Concept Notes – IoT Communication Protocols
⚙️ What is IoT Communication?
In IoT (Internet of Things), multiple smart devices (sensors, actuators, appliances, etc.) need to exchange data with each other or with cloud servers. Communication protocols define how data is transmitted between devices, ensuring efficiency, security, and reliability.
1️⃣ MQTT (Message Queuing Telemetry Transport)
- Definition: A lightweight, publish–subscribe messaging protocol used in IoT.
- Designed for: Low bandwidth, high-latency, unreliable networks.
- How it Works:
- Devices (clients) send messages to a broker.
- The broker forwards messages to other subscribed clients.
- Example: Smart home sensors sending temperature data to a cloud dashboard.
- Advantages:
- Lightweight → suitable for small devices.
- Reliable delivery (QoS levels).
- Low power consumption.
- Use Cases: Smart homes, wearables, vehicle tracking.
2️⃣ HTTP (Hypertext Transfer Protocol)
- Definition: The protocol used by the web for communication between client and server.
- How it Works:
- IoT device (client) sends a request → server responds.
- Based on request-response model.
- Example: A smart fridge sending food inventory data to a mobile app via HTTP API.
- Advantages:
- Simple, widely supported.
- Easy integration with web services.
- Limitations:
- Heavy for small devices.
- Requires more bandwidth and power.
- Use Cases: Web dashboards, IoT devices connected to cloud APIs.
💡 Comparison Table – MQTT vs HTTP
| Feature | MQTT | HTTP |
|---|---|---|
| Model | Publish-Subscribe | Request-Response |
| Lightweight | Yes | No (heavier) |
| Bandwidth | Very low | High |
| Best Use | Small devices, sensor data | Cloud APIs, Web integration |
| Example | Temperature sensor → broker → mobile app | Smart fridge → cloud API → mobile app |
🔟 10 Most Expected MCQs – ECET 2026 (IoT Protocols)
Q1. MQTT protocol works on which communication model?
A) Request–Response
B) Publish–Subscribe
C) Peer-to-Peer
D) Client–Server
Q2. HTTP is mainly based on:
A) Publish–Subscribe
B) Request–Response
C) Broadcasting
D) Multicasting
Q3. Which is more suitable for low-power IoT devices?
A) HTTP
B) MQTT
C) FTP
D) SMTP
Q4. The central server in MQTT is called:
A) Client
B) Host
C) Broker
D) Gateway
Q5. Which protocol consumes more bandwidth?
A) MQTT
B) HTTP
C) Both equal
D) None
Q6. Which protocol ensures reliable message delivery using QoS?
A) MQTT
B) HTTP
C) CoAP
D) FTP
Q7. In HTTP, communication happens between:
A) Publisher and Subscriber
B) Client and Server
C) Broker and Client
D) Device to Device
Q8. Which protocol is widely used for web-based APIs in IoT?
A) MQTT
B) HTTP
C) SMTP
D) POP3
Q9. MQTT is best suited for:
A) Real-time sensor data
B) Web applications
C) File transfer
D) Email communication
Q10. Which IoT protocol is lightweight and suitable for battery-powered devices?
A) HTTP
B) MQTT
C) FTP
D) DNS
✅ Answer Key
| Q.No | Answer |
|---|---|
| Q1 | B |
| Q2 | B |
| Q3 | B |
| Q4 | C |
| Q5 | B |
| Q6 | A |
| Q7 | B |
| Q8 | B |
| Q9 | A |
| Q10 | B |
🧠 Explanations of Answers
- Q1 → B: MQTT works on publish–subscribe model.
- Q2 → B: HTTP uses request–response.
- Q3 → B: MQTT is lightweight, best for IoT sensors.
- Q4 → C: MQTT uses a broker for message distribution.
- Q5 → B: HTTP consumes more bandwidth compared to MQTT.
- Q6 → A: MQTT supports Quality of Service levels for reliable delivery.
- Q7 → B: HTTP follows client-server model.
- Q8 → B: HTTP is the backbone for REST APIs in IoT.
- Q9 → A: MQTT is used for real-time data in IoT.
- Q10 → B: MQTT is lightweight and battery-friendly.
🎯 Why Practice Matters for ECET 2026
IoT is a trending area in CSE syllabus, and protocol-based MCQs are common.
- By mastering MQTT & HTTP, you can answer 2–3 questions easily.
- Real-world knowledge helps in placements & interviews too, since IoT jobs are growing.
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