static public function getSecondDomain($domain=null)
	{
	    $domain = !empty($domain) ? $domain : (isset($_SERVER['HTTP_HOST']) ? $_SERVER['HTTP_HOST'] : null);
	    $n = preg_match('/([^.]*\.)?([^.]*\.)?\w+\.\w+$/', $domain, $matches);
	    return $domain && isset($matches[2]) ? $matches[2] : (isset($matches[1]) ? $matches[1] : '');
	}