I have a active directory that have several domain controllers spread across several sites. All the current domain controllers are running Windows 2008 R2 except one domain controller.
The forest and domain functional level is Windows 2008 and I am not able to raise this level (highest).
I have two new domain controllers that I would like to deploy in my domain. These new domain controllers are running Windows server 2012 R2.
I started to promote one of the servers that is running server 2012 R2 but the AD promotion process wants to upgrade the following:
Forest prep, domain, and schema prep.
My main concerns are:
What will be the effect on the above actions? Will the domain controller with windows 2008 still work after the the new 2012 Dc is promoted?
Will this mess up anything on the other dc at the other site?
What would be the domain and forest level after the new DC (2012) is promoted.
What OS would the client machine have to have in order to work on the domain?