I had a domain with two Server 2012 DCs: DC1 and DC2.
I decommissioned DC2 by removing the role, and had no problems. The domain appeared fine afterwards.
I then created two new Server 2012 R2 DCs: DC01 and DC02.
Again, there did not seem to be any issues with the domain and the three DCs appeared fine.
Next i transferred the FSMO roles from DC1 to DC01, then i tried to demote DC1 which complained repeatedly. I could not get DC1 to demote, and none of the logs showed the sources of the problem, so after following a Perti guide on removing a dead DC, forced the demotion of DC1 (just ticking the tick box to force it). That is when I realised that DC01 and DC02 were not sufficient, and the domain was lost.]
I used a System State backup of DC1 to recover that machine and the domain is back up again, users can log in once more, but there are many errors in DCDiag. I cannot ping the domain, and when I shut down DC1, the domain is once again inaccessible.
The main problems are:
Since restoring DC1 the computer object does not exist in the domain
I cannot ping the domain (Home.net)
I cannot manage the domain (AD Users and Computers) from either DC01 and DC02
DC01 and DC02 do not have SYSVOL or NETLOGON shares (appear to never have had since migrating the FSMO roles - why??)
WHAT I AM TRYING TO ACHEIVE:
I ultimately want to remove DC1 and keep DC01 and DC02, however, i understand this may not be possible. It IS an option to completely delete DC01 and DC02 and rebuild those machines from scratch (one physical and once VM).
My main concern is that I may lose the domain again.