We are running a research project with hundreds (becoming thousands) of remote hosts. Each host is running OpenVPN so we can find them regardless of what their 'assigned' IP is. We have been using DynDNS to manage this but we're running into some issues with them ( API is weak/nonexistent, size constraints, etc).

Im looking into setting up a internal-only domain (EG "our.stuff" so a host would be "site1.our.stuff" or "site3.net4.our.stuff") that I can configure with the info from the OpenVPN server.

Since we'd have to point our internal DNS to this machine it would have to be able to route/cache requests for 'external' machines as well. I've been trying to read about 'internal DNS', 'private', 'non-routeable' but I'm not having much success.

Summary: need info on internal, caching DNS server. Something with open-source would be ideal. If not, I can script out changes to .conf, etc.