What is '_autodiscover._tcp' in DNS settings?

Solution 1:

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.

Solution 2:

It is likely related to your Exchange server.

Autodiscover for Exchange.