Built into our website we have a dead link checker. This link checker confirms the validity of a link from our website to an external website before the user is redirected there. Once the link has been confirmed the user is redirected to the link they clicked on.

Site admins will find in their server logs:

• Request Type: HTTP/1.0 HEAD (The only type of HTTP request this software uses)
• Referrer: the web address the visitor came from
• User Agent: NFC Dead Link Checker, http://nofusscomputing.com/wiki/public/help/dead_link_check

The HTTP status code that was returned to the link checker is what we use to progress or give the user an error message. our link checker recognizes the following HTTP status codes.

• 200: Success, Redirect user
• 301: Moved Permanently, Redirect user
• 302: Moved Temporarily, Redirect user
• 304: Not Modified, Redirect user
• 401: Authorization Required, Redirect user

If a site returns any other HTTP status code, the user is presented with an error message and not redirected to the link they clicked on.