I can not ping/resolve DNS recored

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http://serverfault.com – I set up an internet lab with 3GNS , 3 routers , in each node there is a computer connected. one of the host is a DNS server , server 2003. The other one is an XP machine. Ping is good between routers and machines but no ability to ping domain.com record on DNS server 2003. I set a static nat on the router to route all traffic form gateway to the DNS server internal ip address, still no answer for the dns recored. Any ideas or thoughts will be most welcome. Thanks (HowTos)