Which port is commonly used by MQTT over TLS for secure connections?

Which port is commonly used by MQTT over TLS for secure connections?

• A. 443 TCP
• B. 1883 TCP
• C. 21 TCP
• D. 8883 TCP

Answer: (D)

MQTT over TLS is commonly called MQTTS, and the standard port for secure MQTT sessions is 8883. This port is recognized as the default for encrypted MQTT connections, so clients connect with TLS enabled to 8883 to ensure encryption and authentication. The other ports serve different purposes: 1883 is the default for plain MQTT without TLS, 21 is FTP, and 443 is typically used for HTTPS (TLS-enabled web traffic), not the standard MQTT secure port. Therefore, 8883 is the correct choice for MQTT over TLS.

MQTT over TLS is commonly called MQTTS, and the standard port for secure MQTT sessions is 8883. This port is recognized as the default for encrypted MQTT connections, so clients connect with TLS enabled to 8883 to ensure encryption and authentication. The other ports serve different purposes: 1883 is the default for plain MQTT without TLS, 21 is FTP, and 443 is typically used for HTTPS (TLS-enabled web traffic), not the standard MQTT secure port. Therefore, 8883 is the correct choice for MQTT over TLS.