Here's a tool that converts IP addresses into DNS hostnames. Great
for pentests and basket parties.
batchyDNS.pl (IP file)
The IP address file should be formatted with one IP address per line.
perl batchyDNS.pl iplist.txt
batchyDNS - A DNS recon tool
Created by Kevin Stadmeyer <firstname.lastname@example.org>
Copyright (C) 2009-2010 Trustwave Holdings, Inc.
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>