Why are requests being made to /eyeblaster on my website?

Question

My Adsense-supported website's error.log file has lots entries like this which I'm fairly sure are advert related:

[Fri Apr 12 07:19:57 2013] [error] [client IP] File does not exist: /var/www/[mywebsite]/htdocs/eyeblaster, referer: http://apac-bidder.mathtag.com/notify/iframe? [snip lots of junk]

What is it and is it harmful? Should I create an empty eyeblaster.html file to shut it up?

I also have another two that are like it - are they related?:

[Fri Apr 12 07:08:52 2013] [error] [client IP] File does not exist: /var/www/[mywebsite]/htdocs/7196176924447058959

[Fri Apr 12 07:13:58 2013] [error] [client IP] File does not exist: /var/www/[mywebsite]/htdocs/_sans

Answer 1

Take a look at StackOverflow question above - Determine which advertisement made a request to /eyeblaster/addineyev2.html. I think all will be revealed :).

Answer 2

Eyeblaster is an online advertising company now called Sizmek (formerly Mediamind).

As John mentioned, this file is used as an iframe buster, just like DoubleClick's iframe buster, which should be placed by a publisher on [www.example.com]/doubleclick/DARTIframe.html