20

On a domain, in the DNS settings is an SRV record named:

_autodiscover._tcp

and value is:

0 10 443 autodiscover.*hostname*.net.

What is it and what does it do?

I am migrating websites to a new server and I need to know how this will work with the new server on a different host.

christoflee
  • 305
  • 1
  • 2
  • 8

2 Answers2

23

SRV DNS records allow the use of DNS for publishing services and service discovery. Their main use is to allow services to run easily on non-standard ports and to reduce the configuration burden when setting up clients.

A SRV record has the following form:

_Service._Protocol.Name. TTL Class SRV Priority Weight Port Target
  • Service: the symbolic name of the service.

  • Protocol: the transport protocol of the service; this is usually either TCP or UDP.

  • Name: the domain name terminated with a . for which this record is valid - often omitted in DNS shorthand which then defaults to the zone name.

  • TTL: standard DNS time to live field.

  • Class: standard DNS class field (this is always IN for Internet).

  • 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.

Yours appears an example of an autodiscovery service :) pointing to TCP port 443 on the aptly named host autodiscover.*hostname*.net.

One such autodiscovery service seems to be used in automatically configuring MS Outlook but that may not be the only use-case.

HBruijn
  • 72,524
  • 21
  • 127
  • 192
5

It is likely related to your Exchange server.

Autodiscover for Exchange.

ThatGraemeGuy
  • 15,314
  • 12
  • 51
  • 78
  • 2
    Absolutely, and it allows Outlook to "discover the Exchange autodiscover service", whatever that means. See also: [A new feature is available that enables Outlook 2007 to use DNS Service Location (SRV) records to locate the Exchange Autodiscover service](https://support.microsoft.com/en-us/kb/940881). Not all domains may have it, so I suppose this is used to override a default that Outlook tries. Looks like there is an IIS server at the endpoint indicated. – David Tonhofer Jun 22 '15 at 10:16