[batiudrami]

Sure but custom DNS is not something everyone can or will do, and businesses certainly won't allow it.

[shakna]

Sure, but there are a few caveats to that:

+ Firefox doesn't use the system DNS by default anymore (Defaults to the DoH provider, usually Cloudflare)

+ Chrome doesn't use the system DNS by default anymore (Defaults to Google's)

+ Businesses often set the default DNS to use Google's, not their ISPs.