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The OUCS WWW Caching Proxy: how old is the information held in the Cache?


The cache server software aims for a reasonable compromise between ensuring that a document is up-to-date, and providing a cached copy. The question is, how can you be sure that the information you are looking out is up-do-date, or has it has been sitting in the local cache for several days?

There isn't a single answer to this, but the following items may help:

The following diagram shows the freshness algorithm used by Squid (thanks to Kolics Berthold):

Figure refresh-flowchart.gif [Squid freshness flowchart]