Answer: In order to use many of Windows Server 2008 and Windows Server 2008 R2 new function we need to raise the domain and forest functional level.
Before using this KB you will have to prepare you your domain controller for windows server 2008 R2 domain controller which mean that your DC needs to run windows server 2008 R2.
To raise the domian functional level to Windows Server 2008 R2 follow the steps below:
Step 1: Raise Domain Functional Level.
Open Active Directory Domain And Trusts.
Right Click on your domain name and click on Raise Domain Functional Level.
You will see the options (I will use R2).
And OK again.
Step 2 Raise Forest Functional Level.
Open Active Directory Domain And Trusts -> Right click on the domain name and click on Raise Forest Functional Level.