SRV-Records (location of service)

SRV-records are used to specify the location of a service.

They are used in connection with different directory servers such as LDAP (Lightweight Directory Access Protocol), and Windows Active Directory, and more recently with SIP servers (see https://simpledns.plus/kb/112).

The SRV record identification (record name) is made of of 3 parts:

  • Service: Most internet services are defined in RFC1700 (page 15).

  • Protocol: Generally TCP or UDP, but other values are also valid.

  • Domain name.

The "service location" is specified through a priority, weight, port and target:

  • Priority is a preference number used when more servers are providing the same service (lower numbers are tried first).

  • Weight is used for advanced load balancing.

  • Port is the TCP/UDP port number on the server that provides this service.

  • Target is the domain name of the server (referencing an A-record or AAAA-record).

To create a new SRV-record, right-click a zone in the left list in the DNS Records window, and select "Other new record" from the pop-up menu.

This record type is defined in RFC2782.

Note: While this record type could potentially have been used by web-browser software (to locate web-servers), this was never implemented by any major browsers. Instead browsers have recently (2021) started supporting the HTTPS record-type which provdides similar functionality specifically for web-sites.

 Comments
Gravatar
8 Oct 2019 15:07 UTC
Kristian
Sentense: "Protocol: Generally TCP or UDP, but also values are also valid.". Do you mean that also numerical values are accepted besides typing "TCP" or "UPD"?
JH Software
17 Dec 2019 23:37 UTC
JH Software
This would most likely be letters (not numbers) - and almost always either UDP or TCP - but this depends entirely on the application using the service.
(Never published. Used for replies and to show your Gravatar icon. Never used for any other purpose.)
Connect