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I'm helping a (devops) client move their technology stack (VMware, Windows AD, Ubuntu Linux) from their old co-location facility to a new environment. Rather than move the hardware and systems outright, I've built a parallel environment in the new data center...

One thing I need to establish in the new site is Active Directory. There's an existing AD comprised of a single domain controller at their old site (2008 R2). While the new facility has a Cisco ASA firewall, their old site does not. Their current systems are exposed to the web with no firewalling; including the domain controller! A site-to-site VPN tunnel does not seem to be an option.

I'd like to build another domain controller at the new site; basically joining a domain over the internet. This is necessary for the VMware Virtual Center, DNS and a few other things I need to proceed with the new environment. I built a new Windows 2008 R2 server and took the following steps:

  • Successfully joined it to the domain (over the internet, limiting the new site to the old site's source addresses).
  • Added a new AD site for the old and new subnets (they're different).
  • Verified what I could of DNS.
  • Installed the AD binaries.
  • Ran dcpromo under a domain Administrator account.

The dcpromo step fails a few minutes into the process with:

The operation failed because:

Active Directory Domain Services could not create the NTDS Settings object for this Active Directory Domain Controller CN=NTDS Settings,CN=DC2,CN=Servers,CN=ServerCentral,CN=Sites,CN=Configuration,DC=hire-a-sysadmin,DC=com on the remote AD DC PEDC.hire-a-sysadmin.com. Ensure the provided network credentials have sufficient permissions.

"The RPC server is unavailable."

I did notice that the old domain controller I'm trying to replicate from is multi-homed. Since the client does not have a firewall at their old co-location site, their servers all seem to have public IPs and default gateways that point to the web, and a second interface slated for internal communication on a 10.10.10.0/24 subnet. I could see that being an issue, as it just seems like a bad practice.

How can I complete the dcpromo process on this new domain controller?

Edit - I ran Port Query, as recommended below. The only port with a non-zero status was port 42 - TCP port 42 (nameserver service): NOT LISTENING. I believe that's only for WINS resolution.

  • can you post the asa congfig? – user1008764 May 6 '13 at 12:17
  • @user1008764 No. What are you suggesting? – ewwhite May 6 '13 at 12:20
  • I'd go with the firewall blocking an important port. Run through the steps here, it may provide clues: blogs.technet.com/b/abizerh/archive/2009/06/11/… – James Hebden May 6 '13 at 12:28
  • @JamesHebden All of IP is allowed on the Cisco from the source DC to the new DC. – ewwhite May 6 '13 at 12:29
  • Is there any NAT involved, or does the new DC have a public IP? – James Hebden May 6 '13 at 12:44
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As janky as this is, I ended up establishing a Cisco client VPN from the old DC to the new datacenter's ASA firewall. This allowed replication and the dcpromo to complete.

  • Oh, @MDMarra You made the problem worse! – ewwhite May 7 '13 at 20:47

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