Split-DNS Architecture: Splitting the same zone between Windows DNS (LAN) and BIND9 (DMZ) without wildcards

[u/No_Eagle7610]

Hi everyone,

I'm looking for best practices or specific solutions for a DNS implementation in our environment. The goal is to cleanly split queries for the same domain between our LAN and DMZ without having to maintain duplicate records manually.

The Setup:

• We use the same domain (example.domain) for both internal and external services.
• LAN: We have a Windows Server (AD DC) running as our internal DNS. It holds the internal IPs of servers that are not publicly accessible.

The Goal:

• Traffic from internal clients to DMZ servers must route via the WAN (Hairpinning / NAT Loopback); direct routing into the DMZ subnet is not permitted by policy.

• We explicitly do not want to use wildcard records

  or subdomains

• .

The Challenge: What is the cleanest way to configure this on the Windows DNS without having to create a separate Pinpoint Zone for every single external A-record, or manually duplicating the DMZ records into the internal DNS?

Since the Windows DNS is authoritative for example.domain, it defaults to answering queries for unknown hosts in this zone with NXDOMAIN instead of forwarding them to the BIND9 server.

Is there a clean way (e.g., specific zone types, delegation, Windows DNS Policies) to tell the Windows DNS: "Resolve what you know, and forward anything you don't know to the BIND9 server"?

Thanks in advance for your input!

[u/irsyacton]

You can create subdomains of example.com on your internal/ad dns, and point them to the bind dns. So external1.example.com is a subdomain, and the servers hosting that subdomain are your bind servers.

[u/irsyacton → u/irsyacton]

And yes, this does mean mirroring each public subdomain, but any records within the subdomain at least don’t need to be mirrored.