The SRV record

The SRV (service) record is an enhancement of the A and AAAA records, used to return not just addresses, but address–port combinations.

Example

Here, we query for SRV records of the domain caa-example.lookup.dog. The result is a record that specifies a service with the address dns.lookup.dog:5000, with priority 10 and weight 20.

$ dog SRV srv-example.lookup.dog
SRV srv-example.lookup.dog. 1h00m00s   10 20 "dns.lookup.dog.":5000
  A dns.lookup.dog.           53m49s + 138.68.117.94

In the Additional section of the response, specified by the + character, the IPv4 address of the service is also returned, to save another request from being made.