dumresp LOCAL-ADDRESS LOCAL-PORT NUMBER-OF-PROCESSES [tcp]
dumresp accepts DNS packets on LOCAL-ADDRESS:LOCAL-PORT and simply replies with the same query, with the QR bit set. When NUMBER-OF-PROCESSES is set to anything but 1, dumresp will spawn NUMBER-OF-PROCESSES forks and use the SO_REUSEPORT option to bind to the port.
tcp: Whether to listen and accept TCP connections in addition to UDP packets. Defaults to false.
socket(7)