1. What is the main purpose of MQTT protocol?
a) Real-time video streaming
b) Lightweight machine-to-machine (M2M) communication
c) File transfer
d) Voice over IP
Answer: b) Lightweight machine-to-machine (M2M) communication
Explanation: MQTT (Message Queuing Telemetry Transport) protocol is specifically designed for lightweight M2M communication, making it ideal for scenarios where bandwidth and resource constraints are present, such as IoT devices.
2. Which MQTT method is used for subscribing to specific topics?
a) PUBLISH
b) SUBSCRIBE
c) CONNECT
d) DISCONNECT
Answer: b) SUBSCRIBE
Explanation: The SUBSCRIBE method is used in MQTT to subscribe to specific topics on the broker. Once subscribed, the client receives messages published to those topics.
3. Which component in MQTT architecture is responsible for storing messages until they are delivered to subscribers?
a) Subscriber
b) Publisher
c) Broker
d) Client
Answer: c) Broker
Explanation: The MQTT broker is responsible for receiving all messages, filtering them, deciding who is interested in them (based on subscriptions), and sending the messages to those interested clients.
4. In MQTT communication, what is a topic?
a) The message payload
b) The client identifier
c) The communication channel
d) The message destination
Answer: d) The message destination
Explanation: In MQTT, a topic is a unique identifier that is used to route messages from publishers to subscribers. It serves as the destination for messages.
5. What is SMQTT?
a) Secure MQTT
b) Simple MQTT
c) Scalable MQTT
d) Static MQTT
Answer: a) Secure MQTT
Explanation: SMQTT stands for Secure MQTT, which is an extension of MQTT that provides additional security features such as authentication, encryption, and access control.
6. Which protocol is commonly used for constrained devices in IoT environments due to its low overhead?
a) MQTT
b) CoAP
c) XMPP
d) AMQP
Answer: b) CoAP
Explanation: Constrained Application Protocol (CoAP) is commonly used in IoT environments because it is designed for constrained devices with low bandwidth and processing power, offering a lightweight communication protocol.
7. What are the two main types of CoAP messages?
a) GET and POST
b) REQUEST and RESPONSE
c) PUBLISH and SUBSCRIBE
d) CONNECT and DISCONNECT
Answer: b) REQUEST and RESPONSE
Explanation: CoAP messages can be broadly categorized into REQUEST messages, which are sent by clients to servers to request actions, and RESPONSE messages, which are sent by servers to respond to client requests.
8. Which model does CoAP follow for communication between clients and servers?
a) Push-Pull model
b) Request-Response model
c) Broadcast model
d) Peer-to-Peer model
Answer: b) Request-Response model
Explanation: CoAP follows a Request-Response model, where clients send requests to servers, and servers respond to those requests accordingly. This model is well-suited for constrained environments where simplicity and efficiency are crucial.
9. What is XMPP primarily used for?
a) Real-time communication
b) File transfer
c) Data storage
d) Video streaming
Answer: a) Real-time communication
Explanation: Extensible Messaging and Presence Protocol (XMPP) is primarily used for real-time communication, including instant messaging, presence information, and contact list maintenance.
10. Which of the following is a feature of AMQP?
a) Designed for real-time communication
b) Lightweight protocol for IoT devices
c) Supports complex routing scenarios
d) Based on a centralized communication model
Answer: c) Supports complex routing scenarios
Explanation: Advanced Message Queuing Protocol (AMQP) supports complex routing scenarios, making it suitable for enterprise messaging where sophisticated message routing and delivery patterns are required.