The version of ISA Server supplied with SBS 2003 premium edition is functionally equivalent to the standard edition of ISA Server 2000 with Service Pack 1. Additionally, all patches published between the release of the Service Pack and SBS 2003 have also been integrated in this version. Some setup files have also been modified as compared to the standard version of ISA server.
The installation type of the ISA server depends on how the network is secured or is to be secured. The most common scenarios are the use of a firewall, a demilitarized zone (DMZ), or even a DMZ with two firewalls.
A firewall is equipped with two network cards. One connects to the Internet, and the other connects to the local network. Thus two separate physical networks are established. The firewall serves as a router for the clients and protects the local network against unauthorized access via various filter mechanisms...