" Google uses cookies, like the PREF cookie, to help personalize ads on Google properties, like Google Search, particularly when you aren’t signed in to a Google account. We also use cookies for advertising we serve outside of Google. Our main advertising cookie is called ‘id’ and it is stored in browsers under the domain doubleclick.net. We use others with names such as _drt_, FLC, NID and exchange_uid." [1]

Wouldn't this mean that only doubleclick.net is used for advertisement tracking?

[1] http://www.google.com/intl/en-US/policies/technologies/types...