Don't forget Google's free hosting of Javascript libraries and webfonts. The cost of serving those is recouped by dropping a cookie on you. Also Google DNS can give them great insight into domain popularity.

>The cost of serving those is recouped by dropping a cookie on you.

Only if you allow third-party cookies. I'm honestly amazed that browsers haven't moved to turn third-party cookies off by default.

Yeah but there are no cookie in DNS queries. Tracking by IP is a lot more toothless than tracking by cookies / super-cookies.

IP based tracking still works most of the time. Dynamic IPs change very infrequently, and NAT combines IPs in physically (and often socially) close groups. It isn't perfect, but a lot of those requests can probably be mapped back to those cookies.

Google's entire business is based on building large database of tracking (and other) information; obviously their DNS is just another data source.

Just skip the recursive resolvers and run a local caching DNS server that starts from the root zones.

But you can't serve the same ads to the teenager of the family, Grandma and Dad...

And the IP may be a public network.

Akamai sold that business a few years ago:

https://www.akamai.com/us/en/about/news/press/2013-press/med...

That may be, but it seems that Akamai CDN is still giving them a data feed. From that press release:

"As a result of the pixel-free technology partnership, MediaMath's clients will gain access to more data for audience segmentation, retargeting, and optimization, with quick and easy activation."

Why a good VPN is pretty much a requirement now. I've been using F-Secure's products and really love seeing all the blocking it does.