A SRV record called as a Service record provides information on available services.
The SRV record has four fields. The naming convention of the SRV record is unique. Following is the naming syntax:
_<SERVICENAME>._<PROTOCOL>.<DOMAINNAME>
Where,
SERVICENAME is the name of the service
PROTOCOL is the name of the protocol ex: TCP
DOMAINNAME is the name of the domain.
An example would be,
_ftp._tcp.itsyourip.com.
The record itself has four fields in it namely,
1. Priority
2. Weight
3. Port
4. Hostname
An example record would look like the following:
_ftp._tcp.itsyourip.com. 86400 IN SRV 10 10 21 ftp.itsyourip.com.