CNStats 4.2 User Manual
"Links to Pages 404"
The report displays pages, from which users pass over to non-existent pages of your site. Actually, these are pages containing links to non-existent pages.
This report works in the same way as is the "Referrers" report.
You should set up a counter code for "404" pages at "404" page for correct displaying of the report. The counter code can be obtained via Configuration - Counter Code.
The web-server generates an error "404" and passes it to the client. Beside the response code "404", which is transferred in the header of HTTP response, the web-server passes over a standard page, containing the error text. The browser displays this page.
Using Apache web-server, you can create your own "404" page with the help of ErrorDocument command.
Note: Microsoft Internet Explorer replaces "404" page, obtained from the server, to its own page in case the page length does not exceed 512 bytes. Therefore, for correct display of "404" page, its size should be greater than 512 bytes.