What is a characteristic of the message queueing telemetry transport (MQTT) publish-subscribe model?

What is a characteristic of the message queueing telemetry transport (MQTT) publish-subscribe model?

• It allows for a retained messages option that can be used to provide status updates.
• The last will and testament option allows for immediate session termination, thus saving power.
• Clients that are connected will prevent other clients from connecting, thus preserving power.
• Clients are prevented from subscribing to any subtopics in order to keep traffic to a minimum.

Explanation: MQTT is used for machine to machine (M2M) IoT communications and has an option to retain messages that can be used to provide status updates. MQTT allows clients to receive many messages when subscribed to a topic within subtopics. It also supports an option called the last will and testament option that ensures that the client receives the most current updates of the topics subscribed to. Clients connected do not prevent other clients from connecting and the traffic model that is used helps to keep traffic to a minimum, thus enabling reduction in power.

Exam with this question: IoT Security 1.1 Chapter 5 Quiz Answers