get tdl with domain

function get_tdl($url) {
  // strip http:// and www.
  $tld = preg_replace("/^(https?:\/\/)?(www\.)?/i", "", $url);

  // strip everything else
  $tld = preg_replace("/\/.*$/", "", $tld);

  // extract and return tld
  $tld = substr($tld, strrpos($tld, ".") + 1);
  return $tld;
}