DNS on Windows Server 2003, 3rd Edition

3. Name Server Loses Manual Changes

One final but important note about making manual changes: remember that the Microsoft DNS Server periodically updates its zone datafiles. Each time you make changes to a zone’s data using the DNS console, a write is pending: before the name server exits, it must rewrite the zone’s datafile or it will lose the changes you made. Think of this as a dirty page in memory: the operating system must write it to disk before exiting.

If you make a manual change to a zone datafile while a write is pending, you’ll mysteriously lose the change when the name server exits. Say you add delegation to a new subdomain of movie.edu while the server is running and a write is pending. After you’ve made the change, you have to stop the server and start it again to get it to read the zone data again. But as the server exits, it rewrites the movie.edu zone datafile, and your delegation disappears. If you’re watching the DNS Server event log carefully (like you should be), you’ll see a message like this before the server stops:

The DNS server wrote version 37 of zone movie.edu to file movie.edu.dns.

Once you force the server to rewrite its zone datafiles with Action → Update Server Data Files, the server is in sync with the zone datafiles and doesn’t have to rewrite them on exit. So, if you’re going to make manual changes to the zone datafiles, you should either stop the server first (although that means your server won’t answer queries while you make the change), or ...