Topic deletion and cleanup in Kafka - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the command to delete a Kafka topic named 'my-topic'.

Kafka

kafka-topics.sh --delete --topic [1] --bootstrap-server localhost:9092

Drag options to blanks, or click blank then click option'

Aremove-topic

Bmy-topic

Cdelete-topic

Dtopic-delete

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect topic names.

Confusing command options.

The correct topic name to delete is 'my-topic'.

2fill in blank

medium

Complete the command to list all topics after deletion to verify removal.

Kafka

kafka-topics.sh --list --bootstrap-server [1]

Drag options to blanks, or click blank then click option'

Alocalhost:2181

Blocalhost:9093

Clocalhost:9092

Dlocalhost:8080

Attempts:

3 left

💡 Hint

Common Mistakes

Using ZooKeeper port instead of Kafka broker port.

Using wrong port numbers.

The bootstrap server port for Kafka is usually 9092.

3fill in blank

hard

Fix the error in the command to enable topic deletion in Kafka server properties.

Kafka

delete.topic.enable=[1]

Drag options to blanks, or click blank then click option'

Atrue

Bfalse

Cenabled

Dyes

Attempts:

3 left

💡 Hint

Common Mistakes

Setting the property to false or other invalid values.

Not restarting the Kafka server after change.

Setting delete.topic.enable to true allows topic deletion.

4fill in blank

hard

Fill both blanks to create a cleanup policy that deletes old log segments automatically.

Kafka

log.cleanup.policy=[1]
log.retention.hours=[2]

Drag options to blanks, or click blank then click option'

Adelete

Bcompact

C168

D720

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'compact' instead of 'delete' for cleanup policy.

Setting retention hours too low or too high without reason.

Setting log.cleanup.policy to delete enables automatic deletion. log.retention.hours sets retention time in hours (168 = 7 days).

5fill in blank

hard

Fill all three blanks to create a command that deletes a topic and waits for cleanup to complete.

Kafka

kafka-topics.sh --delete --topic [1] --bootstrap-server [2] && kafka-run-class kafka.tools.GetOffsetShell --broker-list [3] --topic [1]

Drag options to blanks, or click blank then click option'

Amy-topic

Blocalhost:9092

Dlocalhost:2181

Attempts:

3 left

💡 Hint

Common Mistakes

Using ZooKeeper port 2181 instead of broker port 9092.

Mismatching topic names.

The topic name is 'my-topic'. The bootstrap server and broker list use 'localhost:9092' for Kafka broker communication.

Practice

1. What is the correct Kafka configuration to enable topic deletion?

easy

A. topic.delete.enabled=false

B. enable.topic.removal=false

C. delete.topic.enable=true

D. allow.topic.delete=no

Solution

1. Step 1: Understand Kafka topic deletion setting

   The Kafka broker must have a configuration that explicitly allows topic deletion.

2. Step 2: Identify the correct configuration key

   The correct key is delete.topic.enable and it must be set to true to allow deletion.

3. Final Answer:

   delete.topic.enable=true -> Option C

4. Quick Check:

   Topic deletion enabled = delete.topic.enable=true [OK]

Hint: Look for 'delete.topic.enable' set to true in config [OK]

Common Mistakes:

• Confusing the config key name
• Setting the value to false
• Assuming deletion works without config change

2. Which command correctly deletes a Kafka topic named my-topic?

easy

A. kafka-delete-topic.sh --topic my-topic

B. kafka-topics.sh --delete --topic my-topic

C. kafka-topics.sh --remove --topic my-topic

D. kafka-topics.sh --drop --topic my-topic

Solution

1. Step 1: Identify the correct Kafka topic deletion command

   The official Kafka command to delete a topic uses kafka-topics.sh with the --delete flag.

2. Step 2: Verify the command syntax

   The correct syntax is kafka-topics.sh --delete --topic my-topic.

3. Final Answer:

   kafka-topics.sh --delete --topic my-topic -> Option B

4. Quick Check:

   Delete topic command = kafka-topics.sh --delete --topic [OK]

Hint: Use --delete flag with kafka-topics.sh to remove topics [OK]

Common Mistakes:

• Using wrong flags like --remove or --drop
• Using a non-existent script
• Omitting the --topic option

3. After running kafka-topics.sh --delete --topic test-topic, which command confirms the topic is deleted?

medium

A. kafka-topics.sh --alter --topic test-topic

B. kafka-topics.sh --describe --topic test-topic

C. kafka-topics.sh --create --topic test-topic

D. kafka-topics.sh --list

Solution

1. Step 1: Understand how to check existing topics

   Listing topics shows all current topics in Kafka, so deleted topics won't appear.

2. Step 2: Choose the command that lists topics

   kafka-topics.sh --list lists all topics, confirming if test-topic is gone.

3. Final Answer:

   kafka-topics.sh --list -> Option D

4. Quick Check:

   List topics to confirm deletion = kafka-topics.sh --list [OK]

Hint: List topics to verify deletion, deleted ones won't show [OK]

Common Mistakes:

• Using describe which errors if topic missing
• Trying to create or alter instead of checking
• Assuming deletion is immediate without checking

4. You tried to delete a topic but it still appears in the list. What is the most likely cause?

medium

A. The broker configuration delete.topic.enable is set to false

B. You used the wrong topic name in the delete command

C. Kafka does not support topic deletion

D. The topic is currently being produced to

Solution

1. Step 1: Check broker configuration for topic deletion

   If delete.topic.enable is false, Kafka ignores delete commands and topics remain.

2. Step 2: Understand other options

   Wrong topic name causes error, Kafka supports deletion if enabled, and producing to topic doesn't block deletion.

3. Final Answer:

   The broker configuration delete.topic.enable is set to false -> Option A

4. Quick Check:

   Deletion blocked if delete.topic.enable=false [OK]

Hint: Check delete.topic.enable=true to allow deletion [OK]

Common Mistakes:

• Assuming Kafka never supports deletion
• Ignoring broker config settings
• Thinking active producers block deletion

5. You want to automate cleanup of unused topics older than 30 days. Which approach best uses Kafka's topic deletion and cleanup features?

hard

A. Enable delete.topic.enable=true and run a script that lists topics, checks their creation date, and deletes old ones

B. Set log.retention.ms to 30 days and rely on Kafka to delete topics automatically

C. Manually delete topics from Kafka config files after 30 days

D. Disable topic deletion and archive topics instead

Solution

1. Step 1: Understand Kafka's automatic cleanup capabilities

   Kafka deletes old log segments inside topics but does not delete entire topics automatically based on age.

2. Step 2: Choose an automation method for topic deletion

   Enabling delete.topic.enable=true and scripting topic listing with date checks allows controlled deletion of old topics.

3. Final Answer:

   Enable delete.topic.enable=true and run a script that lists topics, checks their creation date, and deletes old ones -> Option A

4. Quick Check:

   Automate deletion with config + script, not just retention settings [OK]

Hint: Use delete.topic.enable plus scripts for automated topic cleanup [OK]

Common Mistakes:

• Expecting Kafka to delete topics automatically by age
• Editing config files manually for topic deletion
• Disabling deletion and expecting cleanup