Introduction

One of the most misunderstood, but most critical, issues relating to the installation and management of ISA Server 2006 firewalls is that of ISA Server 2006 client types. Some of these client types have a classic client/server relationship with the ISA Server. That is, the client makes a request for data from the server; the server subsequently performs the work of retrieving the data, and returning the data to the client. The client/server relationship is dependent on client software installed on the client computer that makes it possible to communicate with the particular services running on the server.

In the case of ISA Server, the client might request data in the form of a Web page on the Internet; the ISA Server would perform the work of retrieving the Web page and delivering it to the client. However, not all ISA Server 2006 clients have a classic client/server relationship with the firewall, and each client type accesses networks outside its own in a different fashion. Furthermore, some applications work with one ISA Server 2006 client type but not with another. It is critical to determine the ISA Server 2006 client type before you install and configure ISA Server 2006. Failure to implement the correct ISA Server 2006 client type can lead to the misconception that the firewall is not working correctly.