DNS/named.conf setup question

[asheets]

Say I have a domain somefakedomain.com. I have been asked to set up a BIND installation that will do the following:

1) be authoritative for mail.somefakedomain.com at address 10.0.192.132

2) refer queries to for all other server names in somefakedomain.comto another DNS server at 10.0.128.6 . Incidentally, DNS server 10.0.128.6 returns mail.somefakedomain.com==10.0.5.5, which is correct for the majority of machines pointing to 10.0.128.6, but not correct for the 100 or so that will be getting DNS from this new DNS server. Essentially, the 100+ machines are in a division that needs to be pointed to a different mail.somefakedomain.com by pointing at a different DNS box, not by changing hosts files or changing mailserver names on the client.

3) answer queries for all other domains, either by forwarding to a root server or to 10.0.128.6

Everything I've tried so far yields 2 out of the 3, but not all three. Anybody got anything for me?

[asheets]

Figured it out. Instead of me trying to override the authoritative somefakedomain.com zone file, I created a new zone file for mail.somefakedomain.com and pointed the appropriate IP at the new zone itself.

A bit of a cludge, and definitely not the way it is supposed to work, but it does work as needed.