Setting up DNS in DMZ

I'm looking for examples of a correct way to set up a dns in a DMZ -- a
hardware DMZ. Not setting up named on a system that has a firewall, but
setting up named in the DMZ.

Of course, on a firewall, there is the registered ip range, and 2 private
ranges. The dns is for the registered ip range, however, it is set in one of
the private ranges. So, what is appropriate for configuring the dns?