DNS issues come up quite a bit on web boards and mailing list. Recently there have been a flurry of questions related to DNS publishing. This could be because of the recent attacks to the root DNS servers or because of the Windows DNS server vulnerability a couple of weeks before. However, Thomas Shinder put together a good overview of different szenarios how to protect DNS servers behind a firewall and how to publish them:

Part 1: http://www.isaserver.org/tutorials/DNS-Publishing-Scenarios-Part1.html
Part 2: http://www.isaserver.org/tutorials/DNS-Publishing-Scenarios-Part2.html

Urs