Far too complex!

#! /usr/bin/perl -w

use strict;
use Socket;

for( @ARGV ) {
   if( my $host = gethostbyaddr( inet_aton($_), AF_INET )) {
        print "$_ is $host\n";
    }
    else {
        print "$_ NXDOMAIN\n";
    }
}
[download]

Works on my machine :)

Note that this will return one record. If you are doing funky things with multiple A or PTR records it might miss the information you're interested in. In which case the Net::DNS module will let you iterate through the RR set. Otherwise it's overkill.