CFS Category 100

If the CFS rating lookup process cannot be done, you may see web site access attempts blocked due to ‘category 100’:

01/01/2009 08:43:07.624 Web site access denied 10.16.38.42, 1980, LAN 157.166.226.26, 80, WAN Category:100...

Content Filter Service Category 100 means "Connection problem on firewall", which inhibits the ability of the service to get a rating for the site. This can happen on firewalls with a slow or problematic internet connection, or the inability to resolve the CFS servers via DNS.

1.     A CFS rating check begins with a DNS lookup.  Check the DNS servers configured on the firewall (Network | DNS) to be sure they can resolve our CFS servers correctly:

2.     Go to System | Diagnostics and do a DNS Name Lookup on our CFS servers (webcfs00.global.sonicwall.com):

3.     If the DNS Name Lookup doesn’t resolve to an IP address, then your configured DNS servers are likely not reachable.  Try changing the primary DNS to 4.2.2.2 and test.  If it is successful, then investigate issues with your DNS servers.

4.     If the DNS Name Lookup resolved webcfs00.global.sonicwall.com, then the issue may be due to slow response.  Try raising the value at Security Services | Content Filter | Configure - ‘If server is unavailable for (seconds)’:

5.     If the name lookup is successful, but you are still seeing ‘Category 100’, try looking at a packet capture to see if the CFS servers are responding.  When a user browses to a webpage, the firewall will first do a DNS lookup on the CFS servers address.  Then the firewall sends a DNS query to the CFS server using a hex-encoded value for the website name:

In the capture above you can see that the firewall sent the DNS query to the CFS server, and in packet #2 the CFS server sent a response.