You’ve migrated all your zones from DNS servers running Windows Server 2003 to DNS servers running Windows Server 2012 R2. What do you need to do next?
In no particular order, ensure that you do the following:
- You’ll need to decommission the DNS servers running Windows Server 2003. If you’ve performed the migration correctly, none of them will currently be functioning as primary zone servers.
- You’ll need to reconfigure DHCP scopes with the addresses of the new DNS servers. This is a straightforward task.
- You’ll need to reconfigure clients that have the DNS server addresses statically configured. This can be challenging because, unless your organization is great at documenting configurations, you might not be aware which computers have their DNS configuration assigned statically.
It isn’t just computers that might have DNS configuration assigned statically. Some applications have DNS server addresses assigned statically. Before switching them off, you will want to be sure that the DNS servers are not responding to requests. You can do this by configuring logging and determining whether any queries are coming through. Or you can use the more “blunt stick” approach of turning off the computer and seeing if anyone starts screaming.
Because it can be hard to determine how DNS server addresses have been configured, it’s not uncommon for admins to just assign the new DNS server the old DNS server’s IP address.