SRV Record – Service Record:

SRV records are designed to provide information on available services for your systems, and they are used to help with service discovery.
An SRV record defines a symbolic name; the transport protocol used, the priority, weight, port and target for the service in the record content.

SRV Record Formatting:

SRV records have a unique system for naming. The naming format is an underscore, followed by the name of the service, followed by a period and underscore, and then the protocol, another dot, and then the name of the domain
_service._proto.name. TTL class SRV priority weight port target.
Service: the symbolic name of the desired service.
Proto: the transport protocol of the desired service; this is usually either TCP or UDP.
Name: the domain name for which this record is valid, ending in a dot.
TTL: standard DNS time to live field.
Class: standard DNS class field (this is always IN).
Priority: the priority of the target host, lower value means more preferred.
Weight: A relative weight for records with the same priority, higher value means more preferred.
Port: the TCP or UDP port on which the service is to be found.
Target: the canonical hostname of the machine providing the service, ending in a dot.