Based upon your requirements I would do something like this. You might also add a hash of all valid TLD combinations, but that might be what you want to get. 

#!/usr/bin/perl -w
   
use strict;
   
while( my $url = <DATA> )
   {  chomp($url);
      my @Url = split(/\./,$url);
      if ( length($Url[$#Url]) == 3 )
          {   print "$url:\t\tTLD is '".$Url[$#Url]."'\n";
          }
      else
          {   print "$url:\t\tTLD is '".$Url[$#Url-1].".".$Url[$#Url].
+"'\n";
          }
   }
   
   1;
   
   __DATA__
   www.drane.fresel.co.uk
   www.drane2.ws.uk
   www.drane3.Intern.com

[download]

result: 

www.drane.fresel.co.uk:         TLD is 'co.uk'
www.drane2.ws.uk:               TLD is 'ws.uk'
www.drane3.Intern.com:          TLD is 'com'

[download]

I use this in a Spam detection program. It gets allot more complicated than this!

Good Luck.

"Well done is better than well said." - Benjamin Franklin

In reply to Re: Heuristic for parsing Host name and domain by flexvault
in thread Heuristic for parsing Host name and domain by persistence911

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