 <p>I always liked evdns</p> <p><a href="http://linux.die.net/man/3/evdns" rel="nofollow">http://linux.die.net/man/3/evdns</a></p> <p>There appears to be a python binding called pyevent</p> <p><a href="http://code.google.com/p/pyevent/source/browse/trunk/evdns.pxi?r=44" rel="nofollow">http://code.google.com/p/pyevent/source/browse/trunk/evdns.pxi?r=44</a></p>