This is c-ares, an asynchronous resolver library.  It is intended for
applications which need to perform DNS queries without blocking, or
need to perform multiple DNS queries in parallel.  The primary
examples of such applications are servers which communicate with
multiple clients and programs with graphical user interfaces.

WWW:	http://c-ares.haxx.se/
Author:	Daniel Stenberg <daniel@haxx.se>, Greg Hudson <ghudson@mit.edu>