Exchange 2010 SP3 Rollup 5 Added Support for Windows Server 2012 R2 Active Directory

6 weeks ago (February 25th 2014) Microsoft finally took away the last barrier to upgrading some of our Windows Server 2012 Active Directory Environments to R2.  Most of them are still running Exchange 2010 SP3 and not Exchange 2013. The reason is that Exchange 2013 was not deployed is whole other discussion Eye rolling smile.

However that dis mean that until the release of  Exchange Server 2010 SP3 Update Rollup 5 last month we could not upgrade Active Directory to Windows Server 2012 R2. Rollup 5 brought us support for exactly that. We can now:

  • Support Domain Controllers running Windows Server 2012 R2
  • Raise the Active Directory Forest Function Level and Domain Functional Level to Windows Server 2012 R2

Please note that you cannot deploy Exchange Server 2010 (SP3 RU5) on Windows Server 2012 R2 and you’ll probably never will be able to do that. I’m not sure Microsoft has any plans for this.

Now our office moves have been concluded, meaning I can get back to IT Infrastructure instead of being an glorified logistics & facility peon, we’re doing the upgrade.

This also means we can move the Active Directory environments to the latest version so we have the best possible position for any future IT projects at very low risk. The environments are already at W2K12 functional level. If the budgets get so tight they lose/scrap EA or volume licensing it also allows them to run at this level for many years to come without causing any blocking issues.

Reverting the Forest & Domain Functional Levels in Window Server 2008 R2, 2012, 2012 R2

Since Windows Server 2008 R2 and now with Windows Server 2012(R2)you can roll back the domain and forest functional level under certain conditions. This was not possible before with previous versions of Windows. In these cases you would have to revert to a restore from backup. Yup pretty hefty so raising functional levels has to be done with care.

Now this isn’t a free fire zone there are some conditions as listed in the table below.

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So you cannot have advanced features like the AD recycle bin enabled in some conditions. Enabling this is irreversible, so you cannot revert the Forest Functional Level of your environment to a level that supports the AD recycle bin when it has been enabled. Today that means from Windows Server 2012(R2) to Windows Server 2008 R2.

You also need Enterprise Administrator rights to do so, which I hope you’ll understand. It’s also a Windows PowerShell only feature (Set-ADDomainMode).

I used this information recently during an upgrade of an Windows Server 2008 R2 domain to Windows Server 2012 where they wanted to raise the domain and forest functional level. As they had a Forest Trust between the (now) Windows Server 2012 forest/domain and another Windows Server 2008 R2 forest/domain. They had enabled the Recycle Bin when still at Windows 2008 R2. They wanted to know if they would have issues with the trust and if so whether they could revert the levels in that case.

Well I could put their mind at ease. Look at the table. Yes you can go back to Windows 2008 R2 Forest Functional level as that’s a version that also supports AD Recycle bin so it doesn’t matter that is enabled.  And no, the forest trust capability is not affected by the forest functional level in this case as all you need there is to be at a minimum level of Windows 2003 to be able to do a forest trust. Forest Trust is enabled from and above Windows Server 2003 Forest functional Level. In a Windows Server 2000 Forest functional Level, Forest Trust is disabled. That means you can do them between forests at different functional levels a long as non of them is lower than Windows 2003. In this case it’s Windows 2008 R2 that’s the lowest, so again, not an issue.

How? Very simple:

Set-ADDomain Mode mydomain.com -DomainMode Windows2008R2Domain

Set-ADForestMode mydomain.com -ForestMode Windows2008R2Forest

Take a look at these TechNet Resources Understanding Active Directory Domain Services (AD DS) Functional Levels  and Set-ADDomainMode for more information.