200 CHAPTER 8 Deploying ISA Server 2006 as a Content Caching Server
Improving Web Access by Caching Content
The concept of content caching is not overly complex, and the key to its success lies in its
simplicity. Content caching works by saving local copies of web data on the hard drive of
the caching server and making that information available to the next clients that request
the same information from the same site.
The example shown in Figure 8.1 serves as an illustration: If Client1, configured to use
ISAServer1 as a proxy server, were to browse to the home page of www.microsoft.com and
www.cco.com, ISAServer1 would first check whether it had a recent local copy of the
websites accessed. If it did not, it would then initiate an HTTP request directly to the
www.cco.com and www.microsoft.com websites. When the websites return the text and
images associated with the site to ISAServer1, the server keeps a local copy and then
forwards the information back to the requesting Client1.
Later, Client2 requests information from the websites of www.cco.com and
www.samspublishing.com. The ISA server checks the local cache and finds that it
already has a recent copy of www.
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