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New page: A Service record (SRV record) is a specification of data in the Domain Name System (DNS) defining the location, i.e. the hostname and port number, of servers for specified services. It is ...
A Service record (SRV record) is a specification of data in the Domain Name System (DNS) defining the location, i.e. the hostname and port number, of servers for specified services. It is defined in [http://tools.ietf.org/html/rfc2782 RFC 2782].

XMPP often require SRV support by network elements.

== Record format ==
An SRV record has the form:
_service._proto.name TTL class SRV priority weight port target

* ''service'': the symbolic name of the desired service.
* ''proto'': the transport protocol of the desired service; this is usually either TCP or UDP.
* ''name'': the domain name for which this record is valid.
* ''TTL'': standard DNS time to live field.
* ''class'': standard DNS class field (this is always ''IN'').
* ''priority'': the priority of the target host, lower value means more preferred.
* ''weight'': A relative weight for records with the same priority.
* ''port'': the TCP or UDP port on which the service is to be found.
* ''target'': the canonical hostname of the machine providing the service.

== XMPP SRV records ==
_xmpp-client._tcp.example.net. TTL IN SRV priority weight port target
_xmpp-server._tcp.example.net. TTL IN SRV priority weight port target

=== Example 1 ===
_xmpp-client_tcp.example.net. 86400 IN SRV 5 0 5222 example.net.
_xmpp-server._tcp.example.net. 86400 IN SRV 5 0 5269 example.net.

The XMPP domain is example.net and the server is example.net.

=== Example 2 ===
_xmpp-client_tcp.example.net. 86400 IN SRV 5 0 5222 server.example.net.
_xmpp-server._tcp.example.net. 86400 IN SRV 5 0 5269 server.example.net.

The XMPP domain is example.net and the server is server.example.net.

=== Example 3 ===
_xmpp-client_tcp.example.net. 86400 IN SRV 5 50 5222 server1.example.net.
_xmpp-client_tcp.example.net. 86400 IN SRV 10 30 5222 server2.example.net.
_xmpp-client_tcp.example.net. 86400 IN SRV 10 10 5222 server3.example.net.
_xmpp-client_tcp.example.net. 86400 IN SRV 10 10 5222 server4.example.net.
_xmpp-client_tcp.example.net. 86400 IN SRV 15 0 5222 backup.example.net.
_xmpp-server._tcp.example.net. 86400 IN SRV 5 50 5269 server1.example.net.
_xmpp-server._tcp.example.net. 86400 IN SRV 10 30 5269 server2.example.net.
_xmpp-server._tcp.example.net. 86400 IN SRV 10 10 5269 server3.example.net.
_xmpp-server._tcp.example.net. 86400 IN SRV 10 10 5269 server4.example.net.
_xmpp-server._tcp.example.net. 86400 IN SRV 15 0 5269 backup.example.net.

The XMPP domain is example.net and the principal server is server1.example.net which used 50% after server2.example.net 30%, server3.example.net 10%, server4.example.net 10% too, if server 1 is down, server2, server3 and server4 will work, if servers 1/2/3/4 are down, backup will work.

== Retrieving SRV records ==
$ dig SRV _xmpp-client._tcp.example.net
$ dig SRV _xmpp-server._tcp.example.net
190

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