Interview Questions - MQTT

We collected frequently asked interview questions about MQTT for you:

Contents

1 MQTT Interview Questions 01 to 05
2 MQTT Interview Questions 05 to 10
3 Key differences
4 MQTT Uses & Applications
5 MQTT Vs CoAP Vs HTTP/HTTPS
6 MQTT Brokers
7 Next
- 7.1 Explore more

MQTT Interview Questions 01 to 05

What is MQTT?

MQTT is a lightweight and open-source protocol designed for efficient communication in low-bandwidth, high-latency, or unreliable networks.It follows a publish/subscribe model and finds widespread use in the Internet of Things (IoT) for enabling real-time and scalable messaging between devices./p>

Who developed MQTT?

Whats mean by Mqtt?

Utilizing a lightweight messaging protocol, it provides resource-constrained network clients with a simple way to distribute telemetry information.

What is the abbreviation of MQTT?

Message Queuing Telementary transport.

Where is MQTT used?

MQTT is now days using in IOT. Embedded system device to device communication using MQTT,

MQTT Interview Questions 05 to 10

MQTT is message oriented?

Yes, MQTT is message-oriented. The broker perceives each message as a discrete chunk of data, opaque to its internal workings

What kind of security level in MQTT?

What is the Port Standard follows by MQTT?

IANA reserves port 1883 specifically for MQTT usage, and TCP/IP hosts the standard ports of MQTT.

How save MQTT subscribe data into my PC?

To save MQTT subscribe data to your PC, you typically need a client application running on your computer. This application subscribes to the desired MQTT topics and stores the received data.

Step	Description
1.	Choose a MQTT Client: Select a MQTT client compatible with your programming language or platform.
2.	Install the MQTT Client: Install the chosen MQTT client on your PC, following the provided documentation.
3.	Subscribe to Topics: Write a script or program using the MQTT client to subscribe to specific topics.
4.	Implement a mechanism within your script to store received MQTT messages on your PC, such as a local file or database.
5.	Execute your script or program to initiate MQTT subscription and data storage.

How much max data can send over the MQTT?

According to the MQTT specification, the maximum PUBLISH length is 256Mb.

Key differences

how does it differ from traditional messaging protocols?

Lightweight: Designers crafted MQTT to be lightweight, minimizing the overhead of both the protocol and the exchanged messages, rendering it suitable for resource-constrained devices.
Publish/Subscribe Model: Unlike traditional point-to-point protocols, MQTT utilizes a publish/subscribe model, enabling multiple clients to subscribe to topics and receive relevant messages.
Asynchronous Communication: MQTT allows asynchronous communication, enabling devices to send and receive messages independently without establishing a persistent connection.
Quality of Service (QoS): MQTT provides users with the flexibility to choose between guaranteed delivery and optimized performance by offering different levels of Quality of Service (QoS) for message delivery.
Connectionless: Clients can connect and disconnect at any time without affecting other devices or the broker, as MQTT operates in a connectionless manner.
Retained Messages: MQTT’s support for retained messages ensures that the broker retains the last message sent on a topic, delivering it to new subscribers upon connection.
Low Bandwidth Overhead: Its binary format and small header size contribute to MQTT’s lower bandwidth overhead compared to text-based protocols, rendering it efficient for networks with limited bandwidth.

MQTT Uses & Applications

Various purposes widely use it, primarily in scenarios requiring efficient and lightweight communication.Here are some common uses of MQTT:

Use Case	Description
Internet of Things (IoT)	MQTT is widely used in IoT applications for lightweight and efficient communication between devices.
Home Automation	MQTT facilitates communication between smart home devices, coordinating actions through its model.
Telemetry and Remote Monitoring	Industries use MQTT for real-time data exchange and monitoring, especially over unreliable networks.
Industrial Automation	MQTT is utilized in industrial settings for SCADA systems, enabling communication between PLCs and sensors.
Mobile Applications	Integrated into mobile apps for real-time updates and notifications, providing reliable message delivery.
Weather Monitoring	MQTT is employed in weather monitoring systems for transmitting data from various sensors to a central server.
Healthcare	In healthcare, MQTT is used for monitoring patient data and facilitating communication between medical devices.
Energy Management	MQTT is utilized in energy management systems for efficient communication between meters, sensors, and control systems.
Smart Agriculture	MQTT aids in precision agriculture by enabling real-time monitoring of environmental conditions and crop health.
Vehicle Telematics	Used in the automotive industry for real-time communication between vehicles, fleet management systems, and central servers.

The versatility and efficiency of MQTT make it suitable for a diverse range of applications, contributing to its widespread

MQTT Vs CoAP Vs HTTP/HTTPS

These are general comparisons, and the choice of protocol depends on the specific requirements of the application, such as the need for low latency, bandwidth constraints, or the nature of the devices involved.

Feature	MQTT	CoAP	HTTP/HTTPS
Communication Model	Publish/Subscribe and Request/Response	Request/Response	Request/Response
Message Format	Binary and Text	Binary and Text	Text
Header Size	Small and fixed	Small and fixed	Larger variable
Bandwidth Usage	Low	Low	Higher
Connection Type	Persistent	Stateless (UDP)	Stateless (HTTP, Persistent in HTTPS)
Quality of Service (QoS)	Yes (Levels 0, 1, 2)	No	No
Security	Yes (SSL/TLS support)	Yes (DTLS support)	Yes (SSL/TLS support)
Use Cases	IoT, Real-time communication, Low latency	IoT, Constrained devices	Web applications, General-purpose
Transport Layer Protocol	TCP, TLS	UDP, DTLS	TCP, TLS (HTTPS)
Implementation Complexity	Moderate	Moderate	Simple to Moderate
Scalability	Highly Scalable	Scalable	Scalable
Common Industries	IoT, Home Automation, Industrial Automation	IoT, Smart Grids	Web Applications, APIs

MQTT Brokers

MQTT Broker	Description
Mosquitto	An open-source MQTT broker that is lightweight and widely used.
HiveMQ	A scalable and enterprise-grade MQTT broker suitable for large-scale deployments.
Eclipse Mosquitto	An Eclipse Foundation project providing a robust MQTT broker with support for various platforms.
EMQ X	A highly scalable and distributed MQTT broker suitable for IoT and enterprise-level applications.
RabbitMQ	Though primarily a message broker, RabbitMQ supports MQTT as one of its messaging protocols.
VerneMQ	A distributed and highly available MQTT broker with clustering capabilities.
IBM IoT MessageSight	Designed for high-throughput, low-latency messaging in IoT environments.
CloudMQTT	A cloud-based MQTT broker service offering scalable and reliable MQTT messaging for IoT applications.

These MQTT brokers vary in features, scalability, and suitability for different use cases, so the choice depends on the specific requirements of your project.