When checking the log files either using Google Analytics, StatCounter or any other means, one interesting information is the referrer. They show from where do visitors come from. Especially interesting are referrals not coming from organic searches. Every once in a while I noticed a strange referrer as it was showing visitor coming from an ad company googleads.g.doubleclick.net and the landing page was to a non-existing page giving 404 error. This article will explain why this happens and how to fix it.