Should I specify the SRV record "_jabber._tcp"?
Solution 1:
The _jabber SRV resource record is deprecated. Don't worry about it unless you want to support old, legacy clients.
http://mailman.jabber.org/pipermail/jadmin/2007-January/098908.html
SRV records are described in RFC 2782. They are DNS records that applications can use to locate services on the network.