I have named a domain internally in my forward lookup zone in windows dns for my internal network. There is one prefix that i need for it to look up using the named external DNS (like google DNS I host many intranet sites/locations, but i dont host our public web server in house. The issue is that we use a CDN, so the IP is never static, and I cant define it with a A record.

For Example:

Forward Lookup Zone Defined for: Contoso.com
department1.contoso.com = 192.168.x.5  
department2.contoso.com = 192.168.x.6  
www.contoso.com = [dynamic ip that needs to be looked up by]
contoso.com = [dynamic ip that needs to be looked up by]

I am stumped.
If i dont define www at all, my dns lookup comes back without an ip

  • I'm thinking either delegation or conditional forwarders might work. Nov 7 '17 at 16:44
  • Just to be clear, both your internal active directory domain name and public web domain name are identically named, and you want to forward internal client dns requests for the public website domain to an external DNS server?
    – twconnell
    Nov 8 '17 at 11:32
  • no, local domain for AD is anotherdomain.local
    – Renet123
    Nov 19 '17 at 22:10

Your best solution to this problem is absolutely a conditional forwarder, although as someone pointed out above a delegation would probably work as well if your DC can route to it. Of course, if it can't you'd have bigger problems. Otherwise, just typical split-brain DNS scenario where you're answering most clients for what you have, but anything specifically to www.contoso.com you can forward to this other server.

With the contoso.com it gets a wee bit hairier for kind for the same reason the other commenter mentioned. Your AD domain is using this. If your domain were instead a subdomain such as 'ad.contoso.com' you could also simply use a CF here. That, of course, assumes your dept1/dept examples are correct and not like dept1.ad.contoso.com

If your servers are at least 2012 R2 I believe there is a new functionality for this: https://blogs.technet.microsoft.com/networking/2015/05/12/split-brain-dns-deployment-using-windows-dns-server-policies/

Hope this helps.

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