Can I add windows 2008 sp2 domain controller to a domain with forest functional level Windows 2008 R2?

Can I add windows 2008 sp2 domain controller to a domain with forest functional level Windows 2008 R2?

We recently set the FFL to Windows 2008 R2, but now have discovered that an app needs a Windows 2008 SP2 domain controller, that we just took down. 

Can I add that Windows 2008 SP2 domain controller back into a domain now set at Windows 2008 R2?

I would upgrade that DC to Windows 2008 R2 before adding it to the domain, but its a VMware virtual server and previous attempts to upgrade out virtual DC's to Windows 2008 R2 and resulted in crashed servers.

June 23rd, 2015 9:29am

Windows Server 2008 R2

Forest functional level Available features Supported domain controllers

All domains that are subsequently added to the forest will operate at theWindows Server 2008 R2 domain functional level by default.

If you plan to include only domain controllers that run Windows Server 2008 R2 in the entire forest, you might choose this forest functional level for administrative convenience. If you do, you will never have to raise the domain functional level for each domain that you create in the forest.

  • Windows Server 2012 R2
  • Windows Server 2012
  • Windows Server 2008 R2
https://technet.microsoft.com/en-us/library/understanding-active-directory-functional-levels%28v=ws.10%29.aspx?f=255&MSPPError=-2147217396
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June 23rd, 2015 10:19am

Also

After you set the forest functional level to a certain value, you cannot roll back or lower the forest functional level, with the following exception: after you raise the forest functional level to Windows Server 2012, you can lower it to Windows Server 2008 R2. If Active Directory Recycle Bin has not been enabled, you can also lower the forest functional level from Windows Server 2012 back to Windows Server 2008 R2 or Windows Server 2008 or from Windows Server 2008 R2 back to Windows Server 2008. If the forest functional level is set to Windows Server 2008 R2, it cannot be rolled back, for example, to Windows Server 2003. For more information, see Understanding Active Directory Domain Services (AD DS) Functional Levels.

https://technet.microsoft.com/en-us/library/cc730985.aspx

June 23rd, 2015 10:25am

FFLs and DFLs add features, how come an application that works with a 2008 DC cannot work with a 2
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June 23rd, 2015 10:54am

Hi Galloway,

Thanks for your post.

There is no problem to have mixed OS DC environments. However, if you have a higher functional level in the domain/forest than the DC you want to promote. Then it is not recommended to install since it may affect the active directory.

As some applications require specific DC versions. Therefore you have to check the compatibility, if required.

Best Regards,

Mary Dong

June 24th, 2015 2:59am

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