@staticmethod
def extract_zone(domain_name):
    """
        extract domain to root, sub, acme_txt
        :param str domain_name: the value sewer client passed in, like *.menduo.example.com
        :return tuple: root, zone, acme_txt
        """
    domain_name = domain_name.lstrip('*.')
    if domain_name.count('.') > 1:
        zone, middle, last = str(domain_name).rsplit('.', 2)
        root = '.'.join([middle, last])
        acme_txt = '_acme-challenge.%s' % zone
    else:
        zone = ''
        root = domain_name
        acme_txt = '_acme-challenge'
    return root, zone, acme_txt
