In the community today, it came up that ISA 2004, when installed in a clean install, doesn't cache internet traffic. This is by design.
ISA Server 2004 Web Caching in Windows SBS
By default, Internet Security and Acceleration (ISA) Server 2004 does not configure Web caching during installation. The Windows SBS team decided to not enable Web caching during installation for these reasons:
- Web caching is most beneficial in an enterprise environment, which can have thousands of requests to the same sites. An enterprise can potentially save time and bandwidth by caching these sites locally and refreshing them periodically. Web caching is not as beneficial to a small business because of the lower number of duplicate requests. In fact, Web caching can cause a small business to use more bandwidth because it periodically refreshes the cached sites.
- Configuring the cache rules for ISA Server 2004 requires additional administrative overhead from the small business. To operate at maximum efficiency, the cache rules need to be configured by an experienced administrator who is familiar with the network traffic patterns of the particular site.