First, reference back to my first post on Domain Controller IP/Subnet changes. The nice thing about changing IP addresses on DCs in a larger environment, is that itís actually easier. I have to keep this one quick for now, but will expand based on comments, which you all seem pretty good at leaving (and thank you!). Please, PLEASE refer back to the first post – this one is only an expansion on that one.

  1. Same as before: why are you changing IPs? In larger environments, I do this because of a physical move of just one site. If the networking team doesnít have the new subnet up and routing, donít start!
  2. Make sure the new site (if required) is set up in AD. If Iím moving DCs from one physical location to another, I will build a new site, rather than re-using the old one, because the new site often has better connectivity, so the site link costs are changing.
  3. Add the new IP to the DC youíre moving (DC01 for this). Same as before: donít remove the old one, just add the new.
  4. On DC01, do the following to verify registration worked:
    ipconfig /registerdns
    Wait a few minutes.
    nslookup
    server DC01
    set type=A
    DC01.foobar.local
    foobar.local
    server DC02
    DC01.foobar.local
    foobar.local

    The answers from DC01 and DC02 should be the same, with possibly different orders. The important thing is that the new IP address and the old IP address show up for both queries on both servers.
  5. Shut down DC01, pack it up and move it. (Or just plug it into the new network.)
  6. Boot up, verify that DC01 has network connectivity, and that other systems can see that it has the new IP.
  7. If you havenít, make the new IP primary (change order in Network settings), make sure the DNS and WINS servers are correct and reachable (Remember that Windows 2003 DNS should point to itself).
  8. Once verifying that AD is replicating across sites properly (up to 15 minutes in my experience), remove the old IP, ipconfig /registerdns, and reboot.
  9. When it comes back up re-verify that AD is still replicating, and you should be set.

I would point out that when doing a change this big to your environment, reviewing your AD replication, DNS forwarding, and WINS topology is a good idea.