Q. Can I add a Windows Server 2003 domain controller (DC) to a Windows 2000 Server domain?

A. If you have only Win2K Server DCs in a domain and attempt to run Dcpromo from a Windows 2003 server so that it can join the domain, the command will fail and the error message that the figure at http://www.windowsitpro.com/articles/images/install2003dcinto2000foresterror.gif shows will be displayed. Before you can make a Windows 2003 server a DC in an existing Win2K Server domain, you must run the forest and domain preparation utility--Adprep--which you can find in the i386 folder on the Windows 2003 CD-ROM--by running the commands

adprep /forestprepadprep /domainprep

Be aware that these commands alter the schema and configuration of your forest and domain--especially if you have Microsoft Exchange 2000 Server installed--which can cause problems with the Windows 2003 forest preparation. (I'll cover the steps you need to take to avoid such problems in an upcoming FAQ.)