You must update the Active Directory schema before you can add a domain controller running Windows Server 2008 to the Active Directory environment running Windows Server and Windows Servers 2003. You must update the schema on the domain controller that owns the schema operations master role. If you plan to perform a Windows Server 2008 AD DS unattended installation, you must update the schema before you install the operating system. If the installation is normal, you must update the schema after you run "Setup" and before you install AD DS.
After you have configured the active forest, you need to configure any domain that you plan to install to run the Windows Server 2008 domain controller. For more information about this, read the article configure Windows Server or Windows Server 2003 Active Directory domain for domain controllers running Windows Servers 2008.
If you are creating a new Windows Server 2008 active forest, you do not have to configure the schema or any domains in the forest.
Use the following steps to update the Windows Server 2003 or Windows SQL Server active forest schema for Windows Server 2008 domain controllers.
Manage Credentials
In order to perform this step, you must use a group membership account with all of the following groups:
L Enterprise Admins
L Schema Admins
L domain Admins of domains containing schema master
To configure a forest schema for Windows Server 2008
1. Log on to the schema master with Enterprise Admins, schema Admins, and Domain Admins groups group memberships
2. Insert the Windows Server 2008 DVD disc to the DVD drive. Copy the contents of the Sourcesadprep folder to the Adprep (self-created) folder on the schema master.
3. Open command prompt, change directory to adprep folder
4. At the command prompt, enter the following command and return to:
Adprep/forestprep
5. If you plan to install an RODC in any domain in the forest, enter the following command and return:
Adprep/rodcprep
6. Allow the operation to complete, and then allow the updates to be replicated throughout the forest before you configure any domains for the Windows Server 2008 domain controller.