We currently have c-ares and Apple iOS DNS resolver support as compile time options. We might also be interested in a site-specific DNS resolver library. I think it's reasonable to make this a standard extension point.

@junr03 since you were last digging into this, any thoughts on whether it would be feasible to accommodate the various DNS resolvers this way?

CC @yanavlasov @antoniovicente @asraa @adisuissa @KBaichoo @akonradi