Front-end DNS that falls back to authoritative servers?

I've got a domain registered and hosted at a commercial site that provides DNS. Everything works fine.

On my LAN are a number of machines that I'd like to have local DNS data for but not have that visible beyond my local network. Ie:

local_server_1 IN A 192.168.1.100
local_server_2 IN A 192.168.1.111
nas IN A 192.168.1.200

Is there a way to have a local DNS that all my machines point to by default which will resolve all the local addresses, but if not found, then fall back to the authoritative server at my ISP? Ie, if I query for local_server_1.mydomain.com then the local box returns 192.168.1.100 but my web server www... is not in the local DNS so it'll look it up at the real server and then returns the real (public) address of that server.

For obvious reasons I don't want to manually copy the entries from the main server since my ISP might change my IP addresses to suit their network, but I don't want to incldue my internal addresses in their database either.

Is there a way to do this?

Thanks

Bob

Hello Bob,

If you are going to use the same internal and external domain name, then the design is called split-DNS. What you would have to do on your internal zone is have your internal records and external records. On the external zone (the one you have hosted by your registrar) you would only have the external records. There is no way around this because your internal DNS servers are also authoritative. If they receive a query for that domain name, they will NOT go out anywhere else to search for an answer if they do not have it.

Now, if your internal and external domain names are different, say corp.local and corp.com, then there is no need to have the external records stored on your internal zone. Your internal DNS servers will contain the external DNS servers to get the answer for corp.com when they receive a query for that domain.

I know its not what you wanted to hear, but that is how DNS works.

Hope the information helps... more info on this topic: http://itgeared.com/what-is-split-b...plit-horizon-or