Cache Freshness

When first introduced to Web content caching, many network administrators assume that the object cache on an proxy server is basically the same as a browser's cache, which all users access when they click the Back button. The logical extension from this assumption is the fear that iChain Proxy Services will serve stale content that doesn't accurately reflect the fresh content on the origin Web server.

Actually, most time-sensitive Web content is flagged by Webmasters in such a way that it cannot become stale unless a caching system ignores the Webmaster's settings. The proxy server honors all flags that affect cache freshness, including Time to Expire, Don't Cache, and Must Revalidate directives.

In addition, the proxy server can be fine-tuned for cache freshness in the following ways:

• Accelerated checking of objects that have longer-than-desirable Time to Expire headers.
• Delayed checking of objects that have shorter-than-desirable Time to Expire headers.
• Checking objects for freshness that do not include Time to Expire headers.

This is administered at Configure > Tuning > Cache Freshness. For more information on configuring the iChain Proxy Services for cache freshness, see Managing Cache Freshness and Cache Freshness Dialog Box.