Ask the Expert

Demote Exchange from domain controller to member server

My Exchange 2003 server is also a domain controller because it was the first domain controller in Active Directory. With other domain controller's now installed, we want to demote Exchange from being a domain controller to just a member server.

We have already moved the catalog server function to a different domain controller. Referencing a document in Microsoft Knowledge Base, we think we just have to move Flexible Single Master of Operations (FSMO) roles and run DCPROMO.

We want to make sure we are not missing an important step though. Is it really that simple; no users will lose access to e-mail?

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Yes, you need to move the FSMO roles to another domain controller and then DCPROMO the machine to demote it from being a domain controller to simply a member server. You should have no problems.


Per a Microsoft KB article, demoting a domain controller/global catalog after Exchange Server is installed will cause issues and is not supported. Here is the relevant excerpt from the article:

"For example, if you install Exchange Server 2003 on a member server, do not use the DCPROMO tool to promote the server to a domain controller. Or, if you install Exchange Server 2003 on a domain controller, do not use the DCPROMO tool to demote the server to a member server. Changing the role of a server after you install Exchange Server 2003 may result in loss of some Exchange functionality and is not supported."
—Peter D.


Moving the FSMO roles will not help. If Exchange Server is running the domain controller (DC), then it is not supported to demote it unless you move all the mailboxes on that server to a different Exchange server. The drawback is that it will corrupt the metabase if you demote the DC.

So, the best practice is to:

  1. Move all the mailboxes and public folders to other Exchange servers.
  2. Proceed with the demotion.

—Athif K.


Do you have comments on this Ask the Expert Q&A? Let us know.

Related information from

  • Expert Advice: How can I demote the Exchange server to a member server?
  • Reference Center: Active Directory tips and resources
  • Reference Center: Exchange 2003 tips and resources
  • This was first published in March 2006

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