Consumer API basics in Kafka - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the main role of a Kafka Consumer?

A Kafka Consumer reads data from Kafka topics. It subscribes to topics and processes the messages sent by producers.

beginner

What does 'subscribe()' method do in Kafka Consumer API?

The subscribe() method tells the consumer which topics to listen to. It allows the consumer to receive messages from those topics.

beginner

Explain what 'poll()' method does in Kafka Consumer API.

The poll() method fetches records from the Kafka broker. It waits for new messages and returns them for processing.

intermediate

Why is committing offsets important in Kafka Consumer?

Committing offsets tells Kafka which messages have been processed. This helps avoid processing the same message twice after a restart.

intermediate

What is the difference between automatic and manual offset commit?

Automatic commit happens periodically without user control, while manual commit lets the user decide when to save the offset after processing messages.

What method does a Kafka Consumer use to start receiving messages from a topic?

A subscribe()

B connect()

C send()

D commit()

The subscribe() method is used to tell the consumer which topics to listen to.

Which method fetches messages from Kafka for the consumer to process?

A read()

B fetch()

C receive()

D poll()

poll() is the method that retrieves messages from Kafka.

Why do consumers commit offsets?

A To send messages to Kafka

B To mark messages as processed

C To subscribe to topics

D To create new topics

Committing offsets marks messages as processed to avoid reprocessing.

What happens if a consumer does not commit offsets?

A It may reprocess messages after restart

B It will lose messages permanently

C It cannot subscribe to topics

D It will send duplicate messages

Without committing offsets, the consumer may read the same messages again after restarting.

Which of these is a valid way to control offset commits?

A Producer acknowledgments

B Automatic topic creation

C Manual commit

D Broker replication

Manual commit lets the consumer decide when to save offsets.

Describe the basic steps a Kafka Consumer takes to read messages from a topic.

Think about how the consumer connects, gets data, and remembers progress.

Explain why offset management is important in Kafka Consumer API.

Consider what happens if the consumer restarts.