Question : Unable to re-add a 2003 domain controller after an OS reinstall

I had two Win 2003 domain controllers. Long story short, I recently had to reinstall the OS on one of them. Since I reinstalled the OS, whenever I try to re-add the server back to the domain, I receive an error stating that the domain controller already exists in Active Directory. Same results when I run dcpromo on it. I tried to delete it out of Active Directory so I could re-add it but I only receive the message stating that I need to run dcpromo to demote the domain controller before I can delete it. I obviously cannot run dcpromo on it to demote it since it isnt a domain controller anymore. I know I could just make up a new name for it but then I still have an extra domain controller in AD that doesnt exist.

Answer : Unable to re-add a 2003 domain controller after an OS reinstall

Take a look at this article on the NTFAQ. It outlined the process to remove a domain controller by hand. However if the server that you have rebuilt is already a member of the domain I would drop it out of the domain in to a workgroup. Wait at least 30 minutes for that change to replicate and delete the computer from ADUC.

http://www.windowsitpro.com/Article/ArticleID/13414/13414.html

After making the changes, wait 30 minutes again for those changes to be deleted before attempting to add the server back in to the domain and then dcpromo it in.

Simon.