gistfile1.txt

  function ign_getDomain() {
	  $debug = true;
	  $res = $_SERVER['HTTP_HOST'];

	  if (false === ip2long($res)) { # This is a normal domain string
		$d = explode('.', $_SERVER['HTTP_HOST']);
		// $d_copy keeps code simple
		$d_copy = $d;
		// Make sure the last 2 values look like TLDs (no more than 3 characters). Not bulletproof (.info? .mobi?), but simple.
		if ( (count($d) > 2) && (strlen(array_pop($d_copy)) < 4) && (strlen(array_pop($d_copy)) < 4) ) {
			$res = join('.', array_slice($d, -3, 3));
		}
		else {
			$res = join('.', array_slice($d, -2, 2));
		}
		$res .= '.';	# ensure canonical end-of-string
	  }
	  else {
		  # This is an ip address. No action needed
	  }
	  if ($debug) dmp( $res );
	  return $res;
  }