Can't access a website with the internal DNS

Our client is running Windows 2008 R2 as DC/DNS. Every thing works except they can’t access their website hosted by a
hosting company. They get "The webpage cannot be found". However, if they replace the internal DNS (192.168.1.3 that is also DC/DNS IP address) with
their ISP DNS, they can access the website. All inside computers with the internal DNS have this problem. They don't have the problem to access other
websites.

If I ping nyrp.org, the public IP is x.x.x.x. However, I can’t access the website using the IP x.x.x.x in any Internet computers (inside or outside).

What could be the problem?

Bob Lin, MVP, MCSE & CNE Networking, Internet, Routing, VPN Troubleshooting on

http://www.ChicagoTech.net

http://www.howtonetworking.com