3Com SUPERSTACK 3 WEBCACHE 3000, User Manual

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Web Caching Overview 31
between the client machines and the origin Web servers. The Webcache
then intercepts and serves requests from the client machines for Web
content in the following way:
1 A URL is entered into a Web browser by a user on a client machine in
your network.
2 The Webcache receives the request for the URL from the client machine
and checks its cache for the requested content.
3 If the content is already in the cache and is current enough to serve
(see
“Current and Expired Content” on page 32 ), the Webcache
immediately serves it to the client machine. This is a cache hit , as shown
in Figure 2 .
Figure 2 A Cache Hit
4 If the content is not in the cache or the content is expired (see “Current
and Expired Content” on page 32 ), the Webcache connects to the origin
Web server and retrieves the content. This is a cache miss , as shown in
Figure 3 . The content is then simultaneously served to the client machine
and stored in the cache. Subsequent requests for that content will be
served directly from the Webcache.
Figure 3 A Cache Miss
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