Add Windows Server 2012 DC in existing 2008R2 without updating schema

Solution 1:

No...it isn't possible. The schema has to be updated.

Here's the list of what is changed: http://technet.microsoft.com/en-us/library/jj916256.aspx

Solution 2:

No it is not possible. Server 2012 schema version is 56.

You must update your schema before a Server 2012 domain controller is allowed in your forest.

Adprep is now baked into Add-ADDomainController and Server Manager and will run automatically if needed when promoting a Server 2012 DC.

But I still prefer to run adprep myself because I'm used to it. Copy the adprep folder from \support\adprep on the Server 2012 install media.

Then run adprep /forestprep. That should get you to schema version 56.

Wait for replication throughout the forest.

Then run adprep /domainprep.

Solution 3:

Just in case you're not aware: You DO have to update the schema to support DC's running newer Operating systems, but you DO NOT have to raise the Domain or forest functionality level, meaning you can keep older DC's in situ.

As an example: I have a 2012R2 Domain Controller, running on the 2003 Forest and Domain functionality level: I can have any DC's from 2003 - 2012 R2 on that network: Only 2000 DC's are excluded.