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Deploying Exchange Server on the parent domain controller

We have a domain controller forest with one parent and many children. I would like to implement Microsoft Exchange on the parent (root) domain controller, but allow the child domain controller users to access it. What do I need to do?

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ForestPrep is required prior to installing your first Exchange server. This is the process that adds to required schema extensions and makes changes in the configuration naming container in Active Directory.

Once you ForestPrep your root domain controller, you should then run DomainPrep per child domain. Running DomainPrep in your child domains allow you to utilize your root installation of Exchange Server.

In detail, DomainPrep is required for the Recipient Update Service (RUS), and creates groups and permissions necessary for Microsoft Exchange to work within your child domain.

In your child domains, the following requirements need to be met prior to running DomainPrep:

  1. ForestPrep needs to have been run in the forest.
  2. Allow enough time for the schema extensions, as described above, to replicate through the environment.
  3. The account you are using to run DomainPrep needs to be in the domain admin security group.


Is it possible to add the Exchange server to the child domain and have it reflect the parent domain/root domain email namespace (i.e., versus
—David M.


You can define the Recipient Update Service (RUS) as you desire. It can generate SMTP namespace for either or -- but you need to ensure the appropriate MX record/necessary configuration is complete for inbound email to be routable.

These images may help make this clearer:

Figure 1

Figure 2

Peter terSteeg, Deployment and Migration Expert

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

Related information from

  • Expert Advice: Installing Exchange in a child domain controller
  • Expert Advice: Troubleshooting RUS issues
  • Tip: When Exchange Server setup fails using /FORESTPREP
  • 11 tips in 11 minutes: Migrating from Exchange 5.5 to Exchange 2003
  • Learning Guide: Exchange migration
  • Reference Center: Exchange migration advice
  • This was first published in April 2006

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