DNS setup for internal and external addresses

Hi All,

Senario
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I currently have a single external (WAN) IP address, with internal (LAN) clients behind a router which supplies NAT and DHCP services. We would like to run directory services and understand that a DNS server is required for our internal server addresses etc.

I’ve configured the Mac OS X 10.3.9 DNS server as per the notes on this site and Mac OS X Server 10.3 – Visual QuickPro Guide and all seems to be working fine for our internal address translation.

The client machines receive a DHCP address from the router and the DNS server address on the clients points to our newly set-up OS X DNS server. ip address 192.168.2.50. The DNS server is also pointing to itself for DNS in it’s network config in system prefs.

What I don’t understand is how the clients and server are able to resolve external address such as http://www.afp548.com. Not that I should be complaining, as this is all great.

But how are the external addresses being resolved?

As far as I can tell, at no time have I entered any external DNS server address for the server to be able to look-up external domain names.