I have a Windows Server 2008 R2 Server (Server A) running as a domain controller with Active Directory, Group Policy, and DNS services.

I set up a second Windows Server 2008 R2 server (Server B), added it to the domain, and installed the Active Directory, Group Policy, and DNS Roles.

If I take Server A offline, then Active Directory and Group policy services are no longer available on Server B.

What would I need to do in order keep AD & GPO services operating while one server or the other is offline?

[edit]: Would I possibly need to do something involving dcpromo.exe on Server B? If so, what might that be?

  • 1
    Did you enable the Global Catalog on the new server? technet.microsoft.com/en-us/library/cc758330%28v=ws.10%29.aspx – charlesbridge Jul 17 '13 at 16:49
  • I did not do so manually, however, when I looked, the "Global Catalog" option was checked for both servers. – Force Flow Jul 17 '13 at 16:53
  • Make sure that all domain clients are configured to use both DC/DNS servers for DNS. – joeqwerty Jul 17 '13 at 16:59
  • 1
    RE: your edit: Did you run DCPROMO on the new DC or did you just install the Roles? If you didn't run DCPROMO then you need to. Installing the Roles only installs the "bits". – joeqwerty Jul 17 '13 at 17:01
  • 1
    There are several ways to launch DCPROMO. Open an elevated command prompt and type DCPROMO then press the Enter key. Then follow the wizard. – joeqwerty Jul 17 '13 at 17:27

You need to run dcpromo on the second server to make it a domain controller and install the other roles.

You need to make sure it is a global catalog so that these services will continue to run if either server is offline. The AD content should replicate between the two servers by AD DS replication

  • Yeah, if you didn't actually run dcpromo, you don't have a second domain controller. – mfinni Jul 17 '13 at 17:16
  • After running DCPROMO from an elevated command prompt, each server was able to continue AD and GPO operations while the other was offline. – Force Flow Jul 17 '13 at 19:28


Ensure that each DC is a DNS server for the AD's DNS zone, and ensure that the DNS settings on each server's NIC points to itself and the other DNS server.

The order of which each should point to is a bit of a bone of contention, you can find people arguing both sides - but without both, when one is down, the other will be sunk.

Thus, also ensure that your client machines are configured to use both for DNS servers as well.

  • 2
    I've recently come to the conclusion (for my implementations) that each DC should point to another DC first for DNS and then to itself. – joeqwerty Jul 17 '13 at 16:52
  • Each server is configured as @joeqwerty describes. – Force Flow Jul 17 '13 at 16:54
  • As far as I can tell, there isn't a disruption in DNS resolution when one of the servers goes offline. – Force Flow Jul 17 '13 at 17:00
  • I like Joe's approach and it is the one that I use myself, but I've read both sides and wasn't going to try to be authoritative or exhaustive. – mfinni Jul 17 '13 at 17:17

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.