9. Usage rules

A SRV-cognizant client SHOULD use this procedure to locate a list of servers and connect to the preferred one:

        Do a lookup for QNAME=_service._protocol.target, QCLASS=IN,
        QTYPE=SRV.

        If the reply is NOERROR, ANCOUNT>0 and there is at least one
        SRV RR which specifies the requested Service and Protocol in
        the reply:

            If there is precisely one SRV RR, and its Target is "."
            (the root domain), abort.

            Else, for all such RR's, build a list of (Priority, Weight,
            Target) tuples

            Sort the list by priority (lowest number first)

            Create a new empty list

            For each distinct priority level
                While there are still elements left at this priority
                level

                    Select an element as specified above, in the
                    description of Weight in "The format of the SRV
                    RR" Section, and move it to the tail of the new
                    list

            For each element in the new list

                query the DNS for address records for the Target or
                use any such records found in the Additional Data
                section of the earlier SRV response.

                for each address record found, try to connect to the
               (protocol, address, service).

        else

            Do a lookup for QNAME=target, QCLASS=IN, QTYPE=A

            for each address record found, try to connect to the
           (protocol, address, service)