Which means Google could cause ads to follow you around, for example. Again, I don't know what all they actually do or don't do with their DNS logs, but the quoted "promise" doesn't promise anonymity, just separation of you as a known Google user from you as a semi-anonymous but specific DNS user.

I'm reminded of the early days of the Snowden revelations, when the NSA was saying "it's just metadata."

I would think they'd just dump the data from all of their services into your advertising profile. They won't store your name and such, but they have to have a way of linking this anonymous profile to your google account or something. I doubt that google simply deletes all advertising profile data if you just happen to clear your cookies.

Remember when they said they don't combine data from different properties?

208.67.222.222

Although they've been bought by Cisco recently.

You could also just run your own local caching resolver that hits the real root nameservers for lookup.