public function lookup($domain)
    {
        $result = $this->queryServer($domain);

        while (preg_match_all('/.*Whois Server: (.*)/', $result, $matches)) {
            $server = array_pop($matches[1]);

            if ($server) {
                $result = $this->queryServer($domain, $server);
            }
        }

        return $result;
    }