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Apache Kafka Interview Questions

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by Ravindra Savaram
Last modified: July 16th 2021

If you're looking for Apache Kafka Interview Questions for Experienced or Freshers, you are at the right place. There are a lot of opportunities from many reputed companies in the world. According to research Apache Kafka has a market share of about 9.1%. So, You still have the opportunity to move ahead in your career in Apache Kafka Engineering. Mindmajix offers Advanced Apache Kafka Interview Questions 2021 that helps you in cracking your interview & acquire your dream career as Apache Kafka Engineer.

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Top 30 Apache Kafka Interview Questions

1. Explain what is Kafka?

Kafka is a publish-subscribe messaging application that is coded in “Scala”. It is an open-source message broker project which was started by the Apache software. The design pattern of Kafka is mainly based on the design of the transactional log.

Related Article: Kafka Tutorial

2. What are the different components that are available in Kafka?

The different components that are available in Kafka are as follows:

  1. Topic: this is nothing but a stream of messages that belong to the same type
  2. Producer: this is used for publishing messages to a specific topic
  3. Brokers: It is a set of servers that has the capability of storing publisher messages.

Consumer- responsible for subscribing to various topics and pulls the data from different brokers

3. What is the role of offset in Kafka?

Offset is nothing but a unique id that is assigned to the partitions. The messages are contained in these partitions. The important aspect or use of offset is that it identifies every message with the id which is available within the partition.

4. What is a consumer group?

A consumer group is nothing but an exclusive concept of Kafka.

Within each and every Kafka consumer group, we will have one or more consumers who actually consume subscribed topics.

5. Explain the role of the zookeeper in Kafka?

Within the Kafka environment, the zookeeper is used to store offset-related information which is used to consume a specific topic and by a specific consumer group.

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6. Would it be possible to use Kafka without the zookeeper?

No, it is not possible to use Kafka without the zookeeper. The user will not able to connect directly to the Kafka server in the absence of a zookeeper. For some reason, if the zookeeper is down then the individual will not able to access any of the client requests.

7. Elaborate on the terms leader and follower in Kafka environment?

The concept of leader and follower is maintained in Kafka environment so that the overall system ensures load balancing on the servers.

  • For every partition in the Kafka environment, one server plays the role of leader, and the rest of the servers act as followers.
  • All the data read and write commands are executed at the leader level and the rest of the followers just have to replicate the process.
  • At the time of any server faults and the leader is not able to function appropriately then one of the followers will take the place of the leaders. Thus making the system stable and also helps in the load balancing of the server.

8. What does ISR stand in Kafka's environment?

ISR stands for In sync replicas.

They are classified as a set of message replicas that are synched to be leaders.

9. What is the replica? What does it do?

A replica can be defined as a list of essential nodes that are responsible to log for a particular partition, and it doesn't matter whether they actually play the role of a leader or not.

10. Why are the replications are considered critical in Kafka's environment?

The main reason why replications are needed because they can be consumed again in an uncertain event of machine error or program malfunction or the system is down due to frequent software upgrades. So to make sure to overcome these, replication makes sure that the messages published are not lost.

11. If the replica stays out of the ISR for a very long time, then what does it tell us?

If the replica stays out of the ISR for a very long time, or the replica is not in sync with the ISR then it means that the follower server is not able to grasp data as fast as the leader is doing. So basically the follower is not able to come up with the leader activities.

12. What is the process of starting a Kafka server?

As the Kafka environment is run on a zookeeper, one has to make sure to run the zookeeper server first and then ignite the Kafka server.

13. Explain what is a partitioning key?

Within the available producer, the main function of the partitioning key is to validate and direct the destination partition of the message. Normally, a hashing-based partitioner is used to assess the partition Id if the key is provided.

14. Within the producer can you explain when will you experience QueueFullException occur?

Well, if the producer is sending more messages to the broker and if it cannot handle this in the flow of the messages then we will experience QueueFullException.

The producers don't have any limitation so it doesn't know when to stop the overflow of the messages. So to overcome this problem one should add multiple brokers so that the flow of the messages can be handled perfectly and we won't fall into this exception again.

15. Define the role of Kafka producer API?

Kafka procedure API aims to do the producer functionality through one API call to the client.

In specific, Kafka producer API actually combines the efforts of Kafka. producer.SyncProducer and the Kafka.producer.async.Async Producer

16. Explain the main difference between Kafka and Flume?

Both Kafka and Flume are used for real-time processing where Kafka seems to be more scalable and you can trust the message durability.

17. Explain the Kafka architecture?

Kafka is nothing but a cluster that holds multiple brokers as it is called a distributed system.
The topics within the system will hold multiple partitions.

Every broker within the system will hold multiple partitions. Based on this the producers and consumers actually exchange the message at the same time and the overall execution happens seamlessly.

18. What are the advantages of Kafka technology?

The following are the advantages of using Kafka technology:

  1. It is fast
  2. It comprises brokers. Every single broker is capable of handling megabytes of data.
  3. It is scalable
  4. A large dataset can be easily analyzed
  5. It is durable
  6. It has a distributed design that is robust in nature

19. Is apache Kafka is a distributed streaming platform? if yes, what you can do with it?

Yes, Apache Kafka is a streaming platform. A streaming platform contains the vital three capabilities, are as follows:

  1. It will help you to push records easily
  2. It will help you store a lot of records without giving any storage problems
  3. It will help you to process the records as they come in

20. What can you do with Kafka?

With the help of Kafka technology we can do the below:

  1. We can build a real-time stream of data pipelines which will help to transmit data between two systems
  2. Build a real-time streaming platform that can actually react to the data

21. What is the core API in Kafka?

They are four main core API’s:

  1. Producer API
  2. Consumer API
  3. Streams API
  4. Connector API

All the communications between the clients happen over through high-performance language via TCP protocol.

22. Explain the functionality of producer API in Kafka?

The producer API is responsible where it will allow the application to push a stream of records to one of the Kafka topics.

23. Explain the functionality of Consumer API in Kafka?

The Consumer API is responsible where it allows the application to receive one or more topics and at the same time process the stream of data that is produced.

24. Explain the functionality of Streams API in Kafka?

The Streams API is responsible where it allows the application to act as a processor and within the process, it will be effectively transforming the input streams to output streams.

25. Explain the functionality of the Connector API in Kafka?

The Connector API is responsible where it allows the application to stay connected and keeping a track of all the changes that happen within the system. For this to happen, we will be using reusable producers and consumers who stay connected to the Kafka topics.

26. Explain what is a topic?

A topic is nothing but a category classification or it can be a feed name out of which the records are actually published. Topics are always classified, the multi-subscriber.

27. What is the purpose of the retention period in the Kafka cluster?

Within the Kafka cluster, it retains all the published records. It doesn’t check whether they have been consumed or not. Using a configuration setting for the retention period, the records can be discarded. The main reason to discard the records from the Kafka cluster is that it can free up some space.

28. Highlights of Kafka system?

  1. It is dedicated to high performance
  2. Low latency system
  3. Scalable storage system
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29. What are the main components where the data is processed seamlessly in Kafka?

The main components where the data is processed seamlessly is:

  1. Producers
  2. Consumers

30. Is apache Kafka is an open-source stream processing platform?

Yes, Apache Kafka is an open-source stream processing platform.

About Author

NameRavindra Savaram
Author Bio


Ravindra Savaram is a Content Lead at Mindmajix.com. His passion lies in writing articles on the most popular IT platforms including Machine learning, DevOps, Data Science, Artificial Intelligence, RPA, Deep Learning, and so on. You can stay up to date on all these technologies by following him on LinkedIn and Twitter.