Fastresolve is a package of programs to process web log files to get DNS
and domain ownership information for log analysis.  It sends out many
queries in parallel, and caches results, for speed.  Its DNS resolver is
about 10 times as fast as logresolve.pl from the Apache 1.3.9 distribution,
and about 50 times as fast as logresolve.c from that distribution.  It is
5-20 times as fast as the adnslogres program that comes with the adns
library, and about 3 times as fast as jdresolve, which is a Perl program
that uses similar algorithms.

WWW: http://BSDforge.com/projects/dns/fastresolve/