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Difference between revisions of "SRV Records"
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Replace misleading "very important" heading for listing default port numbers.
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(Replace misleading "very important" heading for listing default port numbers.) |
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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]. | 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]. | ||
== Ports == | == Default Ports == | ||
* XMPP uses 5222 ('''C2S''') and 5269 ('''S2S''') ports in TCP only ([http://xmpp.org/rfcs/rfc6120.html RFC | === XMPP === | ||
* XMPP uses 5222 ('''C2S''') and 5269 ('''S2S''') ports in TCP only ([http://xmpp.org/rfcs/rfc6120.html RFC 6120]). | |||
=== STUN/TURN === | |||
* STUN uses 3478 port in TCP/UDP and STUNS (STUN over TLS) uses 5349 port in TCP only ([http://tools.ietf.org/html/rfc5389 RFC 5389]). | * STUN uses 3478 port in TCP/UDP and STUNS (STUN over TLS) uses 5349 port in TCP only ([http://tools.ietf.org/html/rfc5389 RFC 5389]). | ||
* TURN uses 3478 port in TCP/UDP and TURNS (TURN over TLS) uses 5349 port in TCP only ([http://tools.ietf.org/html/rfc5766 RFC 5766], [http://tools.ietf.org/html/rfc5928 RFC 5928]). | * TURN uses 3478 port in TCP/UDP and TURNS (TURN over TLS) uses 5349 port in TCP only ([http://tools.ietf.org/html/rfc5766 RFC 5766], [http://tools.ietf.org/html/rfc5928 RFC 5928]). | ||
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* '''name''': the domain name for which this record is valid. | * '''name''': the domain name for which this record is valid. | ||
* '''TTL''': standard DNS time to live field. | * '''TTL''': standard DNS time to live field. | ||
* '''class''': standard DNS class field (this is always ''IN''). | * '''class''': standard DNS class field (this is always '''IN'''). | ||
* '''priority''': the priority of the target host, lower value means more preferred. | * '''priority''': the priority of the target host, lower value means more preferred. | ||
* '''weight''': A relative weight for records with the same priority. | * '''weight''': A relative weight for records with the same priority. | ||
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_stun._tcp.example.net. TTL IN SRV priority weight port target | _stun._tcp.example.net. TTL IN SRV priority weight port target | ||
_stun._udp.example.net. TTL IN SRV priority weight port target | _stun._udp.example.net. TTL IN SRV priority weight port target | ||
_stuns._tcp.example.net. TTL IN SRV priority weight port target | |||
=== Example 1 === | === Example 1 === | ||
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_turn._tcp.example.net. TTL IN SRV priority weight port target | _turn._tcp.example.net. TTL IN SRV priority weight port target | ||
_turn._udp.example.net. TTL IN SRV priority weight port target | _turn._udp.example.net. TTL IN SRV priority weight port target | ||
_turns._tcp.example.net. TTL IN SRV priority weight port target | |||
=== Example 1 === | === Example 1 === | ||
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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 server1 is down, server2, server3 and server4 will work, if servers 1/2/3/4 are down, backup will work. | 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 server1 is down, server2, server3 and server4 will work, if servers 1/2/3/4 are down, backup will work. | ||
=== Retrieving | === Retrieving TURN SRV records === | ||
$ dig SRV _turn._tcp.example.net | $ dig SRV _turn._tcp.example.net | ||
$ dig SRV _turn._udp.example.net | $ dig SRV _turn._udp.example.net | ||
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* [http://tools.ietf.org/html/rfc2782 RFC 2782: A DNS RR for specifying the location of services (DNS SRV)] | * [http://tools.ietf.org/html/rfc2782 RFC 2782: A DNS RR for specifying the location of services (DNS SRV)] | ||
* [http://xmpp.org/rfcs/rfc6120.html RFC 6120: Extensible Messaging and Presence Protocol (XMPP): Core] | * [http://xmpp.org/rfcs/rfc6120.html RFC 6120: Extensible Messaging and Presence Protocol (XMPP): Core] | ||
* [http://tools.ietf.org/html/rfc5389 RFC 5389: Session Traversal Utilities for NAT (STUN)] | |||
* [http://tools.ietf.org/html/rfc5766 RFC 5766: Traversal Using Relays around NAT (TURN): Relay Extensions to Session Traversal Utilities for NAT (STUN)] | |||
* [http://tools.ietf.org/html/rfc5928 RFC 5928: Traversal Using Relays around NAT (TURN) Resolution Mechanism] | |||