Windows – How to have Windows Server DNS use hosts file to resolve specific host names

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[NOTE: The solution of this question is perfect, by something stray away from what the title indicates.]

I'm facing a small problem with Windows Server 2003 DNS service. In my corporation, I'm running Microsoft DNS server(172.16.0.12) to do name resolution to my company intranet(domain name ends in dev.nls. resolving to IP 172.16..), and it is also configured as a DNS forwarder to forward other domain names(e.g. *.google.com , *.sf.net) to Internet real DNS servers. This internal DNS server never tends to serve users from outside world.

And, we are running a mail server(serving incoming mail for a real Internet domain @nlscan.com) inside company firewall which can be accessed in either way:

  1. by connecting to 172.16.0.10 from within intranet.
  2. by connecting to mail.nlscan.com(resolved to 202.101.116.9) from Internet.

Note that 172.16.0.10 and 202.101.116.9 is not the same physical machine. The 202 one is a firewall machine who do port forwarding of port 25 and 110 to intranet address 172.16.0.10 .

Now my question: If users inside corporate LAN want to resolve mail.nlscan.com, it resolves to 202.101.116.9. That's correct and workable, BUT NOT GOOD, because the mail traffic goes to the firewall machine then bounces to 172.16.0.10 . I hope that our internal DNS server can intercept the name mail.nlscan.com and resolve it to 172.16.0.10 . So, I hope that I can write an entry in "hosts" file on 172.16.0.12 to do this. But, how can Microsoft DNS server recognize this "hosts" file?

Maybe you suggest, why not have intranet user use 172.16.0.10 to access my mail server? I have to say it is inconvenient, suppose a user(employee) works on his laptop, daytime in office and nighttime at home. When he is at home, he cannot use 172.16.0.10.

Creating a zone for nlscan.com on our internal DNS server is not feasible, because the name server for nlscan.com domain is on our ISP, and it is responsible for resolving other host names and sub-domains under nlscan.com.

[EDIT]

As WesleyDavid suggested, I follow the solution of simply create a zone named mailserver.nlscan.com and place a nameless A record in that zone . Time proves this works well.

Best Answer

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?

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