An SRV (Server) DNS record is used to determine the availability of a specific service using a particular protocol for a given domain. It allows multiple servers to be specified, priorities to be defined between them, and the port on which the service runs to be indicated.
Structure:
_Service._Proto. Name TTL Class SRV Priority Weight Port Target
Example:
_http._x.example.com. 3600 IN SRV 10 20 8000 x.example.com.
The purpose of an SRV record is similar to that of the older MX record, which was traditionally used for email services. In fact, the SRV record can be considered a generalised version of it: instead of being limited to email, SRV records can be used to define the location of any type of service.
Multiple SRV records can be configured for the same service. These can be organised using the Priority and Weight parameters, and they also allow you to specify the protocol used and the port number on which the service is provided.