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Merge pull request #1561 from abukharov/feature/dhcp-ddns
dhcp-server: ddns: T6773: DDNS configuration documentation
This commit is contained in:
Daniil Baturin
GitHub
commit
0858fe7233
@ -49,15 +49,15 @@ Configuration
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Inform client that the DNS server can be found at `<address>`.
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This is the configuration parameter for the entire shared network definition.
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All subnets will inherit this configuration item if not specified locally.
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All subnets will inherit this configuration item if not specified locally.
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Multiple DNS servers can be defined.
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.. cfgcmd:: set service dhcp-server shared-network-name <name> option
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.. cfgcmd:: set service dhcp-server shared-network-name <name> option
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vendor-option <option-name>
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This configuration parameter lets you specify a vendor-option for the
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entire shared network definition. All subnets will inherit this
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configuration item if not specified locally. An example for Ubiquiti is
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This configuration parameter lets you specify a vendor-option for the
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entire shared network definition. All subnets will inherit this
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configuration item if not specified locally. An example for Ubiquiti is
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shown below:
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**Example:**
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@ -66,14 +66,14 @@ Pass address of Unifi controller at ``172.16.100.1`` to all clients of ``NET1``
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.. code-block:: none
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set service dhcp-server shared-network-name 'NET1' option vendor-option
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set service dhcp-server shared-network-name 'NET1' option vendor-option
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ubiquiti '172.16.100.1'
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.. cfgcmd:: set service dhcp-server listen-address <address>
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This configuration parameter lets the DHCP server to listen for DHCP
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requests sent to the specified address, it is only realistically useful for
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a server whose only clients are reached via unicasts, such as via DHCP relay
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This configuration parameter lets the DHCP server to listen for DHCP
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requests sent to the specified address, it is only realistically useful for
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a server whose only clients are reached via unicasts, such as via DHCP relay
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agents.
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Individual Client Subnet
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@ -148,24 +148,205 @@ Individual Client Subnet
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request where no full FQDN is passed. This option can be given multiple times
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if you need multiple search domains (DHCP Option 119).
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.. cfgcmd:: set service dhcp-server shared-network-name <name> subnet <subnet>
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.. cfgcmd:: set service dhcp-server shared-network-name <name> subnet <subnet>
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option vendor-option <option-name>
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This configuration parameter lets you specify a vendor-option for the
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subnet specified within the shared network definition. An example for
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subnet specified within the shared network definition. An example for
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Ubiquiti is shown below:
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**Example:**
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Create ``172.18.201.0/24`` as a subnet within ``NET1`` and pass address of
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Create ``172.18.201.0/24`` as a subnet within ``NET1`` and pass address of
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Unifi controller at ``172.16.100.1`` to clients of that subnet.
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.. code-block:: none
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set service dhcp-server shared-network-name 'NET1' subnet
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set service dhcp-server shared-network-name 'NET1' subnet
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'172.18.201.0/24' option vendor-option ubiquiti '172.16.100.1'
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Dynamic DNS Update (RFC 2136)
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-----------------------------
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VyOS DHCP service supports RFC-2136 DDNS protocol. Based on DHCP lease change
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events, DHCP server generates DDNS update requests (defines as NameChangeRequests
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or NCRs) and posts them to a compliant DNS server, that will update its name
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database accordingly.
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VyOS built-in DNS Forwarder does not support DDNS, you will need an external DNS
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server with RFC-2136 DDNS support.
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.. cfgcmd:: set service dhcp-server dynamic-dns-update
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Enables DDNS globally.
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**Behavioral settings**
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These settings can be configured on the global level and overridden on the scope
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level, i.e. for individual shared networks or subnets. See examples below.
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.. cfgcmd:: set service dhcp-server dynamic-dns-update send-updates [ enable
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| disable ]
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If set to ``enable`` on global level, updates for all scopes will be enabled,
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except if explicitly set to ``disable`` on the scope level. If set to ``disable``,
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updates will only be sent for scopes, where ``send-updates`` is explicity
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set to ``enable``.
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This model is followed for a few behavioral settings below: if the option is
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not set, the setting is inherited from the parent scope. You can override the
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parent scope setting by setting the option explicitly.
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.. cfgcmd:: set service dhcp-server dynamic-dns-update override-no-update [ enable
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| disable ]
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VyOS will ignore client request not to update DNS records and send DDNS
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update requests regardless.
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.. cfgcmd:: set service dhcp-server dynamic-dns-update override-client-update [ enable
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| disable ]
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VyOS will override client DDNS request settings and always update both
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forward and reverse DNS records.
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.. cfgcmd:: set service dhcp-server dynamic-dns-update update-on-renew [ enable
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| disable ]
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Issue DDNS update requests on DHCP lease renew. In busy networks this may
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generate a lot of traffic.
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.. cfgcmd:: set service dhcp-server dynamic-dns-update conflict-resolution [ enable
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| disable ]
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Use RFC-4703 conflict resolution. This algorithm helps in situation when
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multiple clients reserve same IP addresses or advertise identical hostnames.
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Should be used in most situations.
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.. cfgcmd:: set service dhcp-server dynamic-dns-update replace-client-name [ never
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| always | when-present | when-not-present ]
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* **never**: use the name sent by the client. If the client didn't provide any,
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do not generate one. This is the default behavior
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* **always**: always generate a name for the client
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* **when-present**: replace the name the client sent with a generated one, if
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the client didn't send any, do not generate one
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* **when-not-present**: use the name sent by the client. If the client didn't
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send any, generate one for the client
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The names are generated using ``generated-prefix``, ``qualifying-suffix`` and the
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client's IP address string.
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.. cfgcmd:: set service dhcp-server dynamic-dns-update generated-prefix <prefix>
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Prefix used in client name generation.
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.. cfgcmd:: set service dhcp-server dynamic-dns-update qualifying-suffix <suffix>
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DNS suffix used in client name generation.
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.. cfgcmd:: set service dhcp-server dynamic-dns-update ttl-percent <0-100>
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TTL of the DNS record as a percentage of the DHCP lease time.
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.. cfgcmd:: set service dhcp-server dynamic-dns-update hostname-char-set
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<character string>
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Characters, that are considered invalid in the client name. They will be replaced
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with ``hostname-char-replacement`` string.
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.. cfgcmd:: set service dhcp-server dynamic-dns-update hostname-char-replacement
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<character string>
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Replacement string for the invalid characters defined by ``hostname-char-set``.
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**TSIG keys definition**
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This is the global list of TSIG keys for DDNS updates. They need to be specified by
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the name in the DNS domain definitions.
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.. cfgcmd:: set service dhcp-server dynamic-dns-update tsig-key <key-name>
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algorithm <algorithm>
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Sets the algorithm for the TSIG key. Supported algorithms are ``hmac-md5``,
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``hmac-sha1``, ``hmac-sha224``, ``hmac-sha256``, ``hmac-sha384``, ``hmac-sha512``
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.. cfgcmd:: set service dhcp-server dynamic-dns-update tsig-key <key-name>
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secret <key-secret>
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base64-encoded TSIG key secret value
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**DNS domains definition**
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This is global configuration of DNS servers for the updatable forward and reverse
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DNS domains. For every domain multiple DNS servers can be specified.
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.. cfgcmd:: set service dhcp-server dynamic-dns-update [forward|reverse]-domain
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<domain-name> key-name <tsig-key-name>
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TSIG key used for the domain.
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.. cfgcmd:: set service dhcp-server dynamic-dns-update [forward|reverse]-domain
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<domain-name> dns-server <number> address <ip-address>
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IP address of the DNS server.
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.. cfgcmd:: set service dhcp-server dynamic-dns-update [forward|reverse]-domain
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<domain-name> dns-server <number> port <port>
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UDP port of the DNS server. ``53`` is the default.
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**Example:**
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Global configuration you will most likely want:
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.. code-block:: none
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set service dhcp-server dynamic-dns-update send-updates enable
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set service dhcp-server dynamic-dns-update conflict-resolution enable
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Override the above configuration for a shared network NET1:
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.. code-block:: none
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set service dhcp-server shared-network-name 'NET1' dynamic-dns-update replace-client-name when-not-present
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set service dhcp-server shared-network-name 'NET1' dynamic-dns-update generated-prefix ip
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set service dhcp-server shared-network-name 'NET1' dynamic-dns-update qualifying-suffix mybigdomain.net
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And in a subnet within the same shared network:
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.. code-block:: none
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set service dhcp-server shared-network-name 'NET1' subnet '172.18.201.0/24' dynamic-dns-update qualifying-suffix mydomain.net
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Configure TSIG keys:
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.. code-block:: none
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set service dhcp-server dynamic-dns-update tsig-key mydomain-net algorithm hmac-sha256
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set service dhcp-server dynamic-dns-update tsig-key mydomain-net secret eWF5YW15bGl0dGxla2V5IQ==
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set service dhcp-server dynamic-dns-update tsig-key reverse-172-18-201 algorithm hmac-sha256
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set service dhcp-server dynamic-dns-update tsig-key reverse-172-18-201 secret eWF5YW15YW5vdGhlcmxpdHRsZWtleSE=
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Configure DDNS domains:
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.. code-block:: none
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set service dhcp-server dynamic-dns-update forward-domain mydomain.net key-name mydomain-net
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set service dhcp-server dynamic-dns-update forward-domain mydomain.net dns-server 1 address '172.18.0.254'
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set service dhcp-server dynamic-dns-update forward-domain mydomain.net dns-server 1 port 1053
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set service dhcp-server dynamic-dns-update forward-domain mydomain.net dns-server 2 address '192.168.124.254'
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set service dhcp-server dynamic-dns-update forward-domain mydomain.net dns-server 2 port 53
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set service dhcp-server dynamic-dns-update forward-domain 201.18.172.in-addr.arpa key-name reverse-172-18-201
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set service dhcp-server dynamic-dns-update reverse-domain 201.18.172.in-addr.arpa dns-server 1 address '172.18.0.254'
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set service dhcp-server dynamic-dns-update reverse-domain 201.18.172.in-addr.arpa dns-server 1 port 1053
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set service dhcp-server dynamic-dns-update reverse-domain 201.18.172.in-addr.arpa dns-server 2 address '192.168.124.254'
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set service dhcp-server dynamic-dns-update reverse-domain 201.18.172.in-addr.arpa dns-server 2 port 53
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High Availability
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-----------------
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@ -645,7 +826,7 @@ used:
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.. cfgcmd:: set service dhcpv6-server shared-network-name <name> subnet
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<prefix> prefix-delegation prefix <pd-prefix> excluded-prefix-length <length>
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<prefix> prefix-delegation prefix <pd-prefix> excluded-prefix-length <length>
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Define lenght of exclude prefix in `<pd-prefix>`.
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