Yesterday I experienced an interesting problem when attempting to run DCPROMO on a new Server 2008 Enterprise SP-2 to promote a server to become a domain controller in a Server 2000/2003 environment. Every time I ran DCPROMO on the 2008 box, it kept errorring out stating that I first needed to run ADPREP. However, I had already run it on the 2003 AD Server:
To install a domain controller into this Active Directory forest, you must first perpare the forest using “adprep/forestprep”. The Adprep utility is available on the Windows Server 2008 installation media in the Windows\sources\adprep folder
I’ve upgraded many domains from 2000 and 2003 to a 2008 domain, and don’t recall running into this problem before.
As a toubleshooting steps:
- I knew that you must upgrade all Server 2000 domain controllers to at least SP-2 or apply a specific hotfix. A quick double-check of our 2000 box showed that we were at SP-4 and tha patch was unneeded.
- I also decided to verify the forst and domain functional levels, which were also set to 2000 native.
- Since we were still failing, a quick knowledgebase check did not reveal anything, and this new 2008 server was going to be replacing our 2000 server, I decided to simply remove any problem with the 2000 box from the equation. I double checked that it was not holding any FSMO roles, or any other AD integrated services which existed only on that box (DNS, DHCP, IAS, CA, etc)
- After demoting the 2000 server, I also upgraded the forset and domain functional level to 2003 native, but this also did not resolve the problem.
- I began to run a series of DSUtil commands to check the DNS and overall domain and everything cameback successfull… except when I ran the utility on the 2008 server. But since the utlity came back fine on the 2003 box, I assumed there must be something wrong onthe 2008 box itself.
- I double checked that all patches were applied to the 2003 and 2008 boxes
- I then researched the issue more widely on the internet via Google. A couple of things came up which were misses, but probable causes for other networks, so I’ll list them here:
- In multi-domain forests, be sure to prep both the forest and domain controllers
- Make sure you run adprep on the box which contains your Schema Master FSMO
- Make sure you have proper DNS connectivity both ways on current and additional domain controller (add static entries for forward lookups as needed)
- Ensure DNS is Active Directory aware (yes, you can install in non-aware environments but have to manually create the DNS entries, which can cause problems with an automated DC promo).
- Make sure you disable third party firewalls
The last entry caught my eye and while we were not running any firewalls or anti-virus on the server yet, in 2008 SP-2 after installing the server the next automatic step was to enable the Windows Firewall. How you would assume that DCPromo would know about and could create the proper holes in the firewall to permit DCPromo to work, but apparently it does not. At least not in SP-2. So disable Windows Firewall while performing the DCPromo and it completes without problem. Then reable as you see fit. I don’t recall this problem or a need to do this in pre-SP-2 2008 server DCPromo’s, nor is it listed under any Microsoft documentation for performing a DCPromo, so it sounds like another excellent undocumented feature.