Active Directory & Integrated DNS holding on to DNS name that has been reassigned

Flight5497 used Ask the Experts™
Hi Experts,

In our head office we have 4 domain controllers at present. 2 are the original domain controllers than have been in place for some time, and the other 2 are the new windows server 2008 r2 servers that have been setup to eventually replace the older 2.

All 4 are running DNS Server roles and are part of AD Intergrated DNS. I have moved all the FSMO roles that were on one of the older domain controllers and placed it on one of the new ones with the look to demoting the older 2 and eventually removing them from the system entirely.

Last night I started that processes. I demoted the first server which went well, I then removed all remnents on the DNS Role on the machine. Now DHCP assigns this old server as the primary DNS address for the network.

So my thought process was it is no longer a domain controller, or DNS server what I will do is place this servers network card to DHCP, reboot the server let that take hold.

Then what I did was assign the new server with the IP Address that was on the old primary. Now the problem I have hit is when I RDP or ping the name of the new server it tells me it has the ip address of which is correct.

I had a look on the DHCP server to see what the old server ip address was now and it was listed as, however whenever I try and ping it by name or rdp to it by name it still pings!

I checked all the DNS servers to make sure there was not a rogue entry anywhere in the Name Server listings and also any other A Records pointing to something it should not be and there is nothing!

Yet it still tries to resolve the name to the address, I have checked the replication and everything looks fine there, i have checked the DNS and as far as I can see everything looks fine there.

I am kind of stumped as to where it is holding this last reference to that machine.

Is it possible to reuse an address that was used for a DNS Server that is no longer a DNS Server?

Any help will be gratefully received.
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Yes, it's possible, but remember that domain controllers don't like their IP addresses changed without changing other things.  I can't tell from your description if you did that or not.

A few thoughts:

1) DHCP and DNS are different.  DHCP passes out IP addresses and settings.  DNS looks up IP addresses.  I'm sure you know this, but don't think they are otherwise related.
2) On the computer you are testing from, perhaps the DNS information is cached still from when it was wrong.  Try an "ipconfig /flushdns" to make it ask the DNS for fresh information.
3) Double-check the DHCP server or scope options to make sure it is passing out the correct information to clients.
4) If you did change the IP address of the domain controller/DNS server, you may need to re-register all of its DNS entries with a command like "nltest /dsregdns"  There may be other things you need to do, but that's beyond the scope of this question.

Hope that helps you get the network figured out!
It is not an issue changing the IP of the DC. Once you change the IP of the DC run ipconfig /flushdns and ipconfig /registerdns. You can also restart DNS and Netlogon service to refresh the SRV records.

If it still reslove the IP to the old , look for the name server tab in DNS, in all the folder inside _msdcs folder.

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