Apache Kafka 4.0 Interview Mastery: 1000+ Most Asked Q&A

The release of Apache Kafka 4.0 brings one of the most significant evolutions in the platform’s history, introducing groundbreaking improvements such as KRaft (Kafka Raft) mode, tiered storage, and advanced features in Kafka Streams and Kafka Connect. With enterprises rapidly adopting Kafka for real-time data streaming, event-driven architectures, and distributed systems, professionals need to stay ahead with the latest updates and deeply understand both concepts and hands-on scenarios.

This course, “Apache Kafka 4.0 Interview Mastery: 1000+ Most Asked Q&A,” is designed to help you crack Kafka interviews with confidence while ensuring you master the latest features in Kafka’s ecosystem. It goes beyond theoretical concepts and provides 1000+ conceptual and scenario-based questions with detailed answers, structured topic-wise for easy practice and revision.

Whether you are preparing for interviews, upgrading from older versions, or aiming to strengthen your Kafka fundamentals and advanced concepts, this course is a one-stop preparation guide.

Course Syllabus Overview

We have designed the syllabus to cover every crucial aspect of Kafka 4.0, ensuring you gain both breadth and depth of knowledge:

1. Getting Started

Introduction, Use Cases, Quick Start, Ecosystem

Upgrading to Kafka 4.0

KRaft vs ZooKeeper differences

Docker setup and compatibility

2. APIs

Producer, Consumer, Streams, Connect, and Admin APIs

3. Configuration

Broker, Topic, Producer, Consumer, and Connect configs

Source/Sink connectors

Tiered Storage configs

Configuration providers (EnvVar, File, Directory, etc.)

4. Design

Motivation, Persistence, and Efficiency

Message Delivery Semantics & Transactions

Replication, Log Compaction, Quotas

5. Implementation

Network Layer, Messages & Message Format

Logs and Distribution internals

6. Operations

Adding/Removing/Modifying Topics

Balancing Leadership & Replicas Across Racks

Mirroring Data Between Clusters

Multi-Tenancy setup, Monitoring, and Cluster Expansion

Tiered Storage & KRaft Monitoring

7. Security

Encryption with SSL

Authentication using SASL

Authorization & ACLs

Incorporating security in running clusters

8. Kafka Connect

Overview & User Guide

Configuring Connectors, Transformations, REST API

Error Reporting, Exactly-Once Support, Plugin Discovery

Connector Development & Schema Management

9. Kafka Streams

Writing your own Streams Applications

Core Concepts & Architecture

Developer Manual & Upgrade Guide

Conclusion

By the end of this course, you will have practiced 1000+ carefully designed questions and answers, covering both fundamentals and advanced Kafka 4.0 features. You’ll gain confidence in real-world scenario-based problem solving, making you interview-ready and a skilled Kafka professional. This course will serve as both a preparation guide for interviews and a practical knowledge booster for on-the-job expertise.

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Examples

Q: Which Maven artifact must be included to use the Streams API?

kafka-core

kafka-server

kafka-clients

kafka-streams

Correct Answer: kafka-streams

Explanation:

To work with Kafka’s Streams API, developers must include the kafka-streams Maven artifact. This artifact contains classes and APIs required for stream processing like KStream, KTable, joins, aggregations, windowing, and state stores. While kafka-clients only supports producer and consumer functionality, kafka-core and kafka-server are bundled within the broker and not exposed as independent dependencies for client-side stream processing.

Knowledge Area: Kafka Connect

Q: An administrator enables SASL_SSL but forgets to reconfigure clients. What happens when PLAINTEXT is closed?

Producers switch to idempotent write mode

Clients auto-upgrade to SASL_SSL

Brokers fall back to PLAINTEXT internally

Clients fail authentication and cannot connect

Correct Answer: Clients fail authentication and cannot connect

Explanation:

When SASL_SSL is enabled on brokers, clients must also be reconfigured with the correct security protocol, authentication mechanism, and credentials. If the administrator disables PLAINTEXT without updating client configurations, the clients will continue attempting to connect using the unsecured protocol and will be rejected. Kafka does not automatically upgrade client connections to SASL_SSL, nor do brokers silently fall back. This results in failed authentication and connection errors until client configurations are corrected.

Knowledge Area: Kafka Security (SASL/SSL Configuration)

Q: If a company wants to transform input events from topic A into enriched data for topic B, which API should be chosen?

Streams API

Connect API

Admin API

Producer API

Correct Answer: Streams API

Explanation:

The Kafka Streams API is specifically designed for real-time stream processing and transformation between Kafka topics. It allows developers to consume from topic A, apply transformations, aggregations, or enrichments, and then produce results to topic B. Connect API is used for integrating Kafka with external systems, Admin API manages cluster operations, and Producer API only publishes raw events without transformation logic.

Knowledge Area: Kafka Streams