Also known as a service record is a type of DNS TXT entry or resource record used to define the hostname and port number of servers for specified services. It is used when configuring SIP (session initiation protocol) or another third-party service.
When a web application (e.g. audio or video streaming services, voice-over IP, instant messaging, etc.) needs to locate a specific service’s hostname and port number, it will search for the related SRV record. If it finds one, it will filter through the list of services along with their connecting hostnames to find the following:
- Hostname
- Ports
- Priority and weight
- IP addresses (if relevant)