in "option-data". It's
+      // presence should be sufficient to trigger custom behavior.
+      {
+        "array": false,
+        "code": 1,
+        "encapsulate": "",
+        "name": "my-empty-option",
+        "record-types": "",
+        "space": "my-fancy-space",
+        "type": "empty"
+      },
+
+      // A custom type has "type" set to "record" and all data types (which need
+      // to be more than 1, otherwise you're better off using the type directly)
+      // are specified in "record-types". If "string" is part of them, it needs
+      // to be last.
+      {
+        "array": false,
+        "code": 224,
+        "encapsulate": "",
+        "name": "my-lengthy-option",
+        "record-types": "ipv4-address, psid, tuple, fqdn, string",
+        "space": "my-fancy-space",
+        "type": "record"
+      },
+
+      // Contains arrays of all types except strings since an array of strings
+      // is not a valid option definition.
+      {
+        "array": true,
+        "code": 254,
+        "encapsulate": "",
+        "name": "my-fancy-option",
+        "record-types": "int8, int16, int32, uint8, uint16, uint32, ipv4-address, psid, tuple, fqdn",
+        "space": "my-fancy-space",
+        "type": "record"
+      },
+
+      // A single encapsulating space can be used. An option containing any
+      // option from said space will now be unpacked successfully by Kea.
+      {
+        "array": false,
+        "code": 232,
+        "encapsulate": "my-fancy-space",
+        "name": "my-encapsulating-option",
+        "record-types": "",
+        "space": "my-encapsulating-space",
+        "type": "empty"
+      }
+    ],
+
+    "subnet4": [
+      /*                         DOCSIS3 option data                          */
+      // Headers are as defined in CL-SP-CANN-DHCP-Reg-I16-200715.
+      // "space" is required to be explicitly defined as "docsis3-v4"
+      {
+        "option-data": [
+          /*
+           0                   1                   2                   3
+           0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+          | CL_V4OPTION_ORO|  option-len  | req-opt-code-1| req-opt-code-2|
+          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+          |                              ...                              |
+          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+          option-code   CL_V4OPTION_ORO (1).
+
+          option-len    number of requested options.
+
+          req-opt-code-n The option code for an option requested by the client.
+
+          */
+          // Type: array of {uint8}
+          {
+            "code": 1,
+            "data": "32, 42",
+            "name": "oro",
+            "space": "docsis3-v4"
+          },
+
+          /*
+           0                   1                   2                   3
+           0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+          | option code |    option-len   | IPv4 address of TFTP server 1 |
+          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+          |  address of server 1 (cont.)  | IPv4 address of TFTP server 2 |
+          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+          |  address of server 2 (cont.)  |              ...
+          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+          .               ...             | IPv4 address of TFTP server n |
+          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+          |  address of server n (cont.)  |
+          +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+          option code      CL_VV4OPTION_TFTP_SERVERS (2)
+
+          option len       number of bytes for TFTP server IPv4 addresses (4*n for
+                           n servers)
+          */
+          // Type: array of {IPv4 address}
+          {
+            "code": 2,
+            "data": "192.0.2.76, 192.0.2.77",
+            "name": "tftp-servers",
+            "space": "docsis3-v4"
+          }
+        ],
+        "subnet": "192.0.2.0/24"
+      }
+    ]
+  }
+}
diff --git a/doc/examples/kea4/backends.json b/doc/examples/kea4/backends.json
new file mode 100644
index 0000000..40e0c39
--- /dev/null
+++ b/doc/examples/kea4/backends.json
@@ -0,0 +1,104 @@
+// This is an example configuration file for the DHCPv4 server in Kea.
+// It is a basic scenario with one IPv4 subnet configured. It demonstrates
+// how to configure Kea to use various backends to store leases:
+// - memfile
+// - MySQL
+// - PostgreSQL
+
+{ "Dhcp4":
+
+{
+// Kea is told to listen on eth0 interface only.
+  "interfaces-config": {
+    "interfaces": [ "eth0" ]
+  },
+
+// We need to specify lease type. Exactly one lease-database section
+// should be present. Make sure you uncomment only one.
+
+// 1. memfile backend. Leases information will be stored in flat CSV file.
+// This is the easiest backend to use as it does not require any extra
+// dependencies or services running.
+//  "lease-database": {
+//      "type": "memfile",
+//      "persist": true,
+//      "lfc-interval": 3600
+//  },
+
+// 2. MySQL backend. Leases will be stored in MySQL database. Make sure it
+// is up, running and properly initialized. See kea-admin documentation
+// for details on how to initialize the database. The only strictly required
+// parameters are type and name. If other parameters are not specified,
+// Kea will assume the database is available on localhost, that user and
+// password is not necessary to connect and that timeout is 5 seconds.
+// Kea must be compiled with --with-mysql option to use this backend.
+//  "lease-database": {
+//      "type": "mysql",
+//      "name": "keatest",
+//      "host": "localhost",
+//      "port": 3306,
+//      "user": "keatest",
+//      "password": "secret1",
+//      "reconnect-wait-time": 3000, // expressed in ms
+//      "max-reconnect-tries": 3,
+//      "on-fail": "stop-retry-exit",
+//      "connect-timeout": 3
+//  },
+
+// 3. PostgreSQL backend. Leases will be stored in PostgreSQL database. Make
+// sure it is up, running and properly initialized. See kea-admin documentation
+// for details on how to initialize the database. The only strictly required
+// parameters are type and name. If other parameters are not specified,
+// Kea will assume the database is available on localhost, that user and
+// password is not necessary to connect and that timeout is 5 seconds.
+// Kea must be compiled with --with-pgsql option to use this backend.
+//  "lease-database": {
+//      "type": "postgresql",
+//      "name": "keatest",
+//      "host": "localhost",
+//      "port": 5432,
+//      "user": "keatest",
+//      "password": "secret1",
+//      "reconnect-wait-time": 3000, // expressed in ms
+//      "max-reconnect-tries": 3,
+//      "on-fail": "stop-retry-exit",
+//      "connect-timeout": 3
+//  },
+
+// Addresses will be assigned with a lifetime of 4000 seconds.
+  "valid-lifetime": 4000,
+
+// Renew and rebind timers are commented out. This implies that options
+// 58 and 59 will not be sent to the client. In this case it is up to
+// the client to pick the timer values according to RFC2131. Uncomment the
+// timers to send these options to the client.
+//  "renew-timer": 1000,
+//  "rebind-timer": 2000,
+
+// The following list defines subnets. We have only one subnet
+// here. We tell Kea that it is directly available over local interface.
+  "subnet4": [
+    {
+       "pools": [ { "pool":  "192.0.2.1 - 192.0.2.200" } ],
+       "subnet": "192.0.2.0/24",
+       "interface": "eth0"
+    }
+  ],
+
+// The following configures logging. It assumes that messages with at
+// least informational level (info, warn, error and fatal) should be
+// logged to stdout.
+    "loggers": [
+        {
+            "name": "kea-dhcp4",
+            "output_options": [
+                {
+                    "output": "stdout"
+                }
+            ],
+            "severity": "INFO"
+        }
+    ]
+}
+
+}
diff --git a/doc/examples/kea4/classify.json b/doc/examples/kea4/classify.json
new file mode 100644
index 0000000..3f68c12
--- /dev/null
+++ b/doc/examples/kea4/classify.json
@@ -0,0 +1,142 @@
+// This is an example configuration file for the DHCPv4 server in Kea.
+// The purpose of this example is to showcase how clients can be classified.
+
+{ "Dhcp4": {
+
+// Kea is told to listen on eth0 interface only.
+  "interfaces-config": {
+      "interfaces": [ "eth0" ]
+  },
+
+// Let's use the simplest backend: memfile and use some reasonable values
+// for timers. They are of no concern for the classification demonstration.
+  "lease-database": { "type": "memfile" },
+  "renew-timer": 1000,
+  "rebind-timer": 2000,
+  "valid-lifetime": 4000,
+
+// This list defines several classes that incoming packets can be assigned to.
+// One packet can belong to zero or more classes.
+  "client-classes": [
+
+// The first class attempts to match the whole hardware address to a specific
+// value. All incoming packets with that MAC address will get a special
+// value of the option. If there are many hosts that require special
+// treatment, it is much better to use host reservations. However, doing
+// tricks with MAC addresses may prove useful in some cases, e.g.
+// by matching OUI to known values we can detect certain vendors.
+  {
+      "name": "special_snowflake",
+      "test": "pkt4.mac == 0x010203040506",
+      "option-data": [{
+          "name": "domain-name-servers",
+          "data": "127.0.0.1"
+      }]
+  },
+
+// Let's classify all incoming DISCOVER (message type 1) to a separate
+// class.
+  {
+      "name": "discovers",
+      "test": "pkt4.msgtype == 1"
+  },
+
+// Clients are supposed to set the transaction-id field to a random value.
+// Clients that send it with 0 are most likely broken. Let's mark them
+// as such.
+  {
+      "name": "broken",
+      "test": "pkt4.transid == 0"
+  },
+
+// Let's pick VoIP phones. Those that send their class identifiers
+// as Aastra, should belong to VoIP class. For a list of all options,
+// see www.iana.org/assignments/bootp-dhcp-parameters/.
+// In this particular class, we want to set specific values
+// of certain DHCPv4 fields. If the incoming packet matches the
+// test, those fields will be set in outgoing responses.
+// The option 43 is defined to encapsulate suboption in the aastra space.
+  {
+      "name": "VoIP",
+      "test": "substring(option[60].hex,0,6) == 'Aastra'",
+      "next-server": "192.0.2.254",
+      "server-hostname": "hal9000",
+      "boot-file-name": "/dev/null",
+      "option-def": [ {
+          "name": "vendor-encapsulated-options",
+          "code": 43,
+          "type": "empty",
+          "encapsulate": "aastra" } ]
+  }
+
+  ],
+
+// The following list defines subnets. For some subnets we defined
+// a class that is allowed in that subnet. If not specified,
+// everyone is allowed. When a class is specified, only packets belonging
+// to that class are allowed for that subnet.
+  "subnet4": [
+    // This one is for VoIP devices only.
+    {
+        "pools": [ { "pool":  "192.0.2.1 - 192.0.2.200" } ],
+        "subnet": "192.0.2.0/24",
+        "client-class": "VoIP",
+        "interface": "eth0"
+    },
+
+    // This one doesn't have any client-class specified, so everyone
+    // is allowed in. The normal subnet selection rules still apply,
+    // though. There is also a static class reservation for a client
+    // using MAC address 1a:1b:1c:1d:1e:1f. This client will always
+    // be assigned to this class.
+    {
+        "pools": [ { "pool":  "192.0.3.1 - 192.0.3.200" } ],
+        "subnet": "192.0.3.0/24",
+        "reservations": [
+        {
+            "hw-address": "1a:1b:1c:1d:1e:1f",
+            "client-classes": [ "VoIP" ]
+        } ],
+        "interface": "eth0"
+    },
+
+    // The following list defines a subnet with pools. For some pools
+    // we defined a class that is allowed in that pool. If not specified
+    // everyone is allowed. When a class is specified, only packets belonging
+    // to that class are allowed for that pool.
+    {
+        "pools": [
+           // This one is for VoIP devices only.
+           {
+              "pool":  "192.0.4.1 - 192.0.4.200",
+              "client-class": "VoIP"
+           },
+
+           // This one doesn't have any client-class specified,
+           // so everyone is allowed in.
+           {
+               "pool":  "192.0.5.1 - 192.0.5.200"
+           } ],
+
+        "subnet": "192.0.4.0/23",
+        "interface": "eth1"
+    }
+  ],
+
+// The following configures logging. It assumes that messages with at
+// least informational level (info, warn, error and fatal) should be
+// logged to stdout.
+    "loggers": [
+        {
+            "name": "kea-dhcp4",
+            "output_options": [
+                {
+                    "output": "stdout"
+                }
+            ],
+            "severity": "INFO"
+        }
+    ]
+}
+
+}
diff --git a/doc/examples/kea4/classify2.json b/doc/examples/kea4/classify2.json
new file mode 100644
index 0000000..955e6bd
--- /dev/null
+++ b/doc/examples/kea4/classify2.json
@@ -0,0 +1,174 @@
+// This is an example configuration file for the DHCPv4 server in Kea.
+// The purpose of this example is to showcase how clients can be classified
+// with advanced features.
+
+{ "Dhcp4": {
+
+// Kea is told to listen on eth0 interface only.
+  "interfaces-config": {
+      "interfaces": [ "eth0" ]
+  },
+
+// Let's use the simplest backend: memfile and use some reasonable values
+// for timers. They are of no concern for the classification demonstration.
+  "lease-database": { "type": "memfile" },
+  "renew-timer": 1000,
+  "rebind-timer": 2000,
+  "valid-lifetime": 4000,
+
+// This list defines several classes that incoming packets can be assigned to.
+// One packet can belong to zero or more classes.
+  "client-classes": [
+
+// This class is required by the second subnet and is evaluated only
+// if it is required. The test expression returns true.
+// Note it is not possible to depend on VoIP class because it is not yet
+// defined.
+  {
+      "name": "second_subnet",
+      "only-if-required": true,
+      "test": "member('ALL')",
+      "option-data": [{
+          "name": "domain-name-servers",
+          "data": "127.0.0.1"
+      }]
+  },
+
+// Let's classify all incoming DISCOVER (message type 1) to a separate
+// class.
+  {
+      "name": "discovers",
+      "test": "pkt4.msgtype == 1"
+  },
+
+// Clients are supposed to set the transaction-id field to a random value.
+// Clients that send it with 0 are most likely broken. Let's mark them
+// as such.
+  {
+      "name": "broken",
+      "test": "pkt4.transid == 0"
+  },
+
+// Let's pick VoIP phones. Those that send their class identifiers
+// as Aastra, should belong to VoIP class. For a list of all options,
+// see www.iana.org/assignments/bootp-dhcp-parameters/.
+// In this particular class, we want to set specific values
+// of certain DHCPv4 fields. If the incoming packet matches the
+// test, those fields will be set in outgoing responses.
+// The option 43 is defined to encapsulate suboption in the aastra space.
+  {
+      "name": "VoIP",
+      "test": "substring(option[60].hex,0,6) == 'Aastra'",
+      "next-server": "192.0.2.254",
+      "server-hostname": "hal9000",
+      "boot-file-name": "/dev/null",
+      "option-def": [ {
+          "name": "vendor-encapsulated-options",
+          "code": 43,
+          "type": "empty",
+          "encapsulate": "aastra" } ]
+  },
+
+// Both a VoIP phone (by evaluation or host reservation) and has a host
+// reservation.
+  {
+      "name": "VoIP_host",
+      "test": "member('VoIP') and member('KNOWN')",
+      "server-hostname": "hal9001"
+  }
+
+  ],
+
+// The following list defines subnets. For some subnets we defined
+// a class that is allowed in that subnet. If not specified,
+// everyone is allowed. When a class is specified, only packets belonging
+// to that class are allowed for that subnet.
+  "subnet4": [
+    {
+// This one is for VoIP devices only.
+        "pools": [ { "pool":  "192.0.2.1 - 192.0.2.200" } ],
+        "subnet": "192.0.2.0/24",
+        "client-class": "VoIP",
+        "interface": "eth0"
+    },
+// This one doesn't have any client-class specified, so everyone
+// is allowed in. The normal subnet selection rules still apply,
+// though. There is also a static class reservation for a client
+// using MAC address 1a:1b:1c:1d:1e:1f. This client will always
+// be assigned to this class.
+    {
+        "pools": [ { "pool":  "192.0.3.1 - 192.0.3.200" } ],
+        "subnet": "192.0.3.0/24",
+        "reservations": [
+        {
+            "hw-address": "1a:1b:1c:1d:1e:1f",
+            "client-classes": [ "VoIP" ]
+        } ],
+        "interface": "eth0",
+        "require-client-classes": [ "second_subnet" ]
+    },
+
+// The following list defines a subnet with pools. For some pools
+// we defined a class that is allowed in that pool. If not specified
+// everyone is allowed. When a class is specified, only packets belonging
+// to that class are allowed for that pool.
+     {
+        "pools": [
+           {
+// This one is for VoIP devices only.
+              "pool":  "192.0.4.1 - 192.0.4.200",
+              "client-class": "VoIP"
+           },
+// This one doesn't have any client-class specified, so everyone
+// is allowed in.
+           {
+               "pool":  "192.0.5.1 - 192.0.5.200"
+           } ],
+           "subnet": "192.0.4.0/23",
+           "interface": "eth1"
+        },
+// This subnet is divided in two pools for unknown and known
+// (i.e. which have a reservation) clients. The built-in KNOWN and
+// UNKNOWN classes are set or not at host reservation lookup (KNOWN if
+// this returns something, UNKNOWN if this finds nothing) and client
+// classes depending on it are evaluated.
+// This happens after subnet selection and before address allocation
+// from pools.
+        {
+           "pools": [
+                {
+                   "pool": "192.0.8.100 - 192.0.8.200",
+                   "client-class": "UNKNOWN"
+                },
+                {
+                   "pool": "192.0.9.100 - 192.0.9.200",
+                   "client-class": "KNOWN"
+                }
+            ],
+            "subnet": "192.0.8.0/23",
+            "reservations": [
+                {  "hw-address": "00:00:00:11:22:33", "hostname": "h1" },
+                {  "hw-address": "00:00:00:44:55:66", "hostname": "h4" },
+                {  "hw-address": "00:00:00:77:88:99", "hostname": "h7" },
+                {  "hw-address": "00:00:00:aa:bb:cc", "hostname": "ha" }
+            ]
+        }
+  ],
+
+// The following configures logging. It assumes that messages with at
+// least informational level (info, warn, error and fatal) should be
+// logged to stdout.
+    "loggers": [
+        {
+            "name": "kea-dhcp4",
+            "output_options": [
+                {
+                    "output": "stdout"
+                }
+            ],
+            "severity": "INFO"
+        }
+    ]
+}
+
+}
diff --git a/doc/examples/kea4/comments.json b/doc/examples/kea4/comments.json
new file mode 100644
index 0000000..a5cfbdc
--- /dev/null
+++ b/doc/examples/kea4/comments.json
@@ -0,0 +1,113 @@
+// This is an example configuration file for the DHCPv4 server in Kea.
+// It uses embedded (i.e., which will be included in configuration objects
+// and not stripped by at lexical analysis) comments.
+
+{ "Dhcp4":
+
+{
+   // Global scope
+   "comment": "A DHCPv4 server",
+
+   // In interface config
+   "interfaces-config": {
+       "comment": "Use wildcard",
+       "interfaces": [ "*" ] },
+
+   // In option definitions
+   "option-def": [ {
+       "comment": "An option definition",
+       "name": "foo",
+       "code": 100,
+       "type": "ipv4-address",
+       "space": "isc"
+    } ],
+
+   // In option data
+   "option-data": [ {
+       "comment": "Set option value",
+       "name": "dhcp-message",
+       "data": "ABCDEF0105",
+       "csv-format": false
+    } ],
+
+   // In client classes
+   "client-classes": [
+       {
+          "comment": "match all",
+          "name": "all",
+          "test": "'' == ''"
+       },
+       // Of course comments are optional
+       {
+          "name": "none"
+       },
+       // A comment and a user-context can be specified
+       {
+          "comment": "a comment",
+          "name": "both",
+          "user-context": {
+              "version": 1
+          }
+       }
+   ],
+
+   // In control socket (more for the agent)
+   "control-socket": {
+       "socket-type": "unix",
+       "socket-name": "/tmp/kea4-ctrl-socket",
+       "user-context": { "comment": "Indirect comment" }
+   },
+
+   // In shared networks
+   "shared-networks": [ {
+       "comment": "A shared network",
+       "name": "foo",
+
+       // In subnets
+       "subnet4": [
+         {
+           "comment": "A subnet",
+           "subnet": "192.0.1.0/24",
+           "id": 100,
+
+           // In pools
+           "pools": [
+             {
+                "comment": "A pool",
+                "pool": "192.0.1.1-192.0.1.10"
+             }
+           ],
+
+           // In host reservations
+           "reservations": [
+             {
+                "comment": "A host reservation",
+                "hw-address": "AA:BB:CC:DD:EE:FF",
+                "hostname": "foo.example.com",
+
+                // Again in an option data
+                "option-data": [ {
+                    "comment": "An option in a reservation",
+                    "name": "domain-name",
+                    "data": "example.com"
+                } ]
+             }
+           ]
+         }
+       ]
+    } ],
+
+   // In dhcp ddns
+   "dhcp-ddns": {
+       "comment": "No dynamic DNS",
+       "enable-updates": false
+   },
+
+   // In loggers
+   "loggers": [ {
+       "comment": "A logger",
+       "name": "kea-dhcp4"
+   } ]
+}
+
+}
diff --git a/doc/examples/kea4/config-backend.json b/doc/examples/kea4/config-backend.json
new file mode 100644
index 0000000..aae0f34
--- /dev/null
+++ b/doc/examples/kea4/config-backend.json
@@ -0,0 +1,91 @@
+// This is an example configuration file for the DHCPv4 server in Kea.
+// It demonstrates how to enable Kea Configuration Backend using MySQL.
+// It requires that libdhcp_mysql_cb.so library is available and
+// optionally libdhcp_cb_cmds.so hooks library.
+
+{ "Dhcp4":
+
+{
+    // Set the server tag for the configuration backend. This instance will
+    // be named server1. Every configuration element that is applicable to
+    // either "all" or "server1" will be used by this instance.
+    "server-tag": "server1",
+
+    // Kea is told to listen on eth0 interface only.
+    "interfaces-config": {
+        "interfaces": [ "eth0" ]
+    },
+
+    // Use memfile lease database backend.
+    "lease-database": {
+        "type": "memfile",
+        "lfc-interval": 3600
+    },
+
+    // This parameter controls how the server accesses the configuration
+    // database. Currently only one database type is available - "mysql".
+    // It requires that libdhcp_mysql_cb.so hooks library is loaded.
+    "config-control": {
+        // A list of database backends to connect to. Currently, it is limited
+        // to a single backend.
+        "config-databases": [
+            {
+                "type": "mysql",
+                "reconnect-wait-time": 3000, // expressed in ms
+                "max-reconnect-tries": 3,
+                "name": "kea",
+                "user": "kea",
+                "password": "kea",
+                "host": "localhost",
+                "port": 3306
+            }
+        ],
+        // Controls how often the server polls the database for the
+        // configuration updates. The setting below implies that it
+        // will take up to approx. 20 seconds for the server to
+        // discover and fetch configuration changes.
+        "config-fetch-wait-time": 20
+    },
+
+    // This defines a control socket. If defined, Kea will open a UNIX socket
+    // and will listen for incoming commands. See section 17 of the Kea ARM for
+    // details.
+    "control-socket": {
+        "socket-type": "unix",
+        "socket-name": "/tmp/kea4-ctrl-socket"
+    },
+
+    // Hooks libraries that enable configuration backend are loaded.
+    "hooks-libraries": [
+        // The libdhcp_mysql_cb.so is required to use MySQL Configuration
+        // Backend.
+        {
+            "library": "/usr/local/lib/kea/hooks/libdhcp_mysql_cb.so"
+        }
+        // The libdhcp_cb_cmds.so is optional. It allows for managing the
+        // configuration in the database. If this library is not loaded,
+        // the configuration can be managed directly using available
+        // tools that work directly with the MySQL database.
+        //,{
+            // "library": "/usr/local/lib/kea/hooks/libdhcp_cb_cmds.so"
+        //}
+    ],
+
+    // The following configures logging. It assumes that messages with at
+    // least informational level (info, warn, error and fatal) should be
+    // logged to stdout. Alternatively, you can specify stderr here, a filename
+    // or 'syslog', which will store output messages via syslog.
+    "loggers": [
+        {
+            "name": "kea-dhcp4",
+            "output_options": [
+                {
+                    "output": "stdout"
+                }
+            ],
+            "severity": "INFO"
+        }
+    ]
+}
+
+}
diff --git a/doc/examples/kea4/dhcpv4-over-dhcpv6.json b/doc/examples/kea4/dhcpv4-over-dhcpv6.json
new file mode 100644
index 0000000..52cdc1c
--- /dev/null
+++ b/doc/examples/kea4/dhcpv4-over-dhcpv6.json
@@ -0,0 +1,46 @@
+// This is an example configuration file for the DHCPv4 server of
+// DHCPv4-over-DHCPv6 tests in Kea.
+
+{
+
+// DHCPv4 conf
+"Dhcp4":
+{
+  "interfaces-config": {
+    "interfaces": [ "eth0" ]
+  },
+
+  "lease-database": {
+      "type": "memfile",
+      "name": "leases4",
+      "lfc-interval": 3600
+  },
+
+  "valid-lifetime": 4000,
+
+  "subnet4": [
+   {    "subnet": "10.10.10.0/24",
+// Don't forget the "4o6-" before "interface" here!
+        "4o6-interface": "eth0",
+        "4o6-subnet": "2001:db8:1:1::/64",
+        "pools": [ { "pool": "10.10.10.100 - 10.10.10.199" } ] }
+  ],
+
+// This enables DHCPv4-over-DHCPv6 support
+  "dhcp4o6-port": 6767,
+
+  "loggers": [
+    {
+      "name": "kea-dhcp4",
+      "output_options": [
+          {
+            "output": "/tmp/kea-dhcp4.log"
+          }
+      ],
+      "severity": "DEBUG",
+      "debuglevel": 0
+    }
+  ]
+}
+
+}
diff --git a/doc/examples/kea4/global-reservations.json b/doc/examples/kea4/global-reservations.json
new file mode 100644
index 0000000..d25200c
--- /dev/null
+++ b/doc/examples/kea4/global-reservations.json
@@ -0,0 +1,177 @@
+// This is an example configuration file for the DHCPv4 server in Kea.
+// It demonstrates how global host reservations can be configured.
+// The global reservations are not associated with any subnet. They
+// are assigned regardless of the subnet to which the DHCP client belongs.
+// Global reservations are assigned to the DHCP clients using the
+// same host identifier types as subnet specific reservations. This file
+// contains multiple examples of host reservations using different
+// identifier types, e.g. MAC address, client identifier etc.
+{ "Dhcp4":
+
+{
+// Kea is told to listen on eth0 interface only.
+  "interfaces-config": {
+    "interfaces": [ "eth0" ]
+  },
+
+// We need to specify the database used to store leases. As of June
+// 2022, three database backends are supported: MySQL, PostgreSQL and
+// the in-memory database, Memfile.  We'll use memfile because it doesn't
+// require any prior set up.
+  "lease-database": {
+      "type": "memfile",
+      "lfc-interval": 3600
+  },
+
+// Addresses will be assigned with a lifetime of 4000 seconds.
+  "valid-lifetime": 4000,
+
+// Renew and rebind timers are commented out. This implies that options
+// 58 and 59 will not be sent to the client. In this case it is up to
+// the client to pick the timer values according to RFC2131. Uncomment the
+// timers to send these options to the client.
+//  "renew-timer": 1000,
+//  "rebind-timer": 2000,
+
+// Kea supports reservations by several different types of identifiers:
+// hw-address (hardware/MAC address of the client), duid (DUID inserted by the
+// client), client-id (client identifier inserted by the client), circuit-id
+// (circuit identifier inserted by the relay agent) and flex-id (flexible
+// identifier available when flex_id hook library is loaded). When told to do
+// so, Kea can check for all of those identifier types, but it takes a costly
+// database lookup to do so. It is therefore useful from a performance
+// perspective to use only the reservation types that are actually used in a
+// given network.
+
+// The example below is not optimal from a performance perspective, but it
+// nicely showcases the host reservation capabilities. Please use the minimum
+// set of identifier types used in your network.
+  "host-reservation-identifiers": [ "circuit-id", "hw-address", "duid",
+                                    "client-id", "flex-id" ],
+
+// This directive tells Kea that reservations are global. Note that this
+// can also be specified at shared network and/or subnet level.
+// "reservation-mode": "global",
+// It is replaced by the "reservations-global", "reservations-in-subnet" and
+// "reservations-out-of-pool" parameters.
+
+// Specify if server should lookup global reservations.
+  "reservations-global": true,
+
+// Specify if server should lookup in-subnet reservations.
+  "reservations-in-subnet": false,
+
+// Specify if server can assume that all reserved addresses
+// are out-of-pool.
+// Ignored when reservations-in-subnet is false.
+// If specified, it is inherited by "shared-networks" and "subnet4" levels.
+  "reservations-out-of-pool": false,
+
+// Define several global host reservations.
+  "reservations": [
+
+// This is a reservation for a specific hardware/MAC address. It's a very
+// simple reservation: just an address and nothing else.
+// Note it is not recommended but still allowed to reverse addresses at
+// the global scope: as it breaks the link between the reservation and
+// the subnet it can lead to a client localized in another subnet than
+// its address belongs to.
+    {
+        "hw-address": "1a:1b:1c:1d:1e:1f",
+        "ip-address": "192.0.2.201"
+    },
+
+// This is a reservation for a specific client-id. It also shows
+// the this client will get a reserved hostname. A hostname can be defined
+// for any identifier type, not just client-id. Either a hostname or
+// an address is required.
+    {
+        "client-id": "01:11:22:33:44:55:66",
+        "hostname": "special-snowflake"
+    },
+
+// The third reservation is based on DUID. This reservation also
+// defines special option values for this particular client. If
+// the domain-name-servers option would have been defined on a global,
+// subnet or class level, the host specific values take precedence for
+// this particular DHCP client.
+    {
+        "duid": "01:02:03:04:05",
+        "ip-address": "192.0.2.203",
+        "option-data": [ {
+            "name": "domain-name-servers",
+            "data": "10.1.1.202,10.1.1.203"
+        } ]
+    },
+
+// The fourth reservation is based on circuit-id. This is an option inserted
+// by the relay agent that forwards the packet from client to the server.
+// In this example the host is also assigned vendor specific options.
+    {
+        "circuit-id": "01:11:22:33:44:55:66",
+        "ip-address": "192.0.2.204",
+        "option-data": [
+            {
+                "name": "vivso-suboptions",
+                "data": "4491"
+            },
+            {
+                "name": "tftp-servers",
+                "space": "vendor-4491",
+                "data": "10.1.1.202,10.1.1.203"
+            }
+        ]
+    },
+
+// This reservation is for a client that needs specific DHCPv4 fields to be
+// set. Three supported fields are next-server, server-hostname and
+// boot-file-name
+    {
+        "client-id": "01:0a:0b:0c:0d:0e:0f",
+        "ip-address": "192.0.2.205",
+        "next-server": "192.0.2.1",
+        "server-hostname": "hal9000",
+        "boot-file-name": "/dev/null"
+    },
+
+// This reservation is using flexible identifier. Instead of relying
+// on specific field, sysadmin can define an expression similar to what
+// is used for client classification,
+// e.g. substring(relay[0].option[17],0,6). Then, based on the value of
+// that expression for incoming packet, the reservation is matched.
+// Expression can be specified either as hex or plain text using single
+// quotes.
+// Note: flexible identifier requires flex_id hook library to be
+// loaded to work.
+    {
+        "flex-id": "'s0mEVaLue'",
+        "ip-address": "192.0.2.206"
+    }
+  ],
+
+  // Define a subnet.
+    "subnet4": [
+        {
+           "pools": [ { "pool":  "192.0.2.1 - 192.0.2.200" } ],
+           "subnet": "192.0.2.0/24",
+           "interface": "eth0"
+        }
+    ],
+
+// The following configures logging. It assumes that messages with at
+// least informational level (info, warn, error and fatal) should be
+// logged to stdout.
+    "loggers": [
+        {
+            "name": "kea-dhcp4",
+            "output_options": [
+                {
+                    "output": "stdout"
+                }
+            ],
+            "severity": "INFO"
+        }
+    ]
+}
+
+}
diff --git a/doc/examples/kea4/ha-load-balancing-primary.json b/doc/examples/kea4/ha-load-balancing-primary.json
new file mode 100644
index 0000000..ae730e5
--- /dev/null
+++ b/doc/examples/kea4/ha-load-balancing-primary.json
@@ -0,0 +1,225 @@
+// This is an example configuration of the Kea DHCPv4 server. It uses High
+// Availability hooks library and Lease Commands hooks library to enable
+// High Availability function for the DHCP server. Note that almost exactly
+// the same configuration must be used on the second server (partner).
+// The only difference is that "this-server-name" must be set to "server2"
+// on this other server. Also, the interface configuration depends on the
+// network settings of the particular machine.
+//
+// The servers using this configuration work in load balancing mode.
+{
+
+// DHCPv4 configuration starts here.
+"Dhcp4": {
+    // Add names of your network interfaces to listen on.
+    "interfaces-config": {
+        // The DHCPv4 server listens on this interface.
+        "interfaces": [ "eth0" ]
+    },
+
+    // Control socket is required for communication between the Control
+    // Agent and the DHCP server. High Availability requires Control Agent
+    // to be running because lease updates are sent over the RESTful
+    // API between the HA peers.
+    "control-socket": {
+        "socket-type": "unix",
+        "socket-name": "/tmp/kea4-ctrl-socket"
+    },
+
+    // Use Memfile lease database backend to store leases in a CSV file.
+    // Depending on how Kea was compiled, it may also support SQL databases
+    // (MySQL and/or PostgreSQL). Those database backends require more
+    // parameters, like name, host and possibly user and password.
+    // There are dedicated examples for each backend. See Section 7.2.2 "Lease
+    // Storage" for details.
+    "lease-database": {
+        // Memfile is the simplest and easiest backend to use. It's an in-memory
+        "type": "memfile"
+    },
+
+    // Client classes will associate address pools with certain servers taking
+    // part in providing High Availability.
+    "client-classes": [
+        // phones class
+        {
+            "name": "phones",
+            "test": "substring(option[60].hex,0,6) == 'Aastra'"
+        },
+        // laptops are everything but phones.
+        {
+            "name": "laptops",
+            "test": "not member('phones')"
+        },
+        // Some phones will be handled by server1. Whether the HA_server1
+        // or HA_server2 is assigned for the client is a matter of load
+        // balancing performed by the HA hooks library.
+        {
+            "name": "phones_server1",
+            "test": "member('phones') and member('HA_server1')"
+        },
+        // Some phones will be handled by server2.
+        {
+            "name": "phones_server2",
+            "test": "member('phones') and member('HA_server2')"
+        },
+        // Some laptops will be handled by server1.
+        {
+            "name": "laptops_server1",
+            "test": "member('laptops') and member('HA_server1')"
+        },
+        // Some laptops will be handled by server2.
+        {
+            "name": "laptops_server2",
+            "test": "member('laptops') and member('HA_server2')"
+        }
+    ],
+
+
+    // HA requires two hooks libraries to be loaded: libdhcp_lease_cmds.so and
+    // libdhcp_ha.so. The former handles incoming lease updates from the HA peers.
+    // The latter implements high availability feature for Kea.
+    "hooks-libraries": [
+        // The lease_cmds library must be loaded because HA makes use of it to
+        // deliver lease updates to the server as well as synchronize the
+        // lease database after failure.
+        {
+            "library": "/opt/lib/kea/hooks/libdhcp_lease_cmds.so",
+            "parameters": { }
+        },
+        {
+            // The HA hooks library should be loaded.
+            "library": "/opt/lib/kea/hooks/libdhcp_ha.so",
+            "parameters": {
+                // High Availability configuration is specified for the HA hook library.
+                // Each server should have the same HA configuration, except for the
+                // "this-server-name" parameter.
+                "high-availability": [ {
+                    // This parameter points to this server instance. The respective
+                    // HA peers must have this parameter set to their own names.
+                    "this-server-name": "server1",
+                    // The HA mode is set to load-balancing. In this mode, the active
+                    // servers share the traffic (50/50).
+                    "mode": "load-balancing",
+                    // Heartbeat is to be sent every 10 seconds if no other control
+                    // commands are transmitted.
+                    "heartbeat-delay": 10000,
+                    // Maximum time for partner's response to a heartbeat, after which
+                    // failure detection is started. This is specified in milliseconds.
+                    "max-response-delay": 60000,
+                    // The following parameters control how the server detects the
+                    // partner's failure. The ACK delay sets the threshold for the
+                    // 'secs' field of the received discovers. This is specified in
+                    // milliseconds.
+                    "max-ack-delay": 5000,
+                    // This specifies the number of clients which send messages to
+                    // the partner but appear to not receive any response.
+                    "max-unacked-clients": 5,
+                    // This specifies the maximum timeout (in milliseconds) for the server
+                    // to complete sync. If you have a large deployment (high tens or
+                    // hundreds of thausands of clients), you may need to increase it
+                    // further. The default value is 60000ms (60 seconds).
+                    "sync-timeout": 60000,
+                    "peers": [
+                         // This is the configuration of this server instance.
+                         {
+                             "name": "server1",
+                             // This specifies the URL of our server instance. The
+                             // Control Agent must run along with our DHCPv4 server
+                             // instance and the "http-host" and "http-port" must be
+                             // set to the corresponding values.
+                             "url": "http://192.168.56.33:8000/",
+                             // This server is primary. The other one must be
+                             // secondary.
+                             "role": "primary"
+                         },
+                         // This is the configuration of our HA peer.
+                         {
+                             "name": "server2",
+                             // Specifies the URL on which the partner's control
+                             // channel can be reached. The Control Agent is required
+                             // to run on the partner's machine with "http-host" and
+                             // "http-port" values set to the corresponding values.
+                             "url": "http://192.168.56.66:8000/",
+                             // The partner is a secondary. Our is primary.
+                             "role": "secondary"
+                         }
+                     ]
+                 } ]
+            }
+        }
+    ],
+
+    // This example contains a single subnet declaration.
+    "subnet4": [
+        {
+            // Subnet prefix.
+            "subnet": "192.0.3.0/24",
+
+            // Specify four address pools.
+            "pools": [
+                {
+                    "pool": "192.0.3.100 - 192.0.3.125",
+                    "client-class": "phones_server1"
+                },
+                {
+                    "pool": "192.0.3.126 - 192.0.3.150",
+                    "client-class": "laptops_server1"
+                },
+                {
+                    "pool": "192.0.3.200 - 192.0.3.225",
+                    "client-class": "phones_server2"
+                },
+                {
+                    "pool": "192.0.3.226 - 192.0.3.250",
+                    "client-class": "laptops_server2"
+                }
+            ],
+
+            // These are options that are subnet specific. In most cases,
+            // you need to define at least routers option, as without this
+            // option your clients will not be able to reach their default
+            // gateway and will not have Internet connectivity.
+            "option-data": [
+                {
+                    // For each IPv4 subnet you most likely need to specify at
+                    // least one router.
+                    "name": "routers",
+                    "data": "192.0.3.1"
+                }
+            ],
+
+            // This subnet will be selected for queries coming from the following
+            // IP address.
+            "relay": { "ip-address": "192.168.56.1" }
+        }
+    ],
+
+    // Logging configuration starts here.
+    "loggers": [
+    {
+        // This section affects kea-dhcp4, which is the base logger for DHCPv4
+        // component. It tells DHCPv4 server to write all log messages (on
+        // severity INFO or more) to a file.
+        "name": "kea-dhcp4",
+        "output_options": [
+            {
+                "output": "stdout"
+
+            }
+        ],
+        "severity": "INFO"
+    },
+    {
+        // This section specifies configuration of the HA hooks library specific
+        // logger.
+        "name": "kea-dhcp4.ha-hooks",
+        "output_options": [
+            {
+                "output": "stdout"
+            }
+        ],
+        "severity": "INFO"
+    }
+  ]
+}
+}
diff --git a/doc/examples/kea4/hooks-radius.json b/doc/examples/kea4/hooks-radius.json
new file mode 100644
index 0000000..f00190e
--- /dev/null
+++ b/doc/examples/kea4/hooks-radius.json
@@ -0,0 +1,224 @@
+// This is an example configuration file for the DHCPv4 server in Kea
+// illustrating the configuration of the RADIUS and Host Cache hooks libraries.
+//
+// It is not intended to be used as is. It tries to showcase some of the
+// parameters available.
+//
+// To use this configuration file, you need to have both RADIUS and
+// Host Cache hooks. These are currently available to support customers only.
+//
+// clients get a wine name (option AOP code 250) divided into red and white.
+// Expensive brands have a host entry, i.e. a reserved address.
+//
+// Names
+//
+// brouilly (red)
+// chablis (white)
+// chambertin (red, expensive)
+// chinon (red)
+// chiroubles (red)
+// condrieu (white)
+// cornas (red)
+// corton (red)
+// fleurie (red)
+// givry (red)
+// margaux (red, expensive)
+// meursault (white)
+// montrachet (white, expensive)
+// morgon (red)
+// muscadet (white)
+// petrus (red, expensive)
+// riesling (white)
+// romanee (red, expensive)
+// sylvaner (white)
+// yquem (white, expensive)
+//
+// Address space is 192.0.2.0/24 with 10-99 for reds and 110-199 for whites.
+//
+// Reservations are given here in Kea/JSON style but they must be
+// in the RADIUS server configuration:
+//
+//       {
+//          "flex-id": "'chambertin'",
+//          "ip-address": "192.0.2.10"
+//       },
+//       {
+//          "flex-id": "'margaux'",
+//          "ip-address": "192.0.2.11"
+//       },
+//       {
+//          "flex-id": "'petrus'",
+//          "ip-address": "192.0.2.12"
+//       },
+//       {
+//          "flex-id": "'romanee'",
+//          "ip-address": "192.0.2.13"
+//       },
+//       {
+//          "flex-id": "'montrachet'",
+//          "ip-address": "192.0.2.110"
+//       },
+//       {
+//          "flex-id": "'yquem'",
+//          "ip-address": "192.0.2.111"
+//       }
+//
+
+{"Dhcp4":
+
+{
+  // Kea is told to listen on specific interfaces only.
+  "interfaces-config": {
+    // You should probably list your network interfaces here (e.g. "eth1961")
+    "interfaces": [ "eth1961" ]
+  },
+
+  // Set up the storage for leases.
+  "lease-database": {
+    "type": "memfile"
+  },
+
+  // Note there is hosts-database defined. RADIUS and Host Cache libraries
+  // will create them dynamically.
+
+  // RADIUS uses flex-id reservations, so restrict Kea to use flex-id only.
+  "host-reservation-identifiers": [ "flex-id" ],
+
+  // Define the AOP option.
+  "option-def": [ {
+      "name": "AOP",
+      "code": 250,
+      "type": "string" } ],
+
+  // Define red and white client classes.
+  // If they are not defined we can get spurious warnings.
+  "client-classes": [
+      { "name": "red" },
+      { "name": "white" } ],
+
+  // Define a subnet.
+  "subnet4": [ {
+      // Set the subnet ID (aka RADIUS NAS port).
+      "id": 14,
+      "subnet": "192.0.2.0/24",
+      "interface": "eth1961",
+      "pools": [
+         {
+            // Red pool (10-19 are for reservations)
+            "pool": "192.0.2.20-192.0.2.99",
+            "client-class": "red"
+         },
+         {
+            // White pool (110-119 are for reservations)
+            "pool": "192.0.2.120-192.0.2.199",
+            "client-class": "white"
+         }
+
+          // Note there are not pools available to anyone. This is
+          // important to note. This means that to get an address, the
+          // client needs to belong to red class, to white class or
+          // have an address reserved.
+      ]
+    } ],
+
+  // Set up the hooks libraries.
+  "hooks-libraries": [
+     {
+        // Load the flex-id hook library.
+        "library": "/usr/local/lib/kea/hooks/libdhcp_flex_id.so",
+
+        "parameters": {
+            // Take the ID from the AOP option.
+            "identifier-expression": "option[250].text",
+
+            // Replace the client ID in queries by the flex-id.
+            // Currently required by access code.
+            // Required for accounting as it will become the lease ID too.
+            "replace-client-id": true
+        }
+     },
+     {
+         // Load the host cache hook library. It is needed by the RADIUS
+         // library to keep the attributes from authorization to later user
+         // for accounting.
+         "library": "/usr/local/lib/kea/hooks/libdhcp_host_cache.so"
+     },
+     {
+         // Load the RADIUS hook library.
+         "library": "/usr/local/lib/kea/hooks/libdhcp_radius.so",
+
+         "parameters": {
+             // If do not use RFC 4361
+             // "extract-duid": false,
+
+             // If have conflicting subnets
+             // "reselect-subnet-pool": true,
+
+             // Strip the 0 type added by flex-id
+             "client-id-pop0": true,
+
+             // flex Id is printable (far easier for the RADIUS server config)
+             // Without this it will be in hexadecimal...
+             "client-id-printable": true,
+
+             // Use the flex-id.
+             "identifier-type4": "flex-id",
+
+             // Configure an access (aka authentication/authorization) server.
+             "access": {
+
+                 // This starts the list of access servers
+                 "servers": [
+                     {
+                         // These are parameters for the first (and only) access server
+                         "name": "127.0.0.1",
+                         "port": 1812,
+                         "secret": "secret"
+                     }
+                     // Additional access servers could be specified here
+                 ],
+
+                 // This define a list of additional attributes Kea will send to each
+                 // access server in Access-Request.
+                 "attributes": [
+                 {
+                     // This attribute is identified by name (must be present in the
+                     // dictionary) and has static value (i.e. the same value will be
+                     // sent to every server for every packet)
+                     "name": "Password",
+                     "data": "mysecretpassword"
+                 },
+                 {
+                     // It's also possible to specify an attribute using its type,
+                     // rather than a name. 77 is Connect-Info. The value is specified
+                     // using hex. Again, this is a static value. It will be sent the
+                     // same for every packet and to every server.
+                     "type": 77,
+                     "raw": "65666a6a71"
+                 },
+                 {
+                     // This example shows how an expression can be used to send dynamic
+                     // value. The expression (see Section 13) may take any value from
+                     // the incoming packet or even its metadata (e.g. the interface
+                     // it was received over from)
+                     "name": "Configuration-Token",
+                     "expr": "pkt.iface"
+                 }
+                 ] // End of attributes
+              },
+
+             // Configure an accounting server.
+             "accounting": {
+                 "servers": [ {
+                         "name": "127.0.0.1",
+                         "port": 1813,
+                         "secret": "secret"
+                     }
+                ]
+             }
+         }
+     }
+     ]
+}
+
+}
diff --git a/doc/examples/kea4/hooks.json b/doc/examples/kea4/hooks.json
new file mode 100644
index 0000000..0d6e29b
--- /dev/null
+++ b/doc/examples/kea4/hooks.json
@@ -0,0 +1,49 @@
+// This is an example configuration file for the DHCPv4 server in Kea
+// illustrating the configuration of hooks libraries.  It uses a basic scenario
+// of one IPv4 subnet configured with the default values for all parameters.
+
+{"Dhcp4":
+
+{
+// Kea is told to listen on the eth0 interface only.
+  "interfaces-config": {
+    "interfaces": [ "eth0" ]
+  },
+
+// Set up the storage for leases.
+  "lease-database": {
+    "type": "memfile"
+  },
+
+  "valid-lifetime": 1800,
+
+// Define a single subnet.
+  "subnet4": [
+    {
+      "pools": [ { "pool": "192.0.2.1 - 192.0.2.200" } ],
+      "subnet": "192.0.2.0/24",
+      "interface": "eth0"
+    }
+  ],
+
+// Set up the hooks libraries.  For this example, we assume that two libraries
+// are loaded, called "security" and "charging".  Note that order is important:
+// "security" is specified first so if both libraries supply a hook function
+// for a given hook, the function in "security" will be called before that in
+// "charging".
+
+  "hooks-libraries": [
+     {
+        "library": "/opt/lib/security.so"
+     },
+     {
+         "library": "/opt/lib/charging.so",
+         "parameters": {
+             "path": "/var/lib/kea",
+             "base-name": "kea-forensic6"
+         }
+     }
+  ]
+}
+
+}
diff --git a/doc/examples/kea4/leases-expiration.json b/doc/examples/kea4/leases-expiration.json
new file mode 100644
index 0000000..c40dd5d
--- /dev/null
+++ b/doc/examples/kea4/leases-expiration.json
@@ -0,0 +1,72 @@
+// This is an example configuration file for the DHCPv4 server in Kea.
+// It provides parameters controlling processing of expired leases,
+// a.k.a. leases reclamation.
+
+{ "Dhcp4":
+
+{
+// Kea is told to listen on eth0 interface only.
+  "interfaces-config": {
+    "interfaces": [ "eth0" ]
+  },
+
+// We need to specify the database used to store leases. As of
+// June 2022, three database backends are supported: MySQL,
+// PostgreSQL and the in-memory database, Memfile.
+// We'll use memfile  because it doesn't require any prior set up.
+// Note, we're setting the maximum number of row read errors to 100,
+// (defaults to 0, meaning unlimited).
+  "lease-database": {
+      "type": "memfile",
+      "lfc-interval": 3600,
+      "max-row-errors": 100
+  },
+
+// The following parameters control processing expired leases. Expired
+// leases will be reclaimed periodically according to the
+// "reclaim-timer-wait-time" parameter. Reclaimed leases will be held in
+// the database for 1800s to facilitate lease affinity. After this
+// period the leases will be removed.  The frequency of removal is
+// controlled by the "flush-reclaimed-timer-wait-time" parameter. The
+// lease reclamation routine will process at most 500 leases or will
+// last for at most 100ms, during a single run. If there are still some
+// unreclaimed leases after 10 attempts, a warning message is issued.
+  "expired-leases-processing": {
+    "reclaim-timer-wait-time": 5,
+    "hold-reclaimed-time": 1800,
+    "flush-reclaimed-timer-wait-time": 10,
+    "max-reclaim-leases": 500,
+    "max-reclaim-time": 100,
+    "unwarned-reclaim-cycles": 10
+  },
+
+// Addresses will be assigned with a lifetime of 4000 seconds.
+  "valid-lifetime": 4000,
+
+// The following list defines subnets. We have only one subnet
+// here. We tell Kea that it is directly available over local interface.
+  "subnet4": [
+    {
+       "pools": [ { "pool":  "192.0.2.1 - 192.0.2.200" } ],
+       "subnet": "192.0.2.0/24",
+       "interface": "eth0"
+    }
+  ],
+
+// The following configures logging. It assumes that messages with at
+// least informational level (info, warn, error and fatal) should be
+// logged to stdout.
+    "loggers": [
+        {
+            "name": "kea-dhcp4",
+            "output_options": [
+                {
+                    "output": "stdout"
+                }
+            ],
+            "severity": "INFO"
+        }
+    ]
+}
+
+}
diff --git a/doc/examples/kea4/multiple-options.json b/doc/examples/kea4/multiple-options.json
new file mode 100644
index 0000000..9498891
--- /dev/null
+++ b/doc/examples/kea4/multiple-options.json
@@ -0,0 +1,186 @@
+// This is an example configuration file for the DHCPv4 server in Kea.
+// It demonstrates simple configuration of the options for a subnet.
+
+{ "Dhcp4":
+
+{
+// Kea is told to listen on eth0 interface only.
+  "interfaces-config": {
+    "interfaces": [ "eth0" ]
+  },
+
+// We need to specify the database used to store leases. As of
+// June 2022, three database backends are supported: MySQL,
+// PostgreSQL and the in-memory database, Memfile.
+// We'll use memfile  because it doesn't require any prior set up.
+  "lease-database": {
+    "type": "memfile"
+  },
+
+// Addresses will be assigned with a lifetime of 4000 seconds.
+  "valid-lifetime": 4000,
+
+// Renew and rebind timers are commented out. This implies that options
+// 58 and 59 will not be sent to the client. In this case it is up to
+// the client to pick the timer values according to RFC2131. Uncomment the
+// timers to send these options to the client.
+//  "renew-timer": 1000,
+//  "rebind-timer": 2000,
+
+// Defining a subnet. There are some DHCP options returned to the
+// clients connected to this subnet. The first and third options are
+// clients connected to this subnet. The first two options are
+// identified by the name. The third option is identified by the
+// option code.
+// There is an address pool defined within this subnet. Pool
+// specific value for option domain-name-servers is defined
+// for the pool.
+  "subnet4": [
+    {
+       "subnet": "192.0.2.0/24",
+       "option-data": [
+            // When specifying options, you typically need to specify
+            // one of (name or code) and data. The full option specification
+            // covers name, code, space, csv-format and data.
+            // space defaults to "dhcp4" which is usually correct, unless you
+            // use encapsulate options. csv-format defaults to "true", so
+            // this is also correct, unless you want to specify the whole
+            // option value as long hex string. For example, to specify
+            // domain-name-servers you could do this:
+            // {
+            //     "name": "domain-name-servers",
+            //     "code": 6,
+            //     "csv-format": true,
+            //     "space": "dhcp4",
+            //     "data": "192.0.2.1, 192.0.2.2"
+            // }
+            // but it's a lot of writing, so it's easier to do this instead:
+         {
+             "name": "domain-name-servers",
+             "data": "192.0.2.1, 192.0.2.2"
+         },
+            // Note the Kea provides some of the options on its own. In
+            // particular:
+
+            // - IP address lease time (option 51) is governed by
+            //   valid-lifetime parameter, so you don't need to specify
+            //   it as option.
+            // - Subnet mask (option 1) is calculated automatically from the
+            //   subnet parameter specified for each "subnet4" entry.
+            // - renewal-timer (option 58) is calculated from renew-timer
+            //   parameter
+            // - rebind timer (option 59) is calculated from rebind-timer
+            //   parameter
+
+            // For each IPv4 subnet you most likely need to specify at least
+            // one router.
+         {
+             "name": "routers",
+             "data": "192.0.2.1"
+         },
+
+            // Typically people prefer to refer to options by their
+            // names, so they don't need to remember the code names.
+            // However, some people like to use numerical values. For
+            // example, option "domain-name" uses option code 15, so you
+            // can reference to it either by
+            // "name": "domain-name" or "code": 15.
+         {
+             "code": 15,
+             "data": "example.org"
+         },
+             // Domain search is also a popular option. It tells the client to
+             // attempt to resolve names within those specified domains. For
+             // example, name "foo" would be attempted to be resolved as
+             // foo.mydomain.example.com and if it fails, then as
+             // foo.example.com
+
+         {
+             "name": "domain-search",
+             "data": "mydomain.example.com, example.com"
+         },
+
+           // Options can also be specified using hexadecimal format.
+           // This should be avoided if possible, because Kea ability to
+           // validate correctness is limited when using hex values.
+         {
+             "name": "broadcast-address",
+             "csv-format": false,
+             "data": "ffff8000"
+         },
+
+            // String options that have a comma in their values need to have
+            // it escaped (i.e. each comma is preceded by two backslashes).
+            // That's because commas are reserved for separating fields in
+            // compound options. At the same time, we need to be conformant
+            // with JSON spec, that does not allow "\,". Therefore the
+            // slightly uncommon double backslashes notation is needed.
+
+            // Legal JSON escapes are \ followed by "\/bfnrt character
+            // or \u followed by 4 hexa-decimal numbers (currently Kea
+            // supports only \u0000 to \u00ff code points).
+            // CSV processing translates '\\' into '\' and '\,' into ','
+            // only so for instance '\x' is translated into '\x'. But
+            // as it works on a JSON string value each of these '\'
+            // characters must be doubled on JSON input.
+         {
+            "name": "boot-file-name",
+            "data": "EST5EDT4\\,M3.2.0/02:00\\,M11.1.0/02:00"
+
+         },
+            // Options that take integer values can either be specified in
+            // dec or hex format. Hex format could be either plain (e.g. abcd)
+            // or prefixed with 0x (e.g. 0xabcd).
+         {
+            "name": "default-ip-ttl",
+            "data": "0xf0"
+         },
+            // At a few exceptions options are added to response only when
+            // the client requests them. The always-send flag should be used
+            // to enforce a particular option.
+         {
+            "name": "vendor-class-identifier",
+            "data": "isc",
+            "always-send": true
+         }
+       ],
+
+        // Now we define pools. There are two pools here.
+        "pools": [ {
+            // This is the first pool. Nothing spectacular here, just a range
+            // of addresses.
+           "pool": "192.0.2.10 - 192.0.2.100"
+
+          }, {
+            // This second pool is more interesting. Anyone who gets an
+            // address from this pool will also get this specific option
+            // value if asks for DNS servers configuration. This value,
+            // being more specific, overrides any values that were specified
+            // on either global or subnet scope.
+            "pool":  "192.0.2.101 - 192.0.2.200",
+            "option-data": [
+                {
+                    "name": "domain-name-servers",
+                    "data": "192.0.2.3, 192.0.2.4"
+                }
+          ]
+        } ]
+    } ],
+
+// The following configures logging. It assumes that messages with at
+// least informational level (info, warn, error and fatal) should be
+// logged to stdout.
+    "loggers": [
+        {
+            "name": "kea-dhcp4",
+            "output_options": [
+                {
+                    "output": "stdout"
+                }
+            ],
+            "severity": "INFO"
+        }
+    ]
+}
+
+}
diff --git a/doc/examples/kea4/mysql-reservations.json b/doc/examples/kea4/mysql-reservations.json
new file mode 100644
index 0000000..5742985
--- /dev/null
+++ b/doc/examples/kea4/mysql-reservations.json
@@ -0,0 +1,103 @@
+// This is an example configuration file for the DHCPv4 server in Kea.
+// It contains configuration of the MySQL host database backend, used
+// to retrieve reserved addresses, host names, DHCPv4 message fields
+// and DHCP options from MySQL database.
+{ "Dhcp4":
+
+{
+// Kea is told to listen on eth0 interface only.
+  "interfaces-config": {
+    "interfaces": [ "eth0" ]
+
+  },
+
+// We need to specify the database used to store leases. As of
+// June 2022, three database backends are supported: MySQL,
+// PostgreSQL and the in-memory database, Memfile.
+// We'll use memfile  because it doesn't require any prior set up.
+  "lease-database": {
+      "type": "memfile",
+      "lfc-interval": 3600
+  },
+
+// Addresses will be assigned with a lifetime of 4000 seconds.
+  "valid-lifetime": 4000,
+
+// Renew and rebind timers are commented out. This implies that options
+// 58 and 59 will not be sent to the client. In this case it is up to
+// the client to pick the timer values according to RFC2131. Uncomment the
+// timers to send these options to the client.
+//  "renew-timer": 1000,
+//  "rebind-timer": 2000,
+
+
+// Kea supports reservations by several different types of
+// identifiers: hw-address (hardware/MAC address of the client), duid
+// (DUID inserted by the client), client-id (client identifier inserted
+// by the client) and circuit-id (circuit identifier inserted by the
+// relay agent). When told to do so, Kea can check for all of those
+// identifier types, but it takes a costly database lookup to do so. It
+// is therefore useful from a performance perspective to use only the
+// reservation types that are actually used in a given network.
+
+// The example below is not optimal from a performance perspective, but it
+// nicely showcases the host reservation capabilities. Please use the minimum
+// set of identifier types used in your network.
+  "host-reservation-identifiers":
+    [ "circuit-id", "hw-address", "duid", "client-id" ],
+
+// Specify connection to the database holding host reservations. The type
+// specifies that the MySQL database is used. user and password are the
+// credentials used to connect to the database. host and name specify
+// location of the host where the database instance is running, and the
+// name of the database to use. The server processing a packet will first
+// check if there are any reservations specified for this client in the
+// reservations list, within the subnet (configuration file). If there are
+// no reservations there, the server will try to retrieve reservations
+// from this database.
+  "hosts-database": {
+    "type": "mysql",
+    "reconnect-wait-time": 3000, // expressed in ms
+    "max-reconnect-tries": 3,
+    "name": "keatest",
+    "user": "keatest",
+    "password": "keatest",
+    "host": "localhost",
+    "port": 3306,
+    "trust-anchor": "my-ca",
+    "cert-file": "my-cert",
+    "key-file": "my-key",
+    "cipher-list": "AES"
+  },
+
+// Define a subnet with a single pool of dynamic addresses. Addresses from
+// this pool will be assigned to clients which don't have reservations in the
+// database. Subnet identifier is equal to 1. If this subnet is selected for
+// the client, this subnet id will be used to search for the reservations
+// within the database.
+  "subnet4": [
+    {
+       "pools": [ { "pool":  "192.0.2.10 - 192.0.2.200" } ],
+       "subnet": "192.0.2.0/24",
+       "interface": "eth0",
+       "id": 1
+    }
+  ],
+
+// The following configures logging. It assumes that messages with at
+// least informational level (info, warn, error and fatal) should be
+// logged to stdout.
+    "loggers": [
+        {
+            "name": "kea-dhcp4",
+            "output_options": [
+                {
+                    "output": "stdout"
+                }
+            ],
+            "severity": "INFO"
+        }
+    ]
+}
+
+}
diff --git a/doc/examples/kea4/pgsql-reservations.json b/doc/examples/kea4/pgsql-reservations.json
new file mode 100644
index 0000000..9f6d301
--- /dev/null
+++ b/doc/examples/kea4/pgsql-reservations.json
@@ -0,0 +1,101 @@
+// This is an example configuration file for the DHCPv4 server in Kea.
+// It contains configuration of the PostgreSQL host database backend, used
+// to retrieve reserved addresses, host names, DHCPv4 message fields
+// and DHCP options from PostgreSQL database.
+{ "Dhcp4":
+
+{
+// Kea is told to listen on eth0 interface only.
+  "interfaces-config": {
+    "interfaces": [ "eth0" ]
+  },
+
+
+// We need to specify the database used to store leases. As of
+// June 2022, three database backends are supported: MySQL,
+// PostgreSQL and the in-memory database, Memfile.
+// We'll use memfile  because it doesn't require any prior set up.
+  "lease-database": {
+    "type": "memfile"
+  },
+
+// Addresses will be assigned with a lifetime of 4000 seconds.
+  "valid-lifetime": 4000,
+
+// Renew and rebind timers are commented out. This implies that options
+// 58 and 59 will not be sent to the client. In this case it is up to
+// the client to pick the timer values according to RFC2131. Uncomment the
+// timers to send these options to the client.
+//  "renew-timer": 1000,
+//  "rebind-timer": 2000,
+
+
+// Kea supports reservations by several different types of
+// identifiers: hw-address (hardware/MAC address of the client), duid
+// (DUID inserted by the client), client-id (client identifier inserted
+// by the client) and circuit-id (circuit identifier inserted by the
+// relay agent). When told to do so, Kea can check for all of those
+// identifier types, but it takes a costly database lookup to do so. It
+// is therefore useful from a performance perspective to use only the
+// reservation types that are actually used in a given network.
+
+// The example below is not optimal from a performance perspective, but it
+// nicely showcases the host reservation capabilities. Please use the minimum
+// set of identifier types used in your network.
+  "host-reservation-identifiers":
+    [ "circuit-id", "hw-address", "duid", "client-id" ],
+
+// Specify connection to the database holding host reservations. The type
+// specifies that the PostgreSQL database is used. user and password are the
+// credentials used to connect to the database. host and name specify
+// location of the host where the database instance is running, and the
+// name of the database to use. The server processing a packet will first
+// check if there are any reservations specified for this client in the
+// reservations list, within the subnet (configuration file). If there are
+// no reservations there, the server will try to retrieve reservations
+// from this database.
+// The database specification can go into one hosts-database entry for
+// backward compatibility or be listed in hosts-databases list.
+  "hosts-databases": [
+    {
+       "type": "postgresql",
+       "reconnect-wait-time": 3000, // expressed in ms
+       "max-reconnect-tries": 3,
+       "name": "keatest",
+       "user": "keatest",
+       "password": "keatest",
+       "host": "localhost"
+    }
+  ],
+
+// Define a subnet with a single pool of dynamic addresses. Addresses from
+// this pool will be assigned to clients which don't have reservations in the
+// database. Subnet identifier is equal to 1. If this subnet is selected for
+// the client, this subnet id will be used to search for the reservations
+// within the database.
+  "subnet4": [
+    {
+       "pools": [ { "pool":  "192.0.2.10 - 192.0.2.200" } ],
+       "subnet": "192.0.2.0/24",
+       "interface": "eth0",
+       "id": 1
+    }
+  ],
+
+// The following configures logging. It assumes that messages with at
+// least informational level (info, warn, error and fatal) should be
+// logged to stdout.
+    "loggers": [
+        {
+            "name": "kea-dhcp4",
+            "output_options": [
+                {
+                    "output": "stdout"
+                }
+            ],
+            "severity": "INFO"
+        }
+    ]
+}
+
+}
diff --git a/doc/examples/kea4/reservations.json b/doc/examples/kea4/reservations.json
new file mode 100644
index 0000000..c00a8e9
--- /dev/null
+++ b/doc/examples/kea4/reservations.json
@@ -0,0 +1,182 @@
+// This is an example configuration file for the DHCPv4 server in Kea.
+// It contains one subnet in which there are two static address reservations
+// for the clients identified by the MAC addresses.
+{ "Dhcp4":
+
+{
+// Kea is told to listen on eth0 interface only.
+  "interfaces-config": {
+    "interfaces": [ "eth0" ]
+  },
+
+// We need to specify the database used to store leases. As of April
+// 2022, three database backends are supported: MySQL, PostgreSQL, and the
+// in-memory database, Memfile.  We'll use memfile because it doesn't
+// require any prior set up.
+  "lease-database": {
+      "type": "memfile",
+      "lfc-interval": 3600
+  },
+
+// Addresses will be assigned with a lifetime of 4000 seconds.
+  "valid-lifetime": 4000,
+
+// Renew and rebind timers are commented out. This implies that options
+// 58 and 59 will not be sent to the client. In this case it is up to
+// the client to pick the timer values according to RFC2131. Uncomment the
+// timers to send these options to the client.
+//  "renew-timer": 1000,
+//  "rebind-timer": 2000,
+
+// Kea supports reservations by several different types of identifiers:
+// hw-address (hardware/MAC address of the client), duid (DUID inserted by the
+// client), client-id (client identifier inserted by the client), circuit-id
+// (circuit identifier inserted by the relay agent) and flex-id (flexible
+// identifier available when flex_id hook library is loaded). When told to do
+// so, Kea can check for all of those identifier types, but it takes a costly
+// database lookup to do so. It is therefore useful from a performance
+// perspective to use only the reservation types that are actually used in a
+// given network.
+
+// The example below is not optimal from a performance perspective, but it
+// nicely showcases the host reservation capabilities. Please use the minimum
+// set of identifier types used in your network.
+"host-reservation-identifiers": [ "circuit-id", "hw-address", "duid",
+                                  "client-id", "flex-id" ],
+
+// Define a subnet with four reservations. Some of the reservations belong
+// to the dynamic pool. Kea is able to handle this case, but it is not
+// recommended from a performance perspective, as Kea would not only need to
+// check if a given address is free, but also whether it is reserved.
+// To avoid this check, one can change reservation-mode to out-of-pool, rather
+// than 'all'. If a subnet does not have reservations at all, the reservation
+// lookup can be skipped altogether (reservation-mode is set to 'disabled').
+// The reservation-mode has been replaced by reservations-global,
+// reservations-in-subnet and reservations-out-of-pool.
+
+// Note that the second reservation is for an address which is within the
+// range of the pool of the dynamically allocated address. The server will
+// exclude this address from this pool and only assign it to the client which
+// has a reservation for it.
+  "subnet4": [
+    {
+        "pools": [ { "pool":  "192.0.2.1 - 192.0.2.200" } ],
+        "subnet": "192.0.2.0/24",
+        "interface": "eth0",
+        // This directive tells Kea that reservations may be made both in-pool
+        // and out-of-pool. For improved performance, you may move all reservations
+        // out of the dynamic pool and change reservation-mode to "out-of-pool".
+        // Kea will then be able to skip querying for host reservations when
+        // assigning leases from dynamic pool.
+        // "reservation-mode": "all",
+        // It is replaced by the "reservations-global", "reservations-in-subnet"
+        // and "reservations-out-of-pool" parameters.
+
+        // Specify if server should lookup global reservations.
+        "reservations-global": false,
+
+        // Specify if server should lookup in-subnet reservations.
+        "reservations-in-subnet": true,
+
+        // Specify if server can assume that all reserved addresses
+        // are out-of-pool.
+        // Ignored when reservations-in-subnet is false.
+        // If specified, it is inherited by "shared-networks" and
+        // "subnet4" levels.
+        "reservations-out-of-pool": false,
+
+        "reservations": [
+
+// This is a reservation for a specific hardware/MAC address. It's a very
+// simple reservation: just an address and nothing else.
+        {
+            "hw-address": "1a:1b:1c:1d:1e:1f",
+            "ip-address": "192.0.2.201"
+        },
+
+// This is a reservation for a specific client-id. It also shows
+// the this client will get a reserved hostname. A hostname can be defined
+// for any identifier type, not just client-id.
+        {
+            "client-id": "01:11:22:33:44:55:66",
+            "ip-address": "192.0.2.202",
+            "hostname": "special-snowflake"
+        },
+
+// The third reservation is based on DUID. This reservation also
+// defines special option values for this particular client. If
+// the domain-name-servers option would have been defined on a global,
+// subnet or class level, the host specific values take preference.
+        {
+            "duid": "01:02:03:04:05",
+            "ip-address": "192.0.2.203",
+            "option-data": [ {
+                "name": "domain-name-servers",
+                "data": "10.1.1.202,10.1.1.203"
+            } ]
+        },
+
+// The fourth reservation is based on circuit-id. This is an option inserted
+// by the relay agent that forwards the packet from client to the server.
+// In this example the host is also assigned vendor specific options.
+        {
+            "circuit-id": "01:11:22:33:44:55:66",
+            "ip-address": "192.0.2.204",
+            "option-data": [
+                {
+                    "name": "vivso-suboptions",
+                    "data": "4491"
+                },
+                {
+                    "name": "tftp-servers",
+                    "space": "vendor-4491",
+                    "data": "10.1.1.202,10.1.1.203"
+                }
+            ]
+        },
+// This reservation is for a client that needs specific DHCPv4 fields to be
+// set. Three supported fields are next-server, server-hostname and
+// boot-file-name
+        {
+            "client-id": "01:0a:0b:0c:0d:0e:0f",
+            "ip-address": "192.0.2.205",
+            "next-server": "192.0.2.1",
+            "server-hostname": "hal9000",
+            "boot-file-name": "/dev/null"
+        },
+
+// This reservation is using flexible identifier. Instead of relying
+// on specific field, sysadmin can define an expression similar to what
+// is used for client classification,
+// e.g. substring(relay[0].option[17],0,6). Then, based on the value of
+// that expression for incoming packet, the reservation is matched.
+// Expression can be specified either as hex or plain text using single
+// quotes.
+// Note: flexible identifier requires flex_id hook library to be
+// loaded to work.
+        {
+            "flex-id": "'s0mEVaLue'",
+            "ip-address": "192.0.2.206"
+        }
+
+      ]
+    }
+  ],
+
+// The following configures logging. It assumes that messages with at
+// least informational level (info, warn, error and fatal) should be
+// logged to stdout.
+    "loggers": [
+        {
+            "name": "kea-dhcp4",
+            "output_options": [
+                {
+                    "output": "stdout"
+                }
+            ],
+            "severity": "INFO"
+        }
+    ]
+}
+
+}
diff --git a/doc/examples/kea4/several-subnets.json b/doc/examples/kea4/several-subnets.json
new file mode 100644
index 0000000..5fb0511
--- /dev/null
+++ b/doc/examples/kea4/several-subnets.json
@@ -0,0 +1,83 @@
+// This is an example configuration file for DHCPv4 server in Kea.
+// It's a basic scenario with three IPv4 subnets configured. In each
+// subnet, there's a smaller pool of dynamic addresses.
+
+{ "Dhcp4":
+
+{
+// Kea is told to listen on eth0 interface only.
+  "interfaces-config": {
+    "interfaces": [ "eth0" ]
+  },
+
+// We need to specify the database used to store leases. As of
+// June 2022, three database backends are supported: MySQL,
+// PostgreSQL and the in-memory database, Memfile.
+// We'll use memfile  because it doesn't require any prior set up.
+  "lease-database": {
+    "type": "memfile"
+  },
+
+// Addresses will be assigned with a lifetime of 4000 seconds.
+// The client is told to start renewing after 1000 seconds. If the server
+// does not respond within 2000 seconds of the lease being granted, client
+// is supposed to start REBIND procedure (emergency renewal that allows
+// switching to a different server).
+  "valid-lifetime": 4000,
+  "renew-timer": 1000,
+  "rebind-timer": 2000,
+
+// RFC6842 says that the server is supposed to echo back client-id option.
+// However, some older clients do not support this and are getting confused
+// when they get their own client-id. Kea can disable RFC6842 support.
+  "echo-client-id": false,
+
+// Some clients don't use stable client identifier, but rather generate them
+// during each boot. This may cause a client that reboots frequently to get
+// multiple leases, which may not be desirable. As such, sometimes admins
+// prefer to tell their DHCPv4 server to ignore client-id value altogether
+// and rely exclusively on MAC address. This is a parameter that is defined
+// globally, but can be overridden on a subnet level.
+  "match-client-id": true,
+
+  // By default, Kea ignores requests by clients for unknown IP addresses,
+  // because other non-cooperating DHCP servers could reside on the same
+  // network (RFC 2131). This parameter is defined globally, but can be
+  // overridden on a subnet level
+  "authoritative": false,
+
+// The following list defines subnets. Each subnet consists of at
+// least subnet and pool entries.
+  "subnet4": [
+  {
+      "pools": [ { "pool":  "192.0.2.1 - 192.0.2.200" } ],
+      "subnet": "192.0.2.0/24"
+  },
+  {
+// This particular subnet has match-client-id value changed.
+      "pools": [ { "pool": "192.0.3.100 - 192.0.3.200" } ],
+      "subnet": "192.0.3.0/24",
+      "match-client-id": false
+  },
+  {
+      "pools": [ { "pool": "192.0.4.1 - 192.0.4.254" } ],
+      "subnet": "192.0.4.0/24"
+  } ],
+
+// The following configures logging. It assumes that messages with at
+// least informational level (info, warn, error and fatal) should be
+// logged to stdout.
+    "loggers": [
+        {
+            "name": "kea-dhcp4",
+            "output_options": [
+                {
+                    "output": "stdout"
+                }
+            ],
+            "severity": "INFO"
+        }
+    ]
+}
+
+}
diff --git a/doc/examples/kea4/shared-network.json b/doc/examples/kea4/shared-network.json
new file mode 100644
index 0000000..9f38ee8
--- /dev/null
+++ b/doc/examples/kea4/shared-network.json
@@ -0,0 +1,164 @@
+// This is an example configuration file for DHCPv4 server in Kea.
+// It demonstrates an advanced feature called shared network. Typically, for
+// each physical link there is one IPv4 subnet that the server is expected
+// to manage. However, in some cases there is a need to configure more subnets
+// in the same physical location. The most common use case is an existing
+// subnet that grew past its original assumptions and ran out of addresses,
+// so the sysadmin needs to add another subnet on top of existing one.
+{
+    "Dhcp4": {
+
+        // As with any other configuration, you need to tell Kea the interface
+        // names, so it would listen to incoming traffic.
+        "interfaces-config": {
+            "interfaces": [ "eth0" ]
+        },
+
+        // You also need to tell where to store lease information.
+        // memfile is the backend that is easiest to set up.
+        "lease-database": {
+            "type": "memfile",
+            "lfc-interval": 3600
+        },
+
+        // The shared networks definition starts here. shared-networks can
+        // contain a list of shared networks. There are many parameters
+        // that can be specified here, so this example may be overwhelming
+        // at first, but the only mandatory parameter for each shared
+        // network is name. It must be unique. Typically, each shared
+        // network also needs to have at least two subnets to be functional,
+        // but if you really want to, you can define a degraded shared
+        // network that has 1 or even 0 subnets. This may come in handy
+        // when migrating between regular subnets and shared networks
+        // or when debugging a problem. It is not recommended to use
+        // 1 subnet per shared network, as there is extra processing
+        // overhead for shared networks.
+        "shared-networks": [
+        {
+            // Name of the shared network. It may be an arbitrary string
+            // and it must be unique among all shared networks.
+            "name": "frog",
+
+            // You may specify interface name if the shared network is
+            // reachable directly from the server.
+            "interface": "eth1",
+
+            // You can specify many parameters that are allowed in subnet scope
+            // here. It's useful to put them here if they apply to all subnets
+            // in this shared network. It's likely that the most common
+            // parameter here will be option values defined with option-data.
+            "match-client-id": false,
+            "option-data": [ ],
+            "rebind-timer": 150,
+            "authoritative": true,
+
+            // If all the traffic coming from that shared network is reachable
+            // via relay and that relay always use the same IP address, you
+            // can specify that relay address here. Since this example shows
+            // a shared network reachable directly, we put 0.0.0.0 here.
+            // It would be better to skip the relay scope altogether, but
+            // it was left here for demonstration purposes.
+            "relay": {
+                "ip-address": "0.0.0.0"
+            },
+
+            // Timer values can be overridden here.
+            "renew-timer": 100,
+
+            // "reservation-mode": "all",
+            // It is replaced by the "reservations-global",
+            // "reservations-in-subnet" and "reservations-out-of-pool"
+            // parameters.
+
+            // Specify if server should lookup global reservations.
+            "reservations-global": false,
+
+            // Specify if server should lookup in-subnet reservations.
+            "reservations-in-subnet": true,
+
+            // Specify if server can assume that all reserved addresses
+            // are out-of-pool.
+            // Ignored when reservations-in-subnet is false.
+            // If specified, it is inherited by "subnet4" levels.
+            "reservations-out-of-pool": false,
+
+            // This starts a list of subnets allowed in this shared network.
+            // In our example, there are two subnets.
+            "subnet4": [
+                {
+                    "id": 1,
+                    "match-client-id": true,
+                    "next-server": "0.0.0.0",
+                    "server-hostname": "",
+                    "boot-file-name": "",
+                    "option-data": [ ],
+                    "pools": [ ],
+                    "rebind-timer": 20,
+
+                    // You can override the value inherited from shared-network
+                    // here if your relay uses different IP addresses for
+                    // each subnet.
+                    "relay": {
+                        "ip-address": "0.0.0.0"
+                    },
+                    "renew-timer": 10,
+                    // "reservation-mode": "all",
+                    // It is replaced by the "reservations-global",
+                    // "reservations-in-subnet" and "reservations-out-of-pool"
+                    // parameters.
+                    // Specify if server should lookup global reservations.
+                    "reservations-global": false,
+                    // Specify if server should lookup in-subnet reservations.
+                    "reservations-in-subnet": true,
+                    // Specify if server can assume that all reserved addresses
+                    // are out-of-pool.
+                    // Ignored when reservations-in-subnet is false.
+                    "reservations-out-of-pool": false,
+                    "subnet": "10.0.0.0/8",
+                    "valid-lifetime": 30
+                },
+                {
+                    "id": 2,
+                    "match-client-id": true,
+                    "next-server": "0.0.0.0",
+                    "server-hostname": "",
+                    "boot-file-name": "",
+                    "option-data": [ ],
+                    "pools": [ ],
+                    "rebind-timer": 20,
+                    "renew-timer": 10,
+                    // "reservation-mode": "all",
+                    // It is replaced by the "reservations-global",
+                    // "reservations-in-subnet" and "reservations-out-of-pool"
+                    // parameters.
+                    // Specify if server should lookup global reservations.
+                    "reservations-global": false,
+                    // Specify if server should lookup in-subnet reservations.
+                    "reservations-in-subnet": true,
+                    // Specify if server can assume that all reserved addresses
+                    // are out-of-pool.
+                    // Ignored when reservations-in-subnet is false.
+                    "reservations-out-of-pool": false,
+                    "subnet": "192.0.2.0/24",
+                    "valid-lifetime": 30
+                }
+            ],
+            "valid-lifetime": 200
+        } ], // end of shared-networks
+
+        // It is likely that in your network you'll have a mix of regular,
+        // "plain" subnets and shared networks. It is perfectly valid to mix
+        // them in the same config file.
+        //
+        // This is regular subnet. It's not part of any shared-network.
+        "subnet4": [
+            {
+                "pools": [ { "pool":  "192.0.3.1 - 192.0.3.200" } ],
+                "subnet": "192.0.3.0/24",
+                "interface": "eth0",
+                "id": 3
+            }
+        ]
+
+    } // end of Dhcp4
+}
diff --git a/doc/examples/kea4/single-subnet.json b/doc/examples/kea4/single-subnet.json
new file mode 100644
index 0000000..3fa6dfb
--- /dev/null
+++ b/doc/examples/kea4/single-subnet.json
@@ -0,0 +1,59 @@
+// This is an example configuration file for the DHCPv4 server in Kea.
+// It is a basic scenario with one IPv4 subnet configured. The subnet
+// contains a single pool of dynamically allocated addresses.
+
+{ "Dhcp4":
+
+{
+// Kea is told to listen on eth0 interface only.
+  "interfaces-config": {
+    "interfaces": [ "eth0" ]
+  },
+
+// We need to specify the database used to store leases. As of
+// June 2022, three database backends are supported: MySQL,
+// PostgreSQL and the in-memory database, Memfile.
+// We'll use memfile  because it doesn't require any prior set up.
+  "lease-database": {
+      "type": "memfile",
+      "lfc-interval": 3600
+  },
+
+// Addresses will be assigned with a lifetime of 4000 seconds.
+  "valid-lifetime": 4000,
+
+// Renew and rebind timers are commented out. This implies that options
+// 58 and 59 will not be sent to the client. In this case it is up to
+// the client to pick the timer values according to RFC2131. Uncomment the
+// timers to send these options to the client.
+//  "renew-timer": 1000,
+//  "rebind-timer": 2000,
+
+// The following list defines subnets. We have only one subnet
+// here. We tell Kea that it is directly available over local interface.
+  "subnet4": [
+    {
+       "pools": [ { "pool":  "192.0.2.1 - 192.0.2.200" } ],
+       "subnet": "192.0.2.0/24",
+       "interface": "eth0"
+    }
+  ],
+
+// The following configures logging. It assumes that messages with at
+// least informational level (info, warn, error and fatal) should be
+// logged to stdout. Alternatively, you can specify stderr here, a filename
+// or 'syslog', which will store output messages via syslog.
+    "loggers": [
+        {
+            "name": "kea-dhcp4",
+            "output_options": [
+                {
+                    "output": "stdout"
+                }
+            ],
+            "severity": "INFO"
+        }
+    ]
+}
+
+}
diff --git a/doc/examples/kea4/vendor-specific.json b/doc/examples/kea4/vendor-specific.json
new file mode 100644
index 0000000..431c04e
--- /dev/null
+++ b/doc/examples/kea4/vendor-specific.json
@@ -0,0 +1,95 @@
+// This is an example configuration file for the DHCPv4 server in Kea.
+// The purpose of this example is to showcase how configure
+// Vendor Specific Information (code 43) RFC 2132 section 8.4
+{
+    "Dhcp4": {
+        "option-def": [
+            {
+// Two options that we are planning to include in option 43 as suboptions
+// should be defined on global level
+                "array": false,
+                "code": 2,
+                "name": "vlanid",
+// suboptions should have space configured and it can't start with 'vendor-'
+// otherwise those will be included in 125 option not 43
+                "space": "339",
+                "type": "uint32"
+            },
+            {
+                "array": false,
+                "code": 3,
+                "name": "dls",
+                "space": "339",
+                "type": "string"
+            }
+        ],
+        "client-classes": [
+            {
+
+// Kea needs classification based on option 60, you can either use name:
+// VENDOR_CLASS_ + option 60 content (test parameter is not required than)
+// or use any name and add "test" parameter accordingly e.g.
+// "test": "substring(option[60].hex,0,9) == 'partial-content-of-option-60'"
+                "name": "VENDOR_CLASS_339",
+                "option-def": [
+                    {
+// Vendor-specific option has to be defined on the class level, if we're planning
+// to send a single value, then define its type accordingly. If this option
+// should encapsulate other suboptions, the "space" parameter should be the same
+// as included suboptions and "type" set to empty
+                        "code": 43,
+// Using the "encapsulate" direction, Kea is told to include options from
+// the "339" namespace. We have defined several such options earlier.
+// This way, the sub-options are "glued" to this option 43.
+                        "encapsulate": "339",
+                        "name": "vendor-encapsulated-options",
+                        "type": "empty"
+                    }
+                ],
+                "option-data": [
+                    {
+// vendor-encapsulated-options and defined option on global level should
+// be also configured  with proper "data" parameters in "option-data" list.
+// Because Kea will send only option that client ask for, and there is no way
+// to ask for suboptions, parameter "always-send" with value set
+// to true has also be included in all custom suboptions
+                        "name": "vendor-encapsulated-options"
+                    },
+                    {
+                        "always-send": true,
+                        "data": "123",
+                        "name": "vlanid",
+                        "space": "339"
+                    },
+                    {
+                        "always-send": true,
+                        "data": "sdlp://192.0.2.11:18443",
+                        "name": "dls",
+                        "space": "339"
+                    }
+                ]
+            }
+        ],
+// Kea is told to listen on eth0 interface only.
+        "interfaces-config": {
+            "interfaces": ["eth0"]
+        },
+// We need to specify the database used to store leases.
+        "lease-database": {
+            "type": "memfile"
+        },
+// The following list defines subnets. We have only one subnet
+// here. We tell Kea that it is directly available over local interface.
+        "subnet4": [
+            {
+                "interface": "eth0",
+                "pools": [
+                    {
+                        "pool": "192.0.2.50-192.0.2.50"
+                    }
+                ],
+                "subnet": "192.0.2.0/24"
+            }
+        ]
+    }
+}
diff --git a/doc/examples/kea4/vivso.json b/doc/examples/kea4/vivso.json
new file mode 100644
index 0000000..fe1ccec
--- /dev/null
+++ b/doc/examples/kea4/vivso.json
@@ -0,0 +1,89 @@
+// This is an example configuration file for the DHCPv4 server in Kea.
+// The purpose of this example is to showcase how configure
+// Vendor-Identifying Vendor-specific Information option
+// (code 125) RFC 3925
+
+
+{
+    "Dhcp4": {
+// If we want to send suboptions in option 125 first those have to be defined
+// on global level
+        "option-def": [
+            {
+                "array": false,
+                "code": 2,
+                "name": "vlanid",
+// In case of suboption of option 125 space has to start with prefix "vendor-"
+// in this case it's "vendor-" + vendor id from option 60 sent by client
+// 339 is Siemens Industry Inc.
+                "space": "vendor-339",
+                "type": "uint32"
+            },
+            {
+                "array": false,
+                "code": 3,
+                "name": "dls",
+                "space": "vendor-339",
+                "type": "string"
+            }
+        ],
+        "client-classes": [
+            {
+// Kea needs classification based on option 60, you can either use name:
+// VENDOR_CLASS_ + option 60 content (test parameter is not required than)
+// or use any name and add "test" parameter accordingly e.g.
+// "test": "substring(option[60].hex,0,9) == 'partial-content-of-option-60'"
+                "name": "VENDOR_CLASS_339",
+                "option-data": [
+                    {
+// In "option-data" list we have to configure option 125 with data parameter equal
+// to vendor-id we are expecting, also it will tell Kea which vendor space
+// encapsulate in suboptions.
+                        "data": "339",
+                        "name": "vivso-suboptions"
+                    },
+                    {
+// And additionally we have to configure all previously defined suboptions
+// with "space" parameter same as in option-def.
+// Because Kea will send only option that client ask for, and there is no way
+// to ask for suboptions parameter "always-send" with value set
+// to true has also be included in all custom suboptions.
+                        "always-send": true,
+                        "data": "123",
+                        "name": "vlanid",
+                        "space": "vendor-339"
+                    },
+                    {
+                        "always-send": true,
+                        "data": "sdlp://192.0.2.11:18443",
+                        "name": "dls",
+                        "space": "vendor-339"
+                    }
+                ]
+            }
+        ],
+// Kea is told to listen on eth0 interface only.
+        "interfaces-config": {
+            "interfaces": [
+                "eth0"
+            ]
+        },
+// We need to specify the database used to store leases.
+        "lease-database": {
+            "type": "memfile"
+        },
+// The following list defines subnets. We have only one subnet
+// here. We tell Kea that it is directly available over local interface.
+        "subnet4": [
+            {
+                "interface": "eth0",
+                "pools": [
+                    {
+                        "pool": "192.0.2.50-192.0.2.50"
+                    }
+                ],
+                "subnet": "192.0.2.0/24"
+            }
+        ]
+    }
+}
diff --git a/doc/examples/kea4/with-ddns.json b/doc/examples/kea4/with-ddns.json
new file mode 100644
index 0000000..ee47c62
--- /dev/null
+++ b/doc/examples/kea4/with-ddns.json
@@ -0,0 +1,83 @@
+// This is an example configuration file for the DHCPv4 server in Kea.
+// It is a basic scenario with one IPv4 subnet configured and with DDNS
+// enabled.
+
+{ "Dhcp4":
+
+{
+// Kea is told to listen on eth0 interface only.
+  "interfaces-config": {
+    "interfaces": [ "eth0" ]
+  },
+
+// We need to specify the database used to store leases. As of
+// June 2022, three database backends are supported: MySQL,
+// PostgreSQL and the in-memory database, Memfile.
+// We'll use memfile  because it doesn't require any prior set up.
+  "lease-database": {
+      "type": "memfile",
+      "lfc-interval": 3600
+  },
+
+// Addresses will be assigned with a lifetime of 4000 seconds.
+  "valid-lifetime": 4000,
+
+// Renew and rebind timers are commented out. This implies that options
+// 58 and 59 will not be sent to the client. In this case it is up to
+// the client to pick the timer values according to RFC2131. Uncomment the
+// timers to send these options to the client.
+//  "renew-timer": 1000,
+//  "rebind-timer": 2000,
+
+// The following list defines subnets. We have only one subnet
+// here. We tell Kea that it is directly available over local interface.
+  "subnet4": [
+    {
+       "pools": [ { "pool":  "192.0.2.1 - 192.0.2.200" } ],
+       "subnet": "192.0.2.0/24",
+       "interface": "eth0"
+    }
+  ],
+
+// Enable connectivity with kea-dhcp-ddns
+// (Required for dynamic DNS updates)
+  "dhcp-ddns" : {
+        "enable-updates" : true,
+        "server-ip" : "192.0.2.0",
+        "server-port" : 3432,
+        "sender-ip" : "192.0.2.1",
+        "sender-port" : 3433,
+        "max-queue-size" : 2048,
+        "ncr-protocol" : "UDP",
+        "ncr-format" : "JSON"
+   },
+
+// Enable DDNS updates and configure DDNS update behavior
+  "ddns-send-updates" : true,
+  "ddns-override-no-update" : true,
+  "ddns-override-client-update" : true,
+  "ddns-replace-client-name" : "when-present",
+  "ddns-generated-prefix" : "test.prefix",
+  "ddns-qualifying-suffix" : "test.suffix.",
+  "ddns-update-on-renew" : false,
+  "ddns-use-conflict-resolution" : true,
+  "hostname-char-set": "[^A-Za-z0-9.-]",
+  "hostname-char-replacement": "x",
+
+// The following configures logging. It assumes that messages with at
+// least informational level (info, warn, error and fatal) should be
+// logged to stdout.
+    "loggers": [
+        {
+            "name": "kea-dhcp4",
+            "output_options": [
+                {
+                    "output": "stdout"
+                }
+            ],
+            "severity": "INFO"
+        }
+    ]
+}
+
+}