Upgrade Windows Server 2008 r2 standard to Server 2012 R2 standard

Solution 1:

I'm not sure why @whizkid thinks Microsoft doesn't recommend in-place upgrades. That might have been the case way back in the 2000/2003 era of Windows. But ever since the Win7/2008R2 generation of Windows, in-place upgrades have been pretty well supported. In fact, it has basically become the new default for desktop OSes. Just look in the tech news for all of the annoyed reports from people getting auto-upgraded from Win7/8/8.1 to Win10.

I've personally performed a decent number (10+) of in-place upgrades from 2008 R2 to 2012 R2 on domain controllers in production environments without any issues whatsoever (aside from the expected downtime during the upgrade process). Admittedly, most of those were running nothing but DC related services. But in any case, I wouldn't let the fact that the machine is DC stop you from attempting an in-place upgrade. But as always, have backups just in case.