[tptacek]

This weird idea of the delineation of responsibilities between the OS and applications has never actually been how things worked. For a very long time, the OS resolver libraries couldn't even reliably do asynchronous resolution, and applications like your browser provided their own. I think the notion that the OS "owns" DNS comes from the fact that people used to get their DNS servers from DHCP, and the OS's libraries automatically knew what servers DHCP had been configured. It's not like some kind of law of system design.