Internet-Security.com UDP port 5353 details

UDP port 5353 is used by Multicast DNS (mDNS) for local service discovery.
Apple’s Bonjour (mDNSResponder) on macOS and iOS uses 5353 to advertise and find AirPlay, AirPrint, and file-sharing services.
Avahi on Linux distributions (Ubuntu, Debian, Fedora, RHEL) and systemd-resolved handle mDNS on 5353 for DNS-SD service announcements.
Windows 10/11 implement mDNS on 5353 for device discovery; browsers like Google Chrome and Microsoft Edge use it to find Google Cast and WebRTC local devices.
Consumer devices using 5353 include Google Chromecast/Google Home, Sonos speakers, Philips Hue Bridge, Apple HomeKit accessories, and network printers from HP, Epson, and Canon.
Media and file-sharing apps such as iTunes/Apple Music, AirPlay speakers, and AirPrint printers rely on mDNS over 5353 to be discovered on the LAN.
Smart-home platforms like Home Assistant and Homebridge use 5353 to advertise integrations and discover devices.
Security note: Exposed 5353/UDP is often abused for reflection/amplification DDoS and can leak host/service info; mDNS responders (e.g., Apple mDNSResponder, Avahi) have had exploitable vulnerabilities historically.

UDP 5353