DNS::isDomain PHP Method

    function isDomain($domain)
    {
        if (preg_match("/^([a-zA-Z0-9]([a-zA-Z0-9\\-]{0,61}[a-zA-Z0-9])?\\.)+[a-zA-Z]{2,6}\$/", $domain)) {
            return true;
        } else {
            return false;
        }
    }