Using DNS to point certain domains to certain IPs

i should clairfy.  my internal domain name is actually domainname.local.  So i created a new zone called domainname.com and added the Host "mail" in there.  now when i ping mail.domainname.com itll resolve to the internal IP but any other subdomains of domainname.com wont resolve.

Do you mean other hosts within domainname.com or hosts within sub-domains of domainname.com?

(www.domainname.com would be an example of another host within domainname.com, but www.sub.domainname.com would be a host within a sub-domain).

i want internal users who acccess mail.acme.com to use the internal IP address.  i want internal users who access ftp.acme.com www.acme.com hello.acme.com to use the public IP address.

Then I think it will require some manual setup:
How many additional hosts like ftp, www etc are there? If just a few then you could simply add extra host records for them within the newly created DNS forward lookup zone.

If it is loads, then an alternative strategy would be to add a line to the hosts file on every user's computers for mail.domainname.com and remove that new zone you just created on your internal DNS server.

It depends which is more work, but the easier option if you have a lot of users is probably just to add a few more host records to the DNS zone for those other servers. Your DNS forward lookup zone can have host records that point to IP addresses outside your LAN as well as inside.

The answer is:

Conditional forwarding, see link for an explanation.

http://support.microsoft.com/kb/304491

Good Luck,

dooleydog, please read all the comments, not just the original question.

The author of the question confirmed that he doesn't actually have a sub-domain, just wants to use an internal IP for one host while using the public IP addresses for all other hosts so conditional forwarding can't be used (IMHO).

I was afraid that I'd have to either alter the HOSTS file or manually enter A records.  Isn't there a way for me to create an acme.com zone and just add a mail A record pointing to my internal IP and have all other requests to acme.com use my forwarder that i've configured?

and once it has those IPs to automatically cache them into the zone?

Solution that I used was to have internal users acccess antoher URL.

Taking suggestions on how to give point value as no solution was given that solved the issue.

That's your call.

I tried damned hard to answer the question as you asked it, including clarifying some ambiguities in the question. Using another URL seems to me to not be within the constraints that you specified in the question.

Good luck.

Just for the record, a quick postscript on the CNAME suggestion:
This only works if recursion is allowed on the internal DNS server for the Forwarders - i.e. you must *not* tick the box that says "Do not use recursion for this domain". Otherwise the public DNS server is being asked to resolve the name pointed to by the CNAME record, which it cannot do.

If you don't want to allow recursion generally on forwarders then you can add a conditional forwarder just for your public Internet domain name and allow recursion on that, but disable recursion on the forwarder settings for "All other DNS domains".