This is the first part of 2 posts for migrating Active Directory from 2008 to 2012. This post will cover the per-requisites required to migrate AD. It is important to note, that once the schema version has been upgraded, it will not be possible to deploy a domain controller below the new functional level. I.E if running at Server 2012 R2, a Server 2008 Domain Controller can not be deployed again.

Lets get started – In order to deploy Server 2012 R2 or any later version of Windows Server as a domain controller than your forest functional level, we must prep the AD schema for the target version.

First, we must check which version the current schema sits at – below is a table of functional levels and their respective schema versions.

You can check the version by executing the following command:

dsquery: dsquery * CN=Schema,CN=Configuration,DC=Root-Domain -Scope Base -attr objectVersion

or by viewing the following entries in the local registry hive on your primary domain controller or within ADSIEdit:

• Registry: HKLM\SYSTEM\CurrentControlSet\Services\NTDS\Parameters\<Schema Version>
• ADSIEdit: open ADSIEdit and navigate to “CN=Schema,CN=Configuration,DC=domain,DC=local”, right-click “Properties” and locate “objectVersion” attribute value

I have confirmed that my current schema version is 44 which correlates with my Domain Controller OS Version, Server 2008.

Next, we must obtain the ADPrep binaries located on the OS Install Media for the version we are looking to upgrade to.

Copy the binaries to the root of the C drive of your primary domain controller.

Ensure the account you are logged in with is a member of the Schema Admins group and open a elevated command prompt and point to the newly copied ADPrep binaries.

First we will run the following command to prepare the domain for the new schema updates

adprep /domainprep

Next we will run the following command to prepare the forest for the new schema updates.

adprep /forestprep

When executing this command, you will be shown the current schema version and the target schema version – in our instance, we are going to schema version 69.

Pre-reqs complete, we can now move on and deploy our new Server 2012 R2 Domain Controller.