How Web Caching Works With A User's Local Cache - Nortel BayStack Instant Internet 100-S Using Manual

Before the Instant Internet unit sends requested Web content to the user, it
evaluates each Web entry and then does one of two things:
• If the entry is not already in the cache, the cache server retrieves the entry
from the originating Web server, caches it, and then sends the entry to the
user.
• If the entry is in the cache, the cache server evaluates the date and time of the
entry and then does one of the following:
— If the entry in the cache is still fresh, the cache server sends the entry in
the cache to the user.
— If the entry in the cache is expired, the cache server sends a conditional
request to the originating Web server. If the data on the server has
changed, it replaces the cached entry with the new entry from the
originating Web server, and then sends the new entry to the user.

How Web caching works with a user's local cache

As a downstream caching proxy server, the Instant Internet unit is located between
a user's workstation on the network and the Internet. If you disable the local cache
on a user's Web browser, the Instant Internet unit is the user's primary cache and
all requests for Web content go directly to the cache server. If you enable the local
cache, the cache server is a secondary cache. Requests for Web content are
directed first to the user's local cache, and then to the Instant Internet unit.
Although using the Instant Internet unit as the only cache slightly increases traffic
on your local network, doing so provides several advantages. This setup:
• Frees up hard disk space on each user's workstation by eliminating the need to
reserve space for caching.
• Increases the number of entries in the cache that are available to all users.
• Increases cache statistics because all requests for Web content pass through
the Instant Internet unit which gives the truest measure of the efficiency of the
cache.
Using the BayStack Instant Internet Management Software Version 7.11
Chapter 7 Web cache configuration 203