Thanks all for your help
Actually, I'm doing this testing so that I can implement the real ISA Server system for my company's server network.
ISA Server 2004 is running on Windows 2003
At my company's server network, all the IP addresses of the servers are public (not private addresses like what I'm testing).
And there is a problem I'm not so sure: some of you suggest that I type the command "route...", I wonder where I can type that command? It is because when I tried creating the relationship as "ROUTE" between the internal network and the external network, I saw that the internal network can connect to the external network and connect to the internet. And I guess I also have to do this action: adding a static route to the router, indicating the gateway that leads to the internal network. I'm not so sure if I have to specify this static route when using the ISA Server, or the ISA Server will automatically talk to the router. Anyway, I'm still testing on that.
Weekend coming so fast.
Have a nice weekend everyone