Kafka interview questions

108 real Kafka questions from the Big Data bank, as asked in Indian campus drives and tech interviews. Every question has a verified answer and an AI-tutor explanation on placd — free to start.

1. What is Kafka partition?

Junior
  1. A.a copy of a partition stored on another broker; one is the leader and the others follow for fault tolerance
  2. B.a Kafka producer that assigns sequence numbers so retries do not create duplicate records on a partition
  3. C.the position of a record within a partition
  4. D.the unit of parallelism and ordering within a topic
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3. Which statement is correct?

Junior
  1. A.Kafka partition — the default Kafka producer partitioner for null-key records that fills one partition per batch before switching, improving batching and throughput over round-robin
  2. B.Kafka partition — the Kafka topic config setting how long messages are kept before deletion regardless of consumption, independent of any consumer offsets
  3. C.Kafka partition — a set of consumers where each partition is read by exactly one member
  4. D.Kafka partition — the unit of parallelism and ordering within a topic
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4. What is Kafka consumer group?

Junior
  1. A.the set of in-sync replicas that are sufficiently caught up to the leader and eligible to be elected leader
  2. B.a class implementing Kafka's Partitioner interface to control which partition a record lands in beyond the default key-hash or sticky behavior
  3. C.a Kafka producer that writes to multiple partitions atomically using a transactional ID so consumers see all or none
  4. D.a set of consumers where each partition is read by exactly one member
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6. Which statement is correct?

Junior
  1. A.Kafka consumer group — a Kafka producer that assigns sequence numbers so retries do not create duplicate records on a partition
  2. B.Kafka consumer group — a set of consumers where each partition is read by exactly one member
  3. C.Kafka consumer group — achieved via idempotent producer + transactions + read_committed
  4. D.Kafka consumer group — the framework of reusable source and sink connectors that streams data between Kafka and external systems without custom producer or consumer code
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7. What is consumer group rebalancing?

Mid
  1. A.reassigning partitions when a consumer joins or leaves the group
  2. B.retention that keeps only the latest value per key
  3. C.a Kafka producer that writes to multiple partitions atomically using a transactional ID so consumers see all or none
  4. D.the default Kafka producer partitioner for null-key records that fills one partition per batch before switching, improving batching and throughput over round-robin
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9. Which statement is correct?

Mid
  1. A.consumer group rebalancing — the gap between the latest offset on a partition and the offset a consumer group has committed
  2. B.consumer group rebalancing — a Kafka producer that assigns sequence numbers so retries do not create duplicate records on a partition
  3. C.consumer group rebalancing — reassigning partitions when a consumer joins or leaves the group
  4. D.consumer group rebalancing — retention that keeps only the latest value per key
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10. What is acks=all?

Mid
  1. A.grouping multiple records into one request, controlled by batch.size and linger.ms, to raise throughput at the cost of latency
  2. B.a service storing versioned Avro, Protobuf, or JSON schemas and enforcing compatibility so producers and consumers evolve message formats safely
  3. C.a Kafka server that stores topic partitions, serves producer writes, and answers consumer fetches
  4. D.the producer setting requiring all in-sync replicas to acknowledge a write
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12. Which statement is correct?

Mid
  1. A.acks=all — the producer setting requiring all in-sync replicas to acknowledge a write
  2. B.acks=all — the framework of reusable source and sink connectors that streams data between Kafka and external systems without custom producer or consumer code
  3. C.acks=all — the Schema Registry setting (BACKWARD, FORWARD, FULL) governing which schema changes are allowed for a subject before registration is rejected
  4. D.acks=all — a service storing versioned Avro, Protobuf, or JSON schemas and enforcing compatibility so producers and consumers evolve message formats safely
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13. What is Kafka exactly-once?

Mid
  1. A.achieved via idempotent producer + transactions + read_committed
  2. B.a Kafka feature that spreads partition replicas across racks or availability zones to survive zone failures
  3. C.the framework of reusable source and sink connectors that streams data between Kafka and external systems without custom producer or consumer code
  4. D.a Kafka retention policy that keeps only the latest record per key, useful for changelog and state topics
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15. Which statement is correct?

Mid
  1. A.Kafka exactly-once — the Kafka topic config capping the size of a partition log on disk, triggering deletion of the oldest segments once exceeded
  2. B.Kafka exactly-once — a Kafka producer that writes to multiple partitions atomically using a transactional ID so consumers see all or none
  3. C.Kafka exactly-once — achieved via idempotent producer + transactions + read_committed
  4. D.Kafka exactly-once — the Schema Registry setting (BACKWARD, FORWARD, FULL) governing which schema changes are allowed for a subject before registration is rejected
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16. What is log compaction?

Mid
  1. A.retention that keeps only the latest value per key
  2. B.a Kafka feature that spreads partition replicas across racks or availability zones to survive zone failures
  3. C.the Kafka Connect-based replication tool that copies topics, configs, and consumer offsets across clusters with offset translation for disaster recovery and migration
  4. D.the unit of parallelism and ordering within a topic
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18. Which statement is correct?

Mid
  1. A.log compaction — a class implementing Kafka's Partitioner interface to control which partition a record lands in beyond the default key-hash or sticky behavior
  2. B.log compaction — retention that keeps only the latest value per key
  3. C.log compaction — a Kafka feature that spreads partition replicas across racks or availability zones to survive zone failures
  4. D.log compaction — a Kafka broker limit (bytes per second) applied per client or user to throttle producers and protect the cluster from being overwhelmed
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19. What is Kafka offset?

Junior
  1. A.grouping multiple records into one request, controlled by batch.size and linger.ms, to raise throughput at the cost of latency
  2. B.a Kafka record with a key and a null value that signals deletion of that key in a compacted topic, removed after delete.retention.ms
  3. C.the position of a record within a partition
  4. D.the Schema Registry setting (BACKWARD, FORWARD, FULL) governing which schema changes are allowed for a subject before registration is rejected
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21. Which statement is correct?

Junior
  1. A.Kafka offset — the unit of parallelism and ordering within a topic
  2. B.Kafka offset — a Kafka retention policy that keeps only the latest record per key, useful for changelog and state topics
  3. C.Kafka offset — a lightweight per-record transformation applied inside Kafka Connect to mask, route, or reshape messages as they flow through a connector
  4. D.Kafka offset — the position of a record within a partition
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22. What is Topic?

Junior
  1. A.a Kafka guarantee combining idempotent producers and transactions so consume-process-produce pipelines neither lose nor duplicate records
  2. B.a named, append-only log of records in Kafka that is split into partitions for parallelism and scale
  3. C.the Schema Registry setting (BACKWARD, FORWARD, FULL) governing which schema changes are allowed for a subject before registration is rejected
  4. D.the Kafka topic config capping the size of a partition log on disk, triggering deletion of the oldest segments once exceeded
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24. Which statement is correct?

Junior
  1. A.Topic — a lightweight per-record transformation applied inside Kafka Connect to mask, route, or reshape messages as they flow through a connector
  2. B.Topic — a Kafka producer that assigns sequence numbers so retries do not create duplicate records on a partition
  3. C.Topic — a named, append-only log of records in Kafka that is split into partitions for parallelism and scale
  4. D.Topic — retention that keeps only the latest value per key
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25. What is Replica?

Junior
  1. A.the consumer isolation level that returns only records from committed transactions and skips aborted ones, required for exactly-once reads
  2. B.a copy of a partition stored on another broker; one is the leader and the others follow for fault tolerance
  3. C.the gap between the latest offset on a partition and the offset a consumer group has committed
  4. D.the position of a record within a partition
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26. Which term means: "a copy of a partition stored on another broker; one is the leader and the others follow for fault tolerance"?

Junior
  1. A.Schema Registry
  2. B.Single Message Transform
  3. C.Replica
  4. D.Transactional producer
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27. Which statement is correct?

Junior
  1. A.Replica — the framework of reusable source and sink connectors that streams data between Kafka and external systems without custom producer or consumer code
  2. B.Replica — the producer setting requiring all in-sync replicas to acknowledge a write
  3. C.Replica — the unit of parallelism and ordering within a topic
  4. D.Replica — a copy of a partition stored on another broker; one is the leader and the others follow for fault tolerance
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28. What is ISR?

Junior
  1. A.achieved via idempotent producer + transactions + read_committed
  2. B.the Kafka topic config setting how long messages are kept before deletion regardless of consumption, independent of any consumer offsets
  3. C.the set of in-sync replicas that are sufficiently caught up to the leader and eligible to be elected leader
  4. D.a copy of a partition stored on another broker; one is the leader and the others follow for fault tolerance
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30. Which statement is correct?

Junior
  1. A.ISR — a Kafka feature that spreads partition replicas across racks or availability zones to survive zone failures
  2. B.ISR — the Kafka topic config setting how long messages are kept before deletion regardless of consumption, independent of any consumer offsets
  3. C.ISR — the set of in-sync replicas that are sufficiently caught up to the leader and eligible to be elected leader
  4. D.ISR — the producer setting requiring all in-sync replicas to acknowledge a write
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