'Convert existent zone to slave.
:param zone: Zone to convert.
:type  zone: :class:`Zone`
:param master: the specified master name server IP address.
:type  master: ``str``
:rtype: Bool'

def ex_convert_to_secondary(self, zone, master):

    action = '/app/dns/converttosecondary.jsp?'
    params = {'name': zone.domain, 'master': master}
    try:
        self.connection.request(action=action, params=params)
    except ZonomiException:
        e = sys.exc_info()[1]
        if ('ERROR:    Could    not    find' in e.message):
            raise ZoneDoesNotExistError(zone_id=zone.id, driver=self, value=e.message)
    return True
