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During an idle moment recently, I wondered if any IP addresses I use might have potentially valid hostnames matching their address. Does that make sense?

Here's an example: the IP address might have the hostname i.ii.iii.iv, but unfortunately the top level domain name .iv doesn't exist.

So, I wrote a script that grabs the list of country-specific TLDs and checks IP addresses you specify to see if any might have hostnames in roman numerals:

#!/usr/bin/perl use strict; use warnings; use LWP::Simple qw(mirror); use Roman qw(roman); use Fatal qw(open close mirror); my %ip_to_roman = do { my @ip = <DATA>; chomp @ip; map { $_ => roman_ip($_) } @ip; }; { mirror('', 'cctld-whois.h +tm'); open(my $fh, 'cctld-whois.htm'); my $page = do { local $/ = undef; <$fh> }; close $fh; while ($page =~ m{>\.(\w\w)(?:&nbsp;|&#150;)*([^<]+)}gms) { my ($tld, $country) = ($1, $2); $country =~ s/\s+/ /ms; IP: foreach my $address (keys %ip_to_roman) { next IP unless $ip_to_roman{$address} =~ m/\.$tld\z/ms; print "$address is $ip_to_roman{$address} in $country\n"; } } } sub roman_ip { my $ip = shift; return join '.', map { roman $_ } split(/\./, $ip); } # Put your IP addresses here __DATA__

This script has limitations: it reports some domain names that you can't register. Many TLDs, such as .uk do not allow arbitrary registrations such as Instead, you have to register,, etc.

So, what did I find out about my own addresses? I now know I want to register a .ci domain name, but apparently I need to get someone in the Ivory Coast to register this for me and I suspect this may not work as they might only allow or

Anyway, it was still a fun experiment.

In reply to IP addresses that might have hostnames in roman numerals by tomhukins

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