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://www.pix.net/staff/djm/sw/fastresolve/