I recently implenented a ad serving tool made with PHP/MySQL. This obviously includes tracking of the ad impressions.
For tracking, I have one script for gif, jpg, and swf ads that increments a record for that specific ad and then passthru's the binary data. For HTML ads, I do the same thing basically, but I use a different script that tracks through a 1x1 gif that is displayed along with the ad's HTML.
Recently I have noticed days where the impressions tracked by my ad server tool exceeded what is shown for the same ads in the server logs. I could understand that situation being true if it was reversed, but I really don't know how its happening this way.
I don't think the problem is a bug in my code, but rather some exceptions I don't know about having to do with how server logs work, or maybe search engines spidering the pages that the ads appear on, or something like that.
Any ideas? or any good resources for this type of project?
Thanks in advance.
