If you check your logs regularly, you might notice 404 errors which are valid. However, several times most of the 404 errors might not be a fault of yours at all.
One of the most annoying 404 errors I have had to deal was with Google’s Doubleclick DARTIframe 404 error, which was supposed to be used for expandable ads or Interstitial ads which needed to be displayed on the site.
More likely than not every website which uses Google AdSense or a Google display ad network might see an error as shown above. Clicking on the link will give you no clue as to what is wrong.
Thankfully, I found a thread, or rather a discussion which had an answer to solve this problem. You can read more about it here. However, if you are looking for a quick solution to fix the Ad.DoubleClick.Net DARTIframe 404 Error, here is the cause of the problem and how you can solve it.
Why Does This DARTIframe.html 404 Error Happen?
According to the document I read, and from what I know as a developer; in many cases expandable ads require permissions from the website it runs on while they do it in iFrames. This disallows them from displaying.
In most of these cases, ad networks use a workaround by hosting a file on the server they are running on to circumvent the issue. DoubleClick does it too. However, neither Google or DoubleClick have a FAQ or help topic listed about it.
How To Fix This Issue?
To fix the DoubleClick DARTIframe issue, you will need to create a new folder in the root directory of your website named as doubleclick. For example, the one we have here is http://techie-buzz.com/doubleclick/ and then upload a file provided by them called DARTIframe.html to that directory.
It is pretty simple, but not documented by Google itself which is shameful. Once you create the directory and upload the file you will not get 404 errors and your ad earnings might just go up.
You can download the ZIP file which contains the DARTIframe.html file and instructions to implement it from here. I hope this helps you to solve your problem.