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.