mongoose/docs/c-api/dns.h/mg_set_protocol_dns.md

title	decl_name	symbol_kind	signature
mg_set_protocol_dns()	mg_set_protocol_dns	func	void mg_set_protocol_dns(struct mg_connection *nc);

Attach built-in DNS event handler to the given listening connection.

DNS event handler parses incoming UDP packets, treating them as DNS requests. If incoming packet gets successfully parsed by the DNS event handler, a user event handler will receive MG_DNS_REQUEST event, with ev_data pointing to the parsed struct mg_dns_message.

See captive_dns_server example on how to handle DNS request and send DNS reply.