I added in a Windows server 2008 R2 box today and then once it was ready, went to promote it (via DCPROMO) to a DC. Unfortunately it came back with the error “To install a domain controller into this Active Directory Forest, you must first prepare the forest using “adprep /forestprep”
I followed the guide here but essentially, all you have to do is:
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Search on the 2K8 disk for ADPRP.exe and then copy the contents of the folder that is in to a new folder (c:\ADPREP) on your 2K3 box.
Turns out ADPREP is on the sk8 disk, just do a search for ADPREP.exe -
As my 2K3 box is 32bit, I couldn’t run ADPREP.exe, but luckily there is ADPREP32.exe in the same directory, this needs to be used instead.
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So on your Schema master, navigate to c:\ADPREP (or wherever u copied the files to) and run adprep32.exe /forest prep
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Then on your infrastructure master run adprep32.exe /domainprep /gpprep
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And then run adprep32.exe /domainprep
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And then finally run Adprep32.exe /rodcprep (Which adds in support for Read Only Doamin Controllers, a new feature in Server 2008.)
Then you can go ahead an DCPROMO your server 2008 box, job done.