#! /usr/bin/perl -w

use strict;
use Socket;

while( <> ) {     
    chomp;
    my $host;
    if( $host = gethostbyaddr( inet_aton($_), AF_INET )) {
        print "$_ resolves to $host\n";
    }
    else {
        print "$_ has no DNS information\n";
    }
}