Having a master domain controller running Windows 2003, and now I'd like to set up a new domain controller on a branch office. I really only have access to licenses for Windows 2008 R2 (through licensing.microsoft.com), so question is if a newly installed Windows 2008 Standard R2 can become a domain controller in the existing (2003) domain?

First I tried adprep /forestprep on the newly installed 2008, but it complained about not being a domain controller. I then tried dcpromo, but it too complained about it. According to MS documentation, it seems I have to run 'adprep /forestprep' on the master domain controller, and adprep is located in 2008 installation DVD.

Am I on the right track? Is the correct way to mount the 2008 installation dvd into the existing 2003 master controller, and run 'adprep /forestprep' on it there? Will I be able to run dcpromo on the 2008 once that has been completed?


  • Running adprep /forestprep and /domainprep on the primary domain controller results in: Forest-wide information has already been updated.
    – 3molo
    Jan 5, 2011 at 8:51

1 Answer 1


Yes, you are on the right track.

Put/Mount the 2008 DVD on the 2003 DC and run adprep (or adprep32) from there.

After this has been done you will then be able to DCPROMO the 2008 server.

  • It complains about it not being able to replicate all changes since last reboot, so no action is taken running adprep32. There's a secondary domain controller in "Users and computers" -> "Domain controllers" which is no longer available, and I removed it. Found it in 'sites and services' too, but right click and delete gave me this error message: ".... demote the controller using the Active Directory Installation wizard. If the domain controllers represented by these objects are permanently offline and can no longer be demoted ... you must delete them one at a time".
    – 3molo
    Jan 5, 2011 at 9:09
  • How do I find and delete these objects? I was not around when this old DS existed, all Im sure of is that it have not been around the last 6 months or so. So what ever is unique to that domain controller can safely be removed.
    – 3molo
    Jan 5, 2011 at 9:13
  • This article explains removing a failed DC quite nicely: petri.co.il/delete_failed_dcs_from_ad.htm After you have performed this, check over your DNS for any roque records relating to the old DC, DCdiag / Netdiag and check event viewer for any related errors
    – Ethos
    Jan 5, 2011 at 10:14

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