[uncletammy]

Through what mechanism is it possible for them do bypass custom DNS servers? Does DNS over other protocols prevent this tampering?

[pritambaral]

DNS traffic is plaintext. MITM is all that's needed to be able to bypass custom DNS servers. An ISP, obviously, has to be in an MITM position to be able to provide internet service.

Here's an example: https://jeff.vtkellers.com/posts/technology/force-all-dns-qu...