If you’re preparing for a tech role involving real-time data streaming, messaging systems, or event-driven architectures, Apache Kafka is a technology you must master. In this guide, we bring you the top Kafka interview questions that help you understand everything from basics to advanced features, commonly asked in interviews for roles like Data Engineer, Kafka Developer, or System Architect.
Let’s dive into the most relevant Kafka interview questions to strengthen your preparation.
Top 25 Kafka Interview Questions and Answers
1. What is Kafka and why is it used?
Apache Kafka is an open-source distributed event streaming platform used for high-throughput, fault-tolerant, real-time data feeds. It is used for building real-time data pipelines and streaming apps.
2. What are the 4 major Kafka APIs?
The four core Kafka APIs are:
- Producer API: Sends data to topics.
- Consumer API: Reads data from topics.
- Streams API: Transforms data within Kafka.
- Admin API: Manages topics, brokers, and other configurations.
3. Explain the concept of a Kafka Topic.
A topic in Kafka is a category or feed name to which records are published. Topics are split into partitions, which help with parallel processing and scaling.
4. What is a Kafka Partition?
Partitions allow Kafka to scale horizontally by distributing data across multiple brokers. Each partition is an ordered, immutable sequence of records.
5. How does Kafka ensure message durability?
Kafka stores messages on disk and replicates them across brokers. Data can survive broker failures due to this replication.
6. What is Kafka Broker?
A Kafka Broker is a server that stores data and serves client requests. A Kafka cluster is made up of multiple brokers.
7. What is Zookeeper’s role in Kafka?
ZooKeeper manages the Kafka cluster’s metadata and broker coordination. In newer versions (KRaft mode), Kafka is moving away from ZooKeeper.
8. What are Kafka Consumers and how do they work?
Consumers subscribe to topics and read data in real-time. Kafka assigns partitions to consumers within a group for load balancing.
9. What is a Kafka Producer?
A Kafka Producer sends records (key-value pairs) to Kafka topics. It handles buffering, batching, and partitioning.
10. What is the retention period in Kafka?
Kafka can retain messages for a configured period (e.g., 7 days), or until a log size limit is reached, depending on the topic settings.
11. Explain Kafka’s “at least once” delivery guarantee.
Kafka ensures that messages are delivered at least once, but duplicates may occur unless exactly-once semantics are enabled.
12. What is Kafka Streams?
Kafka Streams is a Java library used to build real-time, scalable, fault-tolerant stream processing applications using Kafka.
13. How is Kafka different from RabbitMQ or ActiveMQ?
Kafka is designed for high-throughput distributed processing, while RabbitMQ is better for low-latency messaging with complex routing logic.
14. What are Kafka Connectors?
Kafka Connect is a tool to move data between Kafka and other systems like databases or HDFS using source and sink connectors.
15. What is a Consumer Group in Kafka?
A group of consumers that collaborate to read data from a topic’s partitions. Each partition is consumed by one member of the group.
16. How does Kafka achieve fault tolerance?
Through replication across brokers. If a broker fails, data is served by another in-sync replica.
17. What are offsets in Kafka?
An offset is a unique ID assigned to each message in a partition. Consumers track these to resume reading.
18. How can we monitor Kafka?
Using tools like Kafka Manager, Prometheus, Grafana, or Kafka’s JMX metrics.
19. What are the advantages of Kafka?
Scalability, durability, fault tolerance, high throughput, and real-time data processing.
20. What is idempotence in Kafka producers?
It ensures that even if a producer sends the same record multiple times, it is written only once to the topic.
21. How do Kafka partitions improve performance?
They allow parallel processing and horizontal scaling by distributing the load.
22. Can Kafka handle millions of messages per second?
Yes. Kafka is designed to handle high-throughput scenarios with minimal latency.
23. What are in-sync replicas (ISR)?
Replicas that have caught up with the leader partition and are eligible for promotion if the leader fails.
24. What is log compaction in Kafka?
A mechanism to retain only the latest record for each key, useful for change-log or snapshot scenarios.
25. What is Kafka best used for?
Kafka is best used for:
- Real-time data pipelines
- Log aggregation
- Stream processing
- Event sourcing
- Metrics collection
People Also Ask
What are the 4 major Kafka APIs?
Kafka offers four powerful APIs:
- Producer API – For sending messages.
- Consumer API – For reading messages.
- Streams API – For stream processing.
- Admin API – For managing Kafka infrastructure.
What is Kafka and why it is used?
Kafka is a highly scalable, distributed platform for streaming data. It’s used for building data pipelines, messaging systems, and event-driven microservices.
What are the basics of Kafka?
Kafka basics include:
- Topics and Partitions
- Producers and Consumers
- Brokers and Clusters
- Offsets and Retention
- Message Delivery Guarantees
What is Kafka best used for?
Kafka excels at:
- Real-time analytics
- Log ingestion and processing
- Event-driven architectures
- Scalable microservices communication
Final Thoughts
Mastering these Kafka interview questions is key to standing out in your next technical interview. Whether you’re a beginner trying to grasp Kafka basics or an experienced engineer aiming for system design interviews, these questions offer both depth and practical insights.
Ready to boost your confidence and technical edge? Bookmark this guide and keep practicing.