#!/usr/bin/perl -w

use strict;
use Socket;

while ( <DATA> ) {
    chomp;

    print +(
        gethostbyaddr( inet_aton($_), AF_INET )
    )[0], $/;
}

__DATA__
66.39.54.27
209.197.123.153
216.109.127.30
205.188.244.138