Possible Duplicate:
Overriding some DNS entries in BIND for internal networks
I have two bind servers. One is at my colo, the other is on my LAN. They both use the same dns zone, example.org I want my private lan to query first using my local server for example.org, and if it does not find the answer there go out to my colo's DNS server.
My colo DNS has all my public DNS info, and my lan has all my private DNS info.
Is this possible and how would I do it. I'm Running BIND9 in Ubuntu
No it is not possible. There can only be one (master) server responsible for a domain. And many slaves that "copy" the zone. But they can't differ.
As you probably have no complete control over the hosted DNS you can't use it as the master and do dynamic IP updates from you LAN clients.
So you can not solve that problem. But a similar problem. Use your local DNS as a sub-zone DNS e.g. locallan.example.org. And "glue" it to the hosted DNS.
To have something not the standard way - and without BIND - look a duplicate question: Overriding some DNS entries in BIND for internal networks