For those using it in Python, Gevent provides a pluggable set of DNS resolvers that monkey-patch the standard library's functions for async/cooperative use, including one built on c-ares: https://www.gevent.org/dns.html
Still alive and kicking in production for us! For situations where many requests are bound by external HTTP requests to third-party suppliers, it's an amazing way to allow for practically unlimited concurrency with limited cores.
