The network I currently manage will shortly be expanding to cover two sites, and due to the organisation of the company, I have already determined that a site-to-site hardware VPN will be implemented to link the two sites. The WAN link between the two will be between 20-100mb so no issues with bandwidth for AD/DFS etc. replication.

I will also likely be looking at installing a single Active Directory domain across both HQ and branch office, as I understand that modern day Microsoft best practices recommend steering away from multiple domains in a single forest except in exceptional circumstances.

My question is this...

If I maintain one domain across both sites (say company.com), how can I maintain a logical DNS separation between the two sites, (say for arguments sake dc1.london.company.com and dc1.birmingham.company.com)? Can this be done by structuring DNS in a certain way, without having to have a london.company.com and birmingham.company.com AD domain, one for each site?

Thank you in advance for any advice that can point me in the right direction!

1 Answer 1


You don't have different DNS namespaces for the two branches if they're in the same AD domain. There's no reason to. They would both be in the same DNS namespace as the parent. What reason would you have for two different DNS namespaces?

Also, avoid naming your AD domain "company.com" if that's also what your external website's name is. Name it something like "ad.company.com" or "internal.company.com". Having a split namespace will cause headaches.

  • Thanks for your comment. I am aware that they would both be in the same DNS namespace. I think you misunderstood my question, which is: how would it be possible to have some form of logical, organisational DNS separation between the two sites, without having DNS physically appear separate? i.e. server.site1.company.com and server.site2.company.com. Surely it is recommended that there is at least some organisational separation in DNS between the two sites?
    – George
    Jan 26, 2013 at 0:20
  • No, you're misunderstanding. They would all be in the same zone. This is common. If you want some kind of visual separation, prefix the servers and workstations at each site with something like USA- for the region. So Fileserver-01 would be USA-Fileserver-01 if it were in the United States site. Why do you want subdomains for each site in the same domain? Just for the look? It doesn't serve a purpose.
    – MDMarra
    Jan 26, 2013 at 0:32
  • 1
    +1 for intelligent DNS design. ;)
    – Ryan Ries
    Jan 26, 2013 at 1:02
  • OK, thanks, I'm with you. One final, brief question if I may... you mention a subdomain for internal DNS - e.g. ad.company.com. I understand in this scenario, users would have to enter the rather meaningless down-level/NetBIOS domain name during logon of AD\joe.bloggs. Is there any way - similar to configuring a custom UPN in AD Domains/Trusts - to change this so users have a more meaningful login domain of COMPANY\joe.bloggs? Thanks.
    – George
    Jan 26, 2013 at 15:11
  • 1
    You can set the domain's NETBIOS name to whatever you want when you're promoting the first DC in the domain. Just select "Advanced Installation"
    – MDMarra
    Jan 26, 2013 at 17:52

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