Question : Can we able to resovle internet with out  haveing  a  public dns server inside the lan network

Hi ,
i have a setup here in my office. i will get internet from my ISP  connected to my WAN Router and that is connected to a PIX
   ISP(INTERNET)>>>>>WAN ROUTER(CISCO)>>>>>>CISCO PIX>>>>>> LAN SEGMENT   this is the way it is connected.
and domain environment is windows 2008 and has a DC & ADC. DC& ADC has both internal DNS & DHCP configured.
Along with this DNS configured on DC & ADC i have another DNS configured on ISA2000 server. In this ISA server 2000 DNS is configured in such a way that it will resolve all our internet traffic. ISA 2000 is deployed as a proxy and webcahe server. Here now we are going to use Websense in  place of ISA2000. and i dont want to give any of the public dns values   inside my lan network. every thing(Public dns) will be configured in the pix and router. For resolving the internet for my end users automatically my internal DNS servers(my DC& ADC) should be able to resolve the public DNS and resolve the user request (webpages or URL). Please help me out to so as i am stuck here.

Answer : Can we able to resovle internet with out  haveing  a  public dns server inside the lan network

Here are some references from Microsoft.

Configure a DNS server to use forwarders:
http://technet.microsoft.com/en-us/library/cc773370(WS.10).aspx

Using forwarders:
http://technet.microsoft.com/en-us/library/cc757172(WS.10).aspx

Here are some instructions:
+Open DNS Management Tool
+Right-click and select properties of server
+Click on forwarders tab and make an entry for "All other DNS domains" as shown with valid IP addresses of your ISP DNS servers.

DNSFwdrs.jpg (34 KB) (File Type Details) 

Example DNS Forwarders