We have 3 x DC's on site. We are in the process of upgrading them all to 2012r2.
Yesterday I began with first one, a 2008r2 machine ("DC3") which I was doing an in-place upgrade to 2012r2 (yeah, I know that this was a mistake now).
This server does NOT have any FSMO roles.
Everything seemed to go fine with the in-place upgrade until I installed the 250+ Windows updates. When I rebooted the server just hang on the loading screen. I tried everything to get it going, but I had no luck. After trying to fix boot records etc the machine was even trying to boot into its old 2008r2 OS. Not good.
In the end I had to admit defeat and rebuild the machine from scratch. I gave it the same name and IP address.
However, as I was not able to cleanly demote this DC I had to perform a metadata cleanup.
Once I had completed the metadata cleanup, I added the rebuilt DC to the domain and promoted it via the GUI. I had a couple of snags regarding the GUI hanging on "Creating the NTDS settings object", but I was able to resolve it by following this fix:
(in particular the comment by fulloutpullin)
So, everything appeared to complete OK, but I have some problems....
1.) If I look in AD sites and Services, the new DC is there but the NTDS settings are empty.
2.) If I open DNS on one of the other two DC's and try to add DC3 it fails.
3.) I cannot ping or RDP to DC3 (the firewall is off)
I need help to know what to do next!
Should I attempt to fix the problem?
Should I demote DC3 again (hoping it does it cleanly), rebuild the server from scratch and start again with a different name and IP?