Slightly advanced DNS help
Help me out, geniuses; I'm still new to DNS. Using Windows 2003 AD
Here's what I want to do: re-direct certian websites from a specific domain to an internal webserver, and allow others to go on as normal. The example I'll use is Yahoo webmail: I want to allow www.yahoo.com and the rest of yahoo to work as normal, but redirect mail.yahoo.com to an internal website that has a warning about webmail access not being allowed. Follow this procedure for any other major webmail carriers - Earthlink, AOL, etc.
Problem is, if I create a new zone for yahoo.com and create an A-record for "webmail" giving it my internal webserver IP, then the rest of yahoo.com is unresolvable. Forwarders are setup using ISP's DNS servers, and I assumed since my DNS server won't be able to resolve www.yahoo.com that it would forward that request on to the ISP, but it isn't happening like that.
What's the right way to do this?