dig oddness, or perhaps my lack of understanding?

Heres the deal, about a month ago(I just remembered), I was at a clients
site resolving some exchange server problems in a typical small business
microsoft network. I was testing dns resolution and ran across the
strangest thing.

from my laptop (linux) I would run

dig @4.2.2.2 dnsnamehere.com MX

its my understanding that it is supposed to query only 4.2.2.2 for this
answer. I got a reply of 192.168.1.11 the inside address for the mail
server (i am in their network at this moment). However if I test from
4.2.2.2 (or any other dns server) from outside their network I get the
correct outside address.

the dns files do not have the inside address's in them so how could I be
getting this internal address? it doesn't make any sense.

Thanks.

--
Entelin <entelin@users.sourceforge.net>