All sub-domains to one IP in hosts file

The latter part of this post is wrong. I was under the impression, based on some stuff I had read on the web (if it's on the web, it must be true!) that part of the Windows DNS Server Service's tasks for creating its cache was to also load its host file into cache along with its local zone data. I searched around and couldn't find hard evidence of this. I tested the theory on my own Server 2008 R2 machine and found that the hosts file was not used to build the DNS Server's Cache.

However, I believe I have a slightly more elegant solution that Massimo. Instead of creating an authoritative zone for the entire nlscan.com zone, simply create a zone named mailserver.nlscan.com and place a nameless A record in that zone. The nameless A record will have the same name as the zone itself and you can give it the IP address that you want. All other domains underneath nlscan.com as well as nlscan.com itself will resolve by public DNS.

I just tested this out on my own Server 2008 R2 DNS server and was able to make my friend's website (nessus.nl) resolve via public DNS servers but the specific subdomain (blog.nessus.nl) resolve to an Apple.com IP address. Try it and see if it works for you.

Older, wrong post commences:

If my understanding is correct (EDIT: and it is not), when the DNS cache is built in the Server 2003 machine it pulls in entries from the hosts file as well as it's zone data. Placing 172.16.0.10 mailserver.nlscan.com in your Server 2003 machine's hosts file should solve the problem. Restart your DNS services after changing your hosts file.

Use ipconfig /displaydns on any Windows machine (specifically, your Server 2003 DNS machine) to see your host file entries. Also keep in mind that negative responses are cached in your clients so always run ipconfig /flushdns on the clients that you're experimenting with. Otherwise you'll end up abusing yourself against various hard objects as you wonder why your clients can't resolve a name you just entered into a zone / hosts file. =)

Have you tried this and failed?

For exchange to ping AD, it will need to go out the host adapter, and then back in the host adapter (or the other host adapter, since you have two on the same subnet, and I'm not sure which one is bound to which). Try disabling the windows firewall on the host (or heck, all 3) then, if that works, start adding back the rules till you find the one that's causing the issue.

Also, you have a couple of VMWare and a couple of VBOX adapters on your host.. if you have a bunch of other VM's using nat, that's probably fine, but running both VMWare and VBox at the same time is going to cause resource conflicts..