Internal domains

[Josh.Sakofsky at donovandata.com]

I have a domain (say, acme.org) that is now being served by a Raptor 
Firewall.  The raptor can create records as public or private within the 
same domain.  I would like to move over to BIND, and was curious how I 
could accomplish that same type of setup without using a sub-domain.  My 
thought is that I can include the internal a records on the server that 
handles the acme.org zone, and if I don't allow domain transfers that 
would be sufficient.  Can anyone think of a problem with this model and/or 
a solution that might be better? Thanks!

-joshs