Raise AD forest funcation level effect lower version of OS

Question

Our forest and domain funcational level is 2008 R2 and Exchange 2010 is running on Windows 2008 R2. We have to raise our forest and domain funcational level to Windows 2012 R2.

My concern, the servers that are running on Windows 2008 R2 and Exchange 2010 will be connected on DC 2012 R2 after upgrading the forest and domain level, not talking about the DC 2008 R2.

Please confirm.

Answer 1

Hi @Innocent Heartvoice ,

Exchange 2010 is supported with Windows Server 2012 R2 AD servers and AD forest functional level of 2012 R2, as long as your Exchange 2010 is running SP3 RU5 - RU21.

There shouldn't be any effect on your Exchange when upgrading your AD forest functional level to 2012 R2.

For more information, see:

Exchange Server supportability matrix
https://learn.microsoft.com/en-us/Exchange/plan-and-deploy/supportability-matrix?redirectedfrom=MSDN&view=exchserver-2019

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Best regards,
Leon

Answer 2

Hello @Innocent Heartvoice ,

Thank you for posting here.

Hope the information provided by LeonLaude is helpful to you.

Here is another information for your reference.

Functional levels determine the available Active Directory Domain Services (AD DS) domain or forest capabilities. They also determine which Windows Server operating systems you can run on domain controllers in the domain or forest. However, functional levels do not affect which operating systems you can run on workstations and member servers that are joined to the domain or forest.

And before you raise your forest and domain functional level to Windows 2012 R2, ensure all the Domain Controllers in the forest are 2012 R2 DCs.

Reference
Forest and Domain Functional Levels
https://learn.microsoft.com/en-us/windows-server/identity/ad-ds/active-directory-functional-levels

If anything is unclear or should you have any question or concern, please feel free to let us know.

Best Regards,
Daisy Zhou

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