We started a campaign on Google AdWord's content network. Using Value Track, they let you use {placement} in your ad URL so that the name of the site where your ad appears is passed as a URL parameter to your site.

When we use this, we normally see the site name (like example.com) passed as a URL parameter. Some portion of the time, though, Google sends something like 123456.anonymous.google as the placement. It appears that Google allows sites to be anonymous from those advertising on them some of the time.

  • Under what circumstances does google anonymize the placement like this?
  • Why does Google anonymize some placements?
  • Does google use a different anonymous identifier for each site that sends traffic?

I've found that I can block ads that would show up anonymous.google if you want to.


Google anonymizes the placement when the publisher has chosen to be anonymous. This surprises me somewhat because I am an AdSense publisher and I don't know of any setting in AdSense for anonymity from advertisers. Perhaps only third party ad networks give publishers this option. (source)

Google does use a different id for each and every publisher. I see the following in my placement report, each representing a different anonymous website:

  • bcbc91e082d63f76.anonymous.google
  • 055a6a4b8cb148b7.anonymous.google
  • 1755de1211e7e9e4.anonymous.google

This allows an advertiser to block individual anonymous websites based on performance, or all anonymous websites.

The alpha-numeric identifier (the 123456 portion) is Google's publisher ID. This isn't strictly anonymous. This publisher ID is used on the website that shows there ad. For example, it is used in the JavaScript snippet for Google Adsense. That can be unmasked by finding the website that has that tracking code. Here is a promotional video from a company that built a product that they claims does so.

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