I have a client that without going into all the details of WHY they would like this, here's what we are trying to accomplish.
We have 6 branch offices connected back to one main office. All computers/Offices are using Active Directory servers back at the main office.
There are two AD servers that also host their DNS. What this customer would like to accomplish is the following.
If the main office makes a DNS request not in their local DNS zone, forward it out to ISP DNS servers.
If any branch server makes a DNS request not in their local DNS zone, forward it out to OpenDNS Servers.
Goal: not to add any more physical Servers (not a VM shop yet) and keep both servers available to the local office.
We cant have all forwarders point to either location, they'd like to split them based on source network.
Right now, I've done a lot of reading on this and it doesn't seem possible to accomplish what they would like to do with a Windows DNS server, but I wanted to toss it out to EE and see if someone has some trickery up their sleeve.
If we cannot find a solution this way, I am thinking that we will recommend they bring up a third DNS server and point the branch offices to that and have it forward to OpenDNS and leave the two main servers at the main office pointing to the ISP DNS.
Thanks for your time.