I'm looking at adding two Windows Server 2008 R2 Domain Controllers into our Windows Server 2003 domain to support our Exchange 2003 SP2 server and replace a retiring Windows Server 2003 Server.

Our Domain and Forest functional levels are currently Windows Server 2003, which supports domain controller operating systems (Windows Server 2008 R2, Windows Server 2008 and Windows Server 2003) according to the "Appendix of Functional Level Features" on Technet .

So there should not be an issue other than running adprep /forestprep and adprep /domain.... right!?

But, according to the Exchange Server Supportability Matrix, Windows Server 2008 R2 Active Directory Servers are not supported as global catalog servers or domain controllers in a Exchange 2003 SP2 environment!!!???

This was a shock to me... How can Windows Server 2008 R2 be a DC for a Windows Server 2003 domain and forest, but not communicate with an Exchange 2003 SP2 server?

Hopefully, I'm not the first to see this issue (or maybe I am), but I know a lot of Exchange 2003 admins will not be happy if there is not a work around... or is Microsoft trying to push everyone automatically to Exchange 2010...

  • The reason you’re probably running 2008R2 servers in an AD 2003 functional domain level is because you can’t upgrade to 2008R@ domain functional level and expect exchange 2003SP2 to functional. I've had this problem for months now and not one persona can solve it (looks like Microsoft really screwed up this time) my exchange server only recognizes the last 2003 AD server in the domain for "Directory access" it cannot/will not discover any of the 2008R2 AD servers (all FSMO roles, GC, DNS and DHCP are running on 2008R2 server. This is really really really stupid.
    – user66818
    Jan 16, 2011 at 4:38

4 Answers 4


The page you linked states quite clearly that read only 2008/2008R2 domain controllers are not supported; standard (i.e. writable) DCs are supported.

It also states that 2008/2008R2 domain and forest functional levels are supported.

What is not supported is running Exchange 2003 on a 2008/2008R2 server.


Installing Server 2008 R2 as a domain controller makes changes to the AD schema, that results in problems with Exchange 2003 and 2007. Exchange 2007 SP2 will resolve this issue to allow it to communicate with 2008 R2 DC's however as far as I am aware there is not update planned for Exchange 2003.

  • Nor is it needed, accordingly to the linked Technet article...
    – Massimo
    Apr 21, 2010 at 7:09

I read that matrix that you can use Win2008 DC's, just not move the domain to Win2008 native mode.

EDIT on April 22/2010: I believe the article has been changed by Microsoft since I answered; perhaps they have done more testing and have approved more configurations. So I read it as:

  • You can run Exchange 2003 on Win2003 only, not Win2008
  • Your AD environment can run on Win2008R2 domain controllers
  • Your AD forest level can be Win2008R2

However I have done none of this myself.

  • +!, Correct. Win2008R2 Servers are support. AD in 2008 Native Mode is not supported by Exchange prior to 2010 (IIRC). I am running an Exchange 2003 box against 2008 R2 DCs (in AD 2003 Functino Level).
    – Chris S
    Apr 19, 2010 at 13:31
  • This is not correct. The document says those levels are supported.
    – Massimo
    Apr 19, 2010 at 13:50
  • It's probably so; could you please update your answer accordingly? :-)
    – Massimo
    Apr 21, 2010 at 7:09

This Exchange Server Supportability Matrix link might be more helpful. There is clearly an X mark for Exchange 2003 SP2 running under all domain and forest levels up to and including Windows Server 2008 R2 Domain Functional Level and Windows Server 2008 R2 Forest Functional Level.

If it makes you feel any better, I am very much currently running Exchange 2003 SP2 (on Windows 2003) and Windows Server 2008 R2 DCs (with a domain and forest at 2003 level).

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