I am migrating an Active Directory Domain from Server 2012 to Server 2016. Everything I've read says that simply setting up the 2016 server as a replica and then transferring FSMO roles to the new server should be it. I've found this not to be the case. I have verified that the FSMO roles have been transfer to Sevrer 2016, but when I shutdown the 2012 server, I am not able to connect to Active Directory from my 2016 server.
Perhaps it is something wrong with DNS? Some of my machines are resolving the 2012 server and some are resolving the 2016 server when I ping my domain. My 2016 server is even resolving to the 2012 server when I ping my domain. I've check my SOA in DNS settings and that is pointing to the 2016 server.
I've tried to uninstall AD services from the 2012 server, but I get this: "No other domain controllers could be contacted, but other domain controller objects are in the directory. If you are certain that this is the last domain controller for the domain and want to proceed, confirm that this is the last domain controller in the domain."