Use of MX records

[Phyllis Melvin]

I've just installed BIND as a client (on Ultrix 3.1) and have
discovered some odd behavior.  When Ultrix queries the domain server
to determine how to send mail to a host, it FIRST asks for Address 
records.  If the domain server returns one, Ultrix tries to connect 
to that address.  It doesn't ask for an MX record!  It only asks for 
an MX record if the request for an Address record returns nothing.

This behavior is contrary to my understanding of the RFCs.  Shouldn't
Ultrix FIRST ask for MX records and use them if they exist?  As it is,
I find mail failing (the host won't accept connections, or the network
is unreachable, etc.) when it should have been readily deliverable.

Is my understanding of the RFCs wrong? Or is Ultrix doing the wrong 
thing?

-- 
Phyllis Melvin 
uucp:      uw-beaver!bcsaic!phyllis
internet:  phyllis at atc.boeing.com