Topic configuration in Kafka - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of the topic configuration command?

You run the following Kafka command to create a topic with 3 partitions and a replication factor of 2. What will be the output message?

Kafka

kafka-topics.sh --create --topic my-topic --partitions 3 --replication-factor 2 --bootstrap-server localhost:9092

A Created topic my-topic.

B Error: Replication factor larger than available brokers.

C Topic my-topic already exists.

D Warning: Partitions must be at least 1.

💡 Hint

Check if the cluster has at least 2 brokers to support replication factor 2.

If the cluster has enough brokers, the topic is created successfully with the specified partitions and replication factor.

🧠 Conceptual

intermediate

What does the 'cleanup.policy' configuration control?

In Kafka topic configuration, what is the purpose of the 'cleanup.policy' setting?

A It specifies the replication factor for the topic.

B It sets the maximum message size allowed in the topic.

C It controls how Kafka deletes or compacts old log segments.

D It defines the number of partitions for the topic.

💡 Hint

Think about how Kafka manages old data in topics.

The 'cleanup.policy' can be 'delete' to remove old data or 'compact' to keep the latest record per key.

❓ Predict Output

advanced

What is the effect of setting 'min.insync.replicas' to 2?

Given a topic with replication factor 3, what happens if 'min.insync.replicas' is set to 2 and only 1 replica is in sync during a produce request?

A The produce request fails with a NotEnoughReplicasException.

B The produce request succeeds but with a warning logged.

C The produce request succeeds normally without any issues.

D The topic automatically increases the replication factor to 4.

💡 Hint

Consider what 'min.insync.replicas' means for message durability.

If the number of in-sync replicas is less than 'min.insync.replicas', Kafka rejects produce requests to ensure durability.

❓ Predict Output

advanced

What is the output of describing a topic with a retention.ms of 604800000?

You run the command to describe a topic and see the retention.ms configuration set to 604800000. What does this value represent?

Kafka

kafka-configs.sh --describe --entity-type topics --entity-name my-topic --bootstrap-server localhost:9092

A The topic retains messages for 1 day before deletion.

B The topic retains messages for 7 days before deletion.

C The topic retains messages indefinitely.

D The topic retention is disabled.

💡 Hint

Convert milliseconds to days to understand retention time.

604800000 milliseconds equals 7 days, so messages are kept for 7 days before being deleted.

🧠 Conceptual

expert

Which configuration ensures message order within a partition?

Which Kafka topic configuration guarantees that messages are consumed in the order they were produced within a partition?

A Setting 'cleanup.policy' to 'compact'.

B Setting 'retention.ms' to a high value.

C Setting 'min.insync.replicas' to the replication factor.

D Setting 'max.in.flight.requests.per.connection' to 1.

💡 Hint

Think about how Kafka handles message sending and retries.

'max.in.flight.requests.per.connection' set to 1 ensures messages are sent one at a time, preserving order.