-Q, --query-port=<query_port>

Send outbound DNS queries from, and listen for their replies on, the specific UDP port <query_port> instead of using random ports. NOTE that using this option will make dnsmasq less secure against DNS spoofing attacks but it may be faster and use less resources. Setting this option to zero makes dnsmasq use a single port allocated to it by the OS: this was the default behaviour in versions prior to 2.43.