A container page is the main page that a user accesses when visiting a website, but additional websites may be loaded within the main page. If the Log Container page only option is enabled in the URL filtering profile, only the main container page will be logged, not subsequent pages that may be loaded within the container page. Because URL filtering can potentially generate a lot of log entries, you may want to turn on this option, so log entries will only contain those URIs where the requested page file name matches the specific mime-types. The default set includes the following mime-types:
application/pdf application/soap+xml application/xhtml+xml text/html text/plain text/xml
If you have enabled the Log container page only option, there may not always be a correlated URL log entry for threats detected by antivirus or vulnerability protection.

Related Documentation