Figure-1

Figure-3

0 = Forest functional level: Windows 2000
1 = Forest functional level: Windows Server 2003 interim
2 = Forest functional level: Windows Server 2003
3 = Forest functional level: Windows Server 2008
4 = Forest functional level: Windows Server 2008 R2
5 = Forest functional level: Windows Server 2012


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Revert Back or Downgrade Domain Functional Level



Do this in certain circumstances that are explained below, we can do:

1 - Current Domain Functional Level should be Windows Server 2008 R2.
2 - Just can demote Domain Functional Level to Windows Server 2008.
3 - Should be Forest Functional Level on a Windows 2000 or 2003 or 2008. 
4 - We use Powershell command Set-ADDomainMode. 
(This is in Active Directory module for Windows PowerShell)
5 - Format command is as follows:

Set-ADDomainMode <Domain FQDN> -DomainMode Windows2008Doman

In this example Woodgrovebank.com is Domain FQDN.

Figure-7 below before the operation, as you see Domain Functional Level is 
on Windows Server 2008 R2.

Figure-7


Now we run the following command and then pressing Enter, type in the word Y 
and the Enter key again (Figure-8) 

SetADDomain Mode Woodgrovebank.com -DomainMode Windows2008Domain

Figure-8


That was done and now we check Domain Functional Level (Figur-9).

Figure-9


Open Diagnostics ---> Event Viewer, and check Directory Services.

You have an Event ID number: 2039, with description New Domain Functional Level 
is 3 (Figure-10)

Figure-10



Never forget, Revert back first Forest Functional Level, 
then Domain Functional Level.


AD-Powershell for Active Directory Administrators
Move (Transfering or Seizing) FSMO roles with AD-Powershell command to another Domain Controller