:param dns:
        :return:

def _create_dns_list(self, dns):
        """
        :param dns:
        :return:
        """
        if not dns:
            return None

        dns_list = []

        if isinstance(dns, six.string_types):
            if is_valid_ip(dns):
                dns_list.append(dns)
            else:
                raise ValueError("dns is required to be a valid ip adress. {0} was passed.".format(dns))
        elif isinstance(dns, list):
            for dns_entry in dns:
                if is_valid_ip(dns_entry):
                    dns_list.append(dns_entry)
            else:
                raise ValueError("dns is required to be a valid ip adress. {0} was passed.".format(dns))

        else:
            raise ValueError("dns and dns search must be a list or string. {0} was passed.".format(dns))

        return dns_list