RFC 974 - Mail Routing and the Domain System

Tue Sep 15 21:02:23 UTC 1998

> 	My imperfect understanding of how most mail agents handle MX records is
> that with the first configuration, mx1 will always be tried first,
> followed by mx2, etc. With the second configuration, a BIND server will
> return the A addresses in an effectively random pattern, so load should
> be distributed across the 3 servers. 

Indeed if the MXes have different priorities, only in this case they have
the same priorities so they will also be load balanced. (The key being,
BIND will round robin any kind of record, not just A records).

I tried to answer this question earlier but couldn't come up with a good
answer so I kept quiet :-(

-Phil