In the current implementation the querying is done one-shot, in mdns_query_send the transaction id is set and it is checked in mdns_query_recv if the matching response if for this transaction (one-shot multicast DNS queries).
The implementation should also permit for continuous multicast DNS querying in which mdns_query_recv does not check the transaction id and the application is responsible if more responses are required, more information here
In the current implementation the querying is done one-shot, in mdns_query_send the transaction id is set and it is checked in mdns_query_recv if the matching response if for this transaction (one-shot multicast DNS queries). The implementation should also permit for continuous multicast DNS querying in which mdns_query_recv does not check the transaction id and the application is responsible if more responses are required, more information here