Why is the block page sometimes blank?

In some cases, a very small, blank image file (BlockImage.gif) is displayed instead of a standard or security block page. This happens when the Advertisements category is blocked, and a site tries to display an image (like a GIF or JPG file) hosted at a URL in the Advertisements category.

In some cases, an entire site may be made up of advertisement images. In this case, the user will see a blank web page in the browser instead of a standard block message.

Users can tell that the site has been blocked because of the URL, which is something like this:

http://<Filtering Service IP address>:15871/cgi-bin/ blockpage.cgi?ws-session=<session number>