win2008r2 to win2012r2 DC upgrades


  • I have a win2008r2 functional level domain & forest, consisting of a root & 2 child domains.

    All domain controllers are win2008r2 OS, except 1 win2012r2 in the root.  The 2012 holds no roles, but is a GC.

    The root has 2 physical win2008r2 DCs & 1 win2012r2 virtual.  Each child domain has 1 physical & 1 virtual DC.

    The child physicals need to be replaced in a few months & I was trying to decide about the upgrade plan. The physicals in the root will not be replaced until 2019.

    I am trying to keep all the DCs at the same OS level, but I am not sure if that is feasible or even necessary.

    The easiest plan would be to replace the child physicals with win2012r2, then build new 2012r2 VMs to replace the win2008r2 child VMs.  That way at least all the child domains would be upgraded to a current OS.

    However, would it cause any issues if the root DCs were running win2008r2 & all the child DCs were running win2012r2?

    Thursday, March 9, 2017 2:34 PM


  • Hi

     The point is functional level to your situation,cannot set the domain functional level to a value that is lower than the forest functional level.So if you don't raise FFL&DDL to server 2012,you can use both Server 2008 and server 2012 dc's on your domain.

     According to me i always prefer newset OS on DC's and also prefer same OS level on DC's.

    This posting is provided AS IS with no warranties or guarantees,and confers no rights. Best regards Burak Uğur

    Thursday, March 9, 2017 3:03 PM