forwarders and another company's split dns

Kevin Darcy kcd at
Mon Jan 24 22:40:55 UTC 2005

srp336 at wrote:

>We have a sister company which has a split dns. They have an external
>server hosting their public dns records and also a private server on
>their LAN which, among other things, is being dynamically updated by
>Microsoft Active Directory. We'd like to be able to see those AD
>entries in their private name server. We have unrestricted access
>through a point-to-point T1 to that server.
>Is it possible to set our copy of bind to forward queries to that
>server as well as use the external name server for their domain (a
>domain which we don't host here)?
If they're running split dns "properly", then all of the external 
leaf-node entries in domains they also use internally, are duplicated in 
the internal versions of the relevant zones. You should verify that this 
is the case, and if it is, you should be able to forward that domain or 
those domains to their nameserver and both the internal and external 
name-resolution should work. Instead of forwarding, you might want to 
consider slave or stub zones.

If their internal DNS is completely disjoint from their external DNS 
(i.e. the external entries aren't copied), then life might be much 
harder. You should probably inquire how *their* clients sort things out, 
vis-a-vis accessing internal and external resources. Proxy magic? 
Routing magic? NAT? You might need to replicate some of that in your 

                                       - Kevin

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