HTTP vs MQTT trade-offs in IOT Protocols - Practice Questions

Challenge - 5 Problems

🧠 Conceptual

intermediate

Primary difference in communication style between HTTP and MQTT

Which statement best describes the main communication style difference between HTTP and MQTT?

A HTTP uses a request-response model, while MQTT uses a publish-subscribe model.

B HTTP uses a publish-subscribe model, while MQTT uses a request-response model.

C Both HTTP and MQTT use a request-response model.

D Both HTTP and MQTT use a publish-subscribe model.

💡 Hint

Think about how clients interact with servers in each protocol.

HTTP works by clients sending requests and servers responding. MQTT uses topics where clients publish messages and others subscribe to those topics.

🧠 Conceptual

intermediate

Energy efficiency trade-off between HTTP and MQTT

Why is MQTT generally more energy efficient than HTTP for IoT devices?

A MQTT uses larger packets which reduce the number of transmissions.

B HTTP keeps connections open longer than MQTT, saving energy.

C MQTT keeps connections open and sends small packets, reducing overhead.

D HTTP uses smaller packets than MQTT, making it more energy efficient.

💡 Hint

Consider connection persistence and packet size.

MQTT maintains a persistent connection and sends minimal data, which saves battery life on devices. HTTP opens and closes connections frequently, causing more energy use.

✅ Best Practice

advanced

Choosing protocol for real-time sensor data streaming

For a system that requires real-time sensor data streaming with minimal latency and reliable delivery, which protocol is best suited?

A MQTT, because it supports persistent connections and QoS levels.

B MQTT, because it uses UDP for faster transmission.

C HTTP, because it uses TCP which guarantees delivery.

D HTTP, because it is stateless and simple.

💡 Hint

Think about latency and message delivery guarantees.

MQTT supports persistent connections and Quality of Service (QoS) levels, making it ideal for real-time and reliable data streaming. HTTP is stateless and less suited for continuous streams.

❓ Troubleshoot

advanced

Troubleshooting MQTT connection issues

An IoT device using MQTT cannot maintain a connection to the broker. Which is the most likely cause?

A The device is using MQTT over TLS on port 80.

B The device is using HTTP instead of MQTT.

C The device is publishing messages without subscribing.

D The device is behind a firewall blocking MQTT port 1883.

💡 Hint

Consider network restrictions and default ports.

MQTT typically uses port 1883. Firewalls blocking this port prevent connection. Using HTTP or publishing without subscribing does not cause connection failure. MQTT over TLS usually uses port 8883, not 80.

🔀 Workflow

expert

Optimizing IoT device communication for low bandwidth

You need to optimize communication for IoT devices with very low bandwidth and intermittent connectivity. Which workflow best achieves this using MQTT?

A 2,1,3,4

B 1,2,3,4

C 1,3,2,4

D 1,3,4,2

💡 Hint

Consider the order of subscribing before publishing and power saving.

Devices should first establish connection, then subscribe to receive commands before publishing data. Disconnecting last saves power. Publishing before subscribing may miss commands.