Chapter 36 Content Filtering
ZyWALL/USG Series User’s Guide
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Figure 447 Content Filter Lookup Procedure
1 A computer behind the ZyWALL/USG tries to access a web site.
2 The ZyWALL/USG looks up the web site in its cache. If an attempt to access the web site was made
in the past, a record of that web site’s category will be in the ZyWALL/USG’s cache. The ZyWALL/
USG blocks, blocks and logs or just logs the request based on your configuration.
3 Use the Content Filter Cache screen to configure how long a web site address remains in the
cache as well as view those web site addresses. All of the web site address records are also cleared
from the local cache when the ZyWALL/USG restarts.
4 If the ZyWALL/USG has no record of the web site, it queries the external content filter database and
simultaneously sends the request to the web server.
5 The external content filter server sends the category information back to the ZyWALL/USG, which
then blocks and/or logs access to the web site based on the settings in the content filter profile. The
web site’s address and category are then stored in the ZyWALL/USG’s content filter cache.
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