OS X

Step 1

First you'll need to set up DNS for the domain names within your own network. Apple's instructions for setting up DNS on OS X Server can be found in the following places:

• On Apple's site: Mac OS X Server (v10.3 or Later): Network Services Administration (Manual).
• Archived here in case Apple ever decides to remove it from their site.

There are basically two ways to configure DNS on OS X Server:

1. Through the OS X graphical user interface by following the instructions starting on page 21 under "Managing DNS Service."
2. By editing the BIND config files. Instructions for this can be found starting on page 37 under See "Configuring BIND Using the Command Line".

I found that route 2 worked for me.

Step 2

After you've followed the steps above, set up your DNS Server to use ISP's name server to query domains that not defined in your DNS settings.

Open /etc/named.conf.

In the options directive, insert the following lines:

forwarders {
    123.456.789.012;
    123.456.789.013;
    123.456.789.014;
    };
forward only;
listen-on {127.0.0.1; 10.3.2.1; };

The forwarders option contains your ISP's name server IP address. Listen-on contains the loopback and the DNS server's IP address.