Explain Kafka partitions and delivery semantics
Company: Bloomberg
Role: Software Engineer
Category: System Design
Difficulty: hard
Interview Round: Technical Screen
Explain how Apache Kafka partitions, replication, and consumer groups work. How do these affect ordering, scalability, and fault tolerance? Compare at-most-once, at-least-once, and exactly-once delivery, and describe how you would implement idempotent, exactly-once processing end to end.
Overview: This question evaluates understanding of distributed messaging and stream-processing concepts—specifically Kafka internals such as partitions, replication, consumer groups, and delivery semantics—and the candidate's competency in reasoning about ordering, scalability, fault tolerance, and transactional guarantees.