I needed to change the nic card in my backup domain controller. After doing so I had some issues in regards to a qhosted nic card retaining the same settings, after resolving that I replace my nic card. Now I cannot log in? I reinstalled the bad card and can get in, odd? I change the nic again, I wait 10 minuteds while it tries to authenticate and I can get in and then it ask that I ctrl alt del to verify the logon credentials, at that point I cannot get back in. Also, I had changed the Primary Domain passwrod about three months ago. I cannot log on with the new password only the old? That's when the credential issue comes up.

Your DC is trying to revert back to an old version of the AD schema.

Put the old NIC back into the machine and revert back to it. Even if it can not get to the network, put it back in. Logon with cached credentials and get to a desktop. You may have to wait 20-30 minutes before it finally comes up to a desktop.

Change the IP address of the old NIC to a different IP. Change the IP address of the new NIC to the desired IP for the DC. Disable the old NIC and reboot the server.

There should be no issues in changing the MAC address for your DNS and DHCP servers. We have done so without issue. But if the hardware was not properly removed, then a ghost entry remains in the registry. It thinks that there are two NICs with the same assigned IP address, etc.

Once you have successfully reassingned the new NIC, then properly remove the old hardware/device and drivers from the machine before physically removing the hardware.