DNS and Firewalls

Here’s the deal:

Running Win2K server. Three DCs. All Running DNS
#1 On the DMZ of a 3Com firewall-public IP addy
#2 Behind the firewall, private IP, NAT to a public addy
#3 Behind a remote firewall, private IP, NAT to a public addy

The problem:
The two DCs behind the firewalls, register their private IP addresses to
DNS. The DC on the DMZ, can’t reach them via the private IPs. I have tried
adding a second A record in DNS with the public IPs, but when they register,
the public IPs go away.

As you can imagine, this plays havoc with replication.

I tried adding the IPs to the DMZ DC’s Hosts file, but this doesn’t seem to
do any good.

Any thoughts? Anyone?