most people don't run their own resolvers, so at best you're fingerprinting DNS server of the ISP.
>http caches
can be easily cleared, or mitigated entirely by extensions or browser (eg. multi account containers).
That’s not how it’s tracked commonly. Similar to HTTP caches, you can fingerprint visitors by how quickly a domain request resolves for them. Sure, all of this can be mitigated. But you have to even know what to mitigate. And given the most fanatical privacy folks aren’t aware of basic timing fingerprints is a good indicator that no one is mitigating it nearly as well as they might think.