RFC 3861, SRV handling

Hi folks,

According to RFC 3861, the destination server of an instant messaging address 
can be determined by doing an SRV lookup on the domain name within that 
address.  For example, if you want to send a message to an address via XMPP, 
one might do a lookup on:

  _im._xmpp.example.com

However, what confuses me is how this is supposed to play with XMPP's own 
delivery procedure, particularly regarding the fact that XMPP uses SRV as 
well.  For example, when one XMPP server delivers a message to another, the 
sending server does an SRV lookup:

  _xmpp-server._tcp.example.com

Should both of these SRV lookups produce the same set of hostname/port pairs, 
meaning that they are two ways to do the same thing and the sender can just 
pick one?  Or should these procedures be "stacked", such that the _im._xmpp 
lookup would result in a domain name that would in turn be passed through the 
_xmpp-server._tcp lookup?

Thank you,
-Justin

  [reminder: [email protected] for non-technical discussions, please]