I've got a 2012 R2 server in 2003 functionality mode. I am building out a server 2022 and need to get the functionality mode to 2012 R2 for an Exchange 2013 to Exchange 2019 migration.
From what I've read I'll need to baby step the domain functionality up step-by-step, testing AD functionality and Exchange 2013 functionality with each step. Eventually will decom the 2012 R2 DC but that doesn't need to happen till the end. I think to migrate to 2012 R2 functionality level I need to enable DFSR AD replication, so I'll do that before the functional level increase to 2012 R2.
Any caveats in this plan? I do need to be cognizant of a working Exchange 2013 server on the domain.
Also, when is it recommended to raise the functionality level of the forest, eventually. Is that recommended at the very end?
