Topic configuration in Kafka - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a Kafka topic with 3 partitions.

Kafka

bin/kafka-topics.sh --create --topic my-topic --partitions [1] --bootstrap-server localhost:9092

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

A5

B1

C0

D3

Attempts:

3 left

💡 Hint

Common Mistakes

Using 0 partitions which is invalid.

Using a string instead of a number.

The --partitions option sets the number of partitions for the topic. Here, 3 partitions are specified.

2fill in blank

medium

Complete the code to set the replication factor to 2 when creating a Kafka topic.

Kafka

bin/kafka-topics.sh --create --topic my-topic --replication-factor [1] --bootstrap-server localhost:9092

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

A3

B2

C1

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Setting replication factor to 0 which is invalid.

Setting replication factor higher than available brokers.

The --replication-factor option sets how many copies of the data are kept. Here, 2 copies are specified.

3fill in blank

hard

Fix the error in the command to set the cleanup policy to 'compact' for a Kafka topic.

Kafka

bin/kafka-configs.sh --alter --entity-type topics --entity-name my-topic --add-config cleanup.policy=[1] --bootstrap-server localhost:9092

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

Adelete

Bcompact,delete

Ccompact

Dcompress

Attempts:

3 left

💡 Hint

Common Mistakes

Using an invalid cleanup policy value.

Using 'compress' which is not a valid cleanup policy.

The cleanup.policy can be set to compact to enable log compaction on the topic.

4fill in blank

hard

Fill both blanks to create a topic with 4 partitions and a retention time of 1 day (86400000 ms).

Kafka

bin/kafka-topics.sh --create --topic my-topic --partitions [1] --config retention.ms=[2] --bootstrap-server localhost:9092

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

A4

B86400000

C3600000

D2

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing retention time units.

Setting partitions to an invalid number.

The --partitions option sets 4 partitions. The retention.ms config sets retention time in milliseconds; 86400000 ms equals 1 day.

5fill in blank

hard

Fill all three blanks to create a topic named 'logs' with 6 partitions, replication factor 3, and cleanup policy 'delete'.

Kafka

bin/kafka-topics.sh --create --topic logs --partitions [1] --replication-factor [2] --config cleanup.policy=[3] --bootstrap-server localhost:9092

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

A3

B6

Cdelete

Dcompact

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up partitions and replication factor values.

Using invalid cleanup policy values.

The topic is created with 6 partitions, replication factor 3, and cleanup policy set to 'delete' to remove old data.

Practice

1. What does the retention.ms configuration control in a Kafka topic?

easy

A. How long messages are kept before deletion

B. The number of partitions in the topic

C. The replication factor of the topic

D. The maximum message size allowed

Solution

1. Step 1: Understand retention.ms meaning

   The retention.ms setting defines the time in milliseconds that Kafka retains messages before deleting them.

2. Step 2: Compare with other options

   Other options like partitions, replication factor, and message size are controlled by different configurations.

3. Final Answer:

   How long messages are kept before deletion -> Option A

4. Quick Check:

   retention.ms = message retention time [OK]

Hint: Retention means how long messages stay before removal [OK]

Common Mistakes:

• Confusing retention.ms with replication factor
• Thinking retention.ms controls partition count
• Assuming retention.ms limits message size

2. Which of the following is the correct syntax to create a Kafka topic with a replication factor of 3 using the command line?

easy

A. kafka-topics.sh --create --topic myTopic --replication-factor 3 --partitions 1 --bootstrap-server localhost:9092

B. kafka-topics.sh --create --topic myTopic --replication 3 --partitions 1 --bootstrap-server localhost:9092

C. kafka-topics.sh --create --topic myTopic --replica-factor 3 --partitions 1 --bootstrap-server localhost:9092

D. kafka-topics.sh --create --topic myTopic --replication-factor=3 --partitions 1 --bootstrap-server localhost:9092

Solution

1. Step 1: Identify correct option name

   The correct option for replication factor is --replication-factor without equals sign.

2. Step 2: Check syntax correctness

   kafka-topics.sh --create --topic myTopic --replication-factor 3 --partitions 1 --bootstrap-server localhost:9092 uses the correct syntax with spaces and proper option names; others have wrong option names or equals sign which is invalid here.

3. Final Answer:

   kafka-topics.sh --create --topic myTopic --replication-factor 3 --partitions 1 --bootstrap-server localhost:9092 -> Option A

4. Quick Check:

   Use --replication-factor with space, no equals [OK]

Hint: Use --replication-factor with space, no equals sign [OK]

Common Mistakes:

• Using --replication instead of --replication-factor
• Adding equals sign (=) after option name
• Misspelling replication-factor option

3. Given the command:
kafka-topics.sh --alter --topic logs --config retention.ms=60000 --bootstrap-server localhost:9092
What will be the effect on the topic logs?

medium

A. Messages will be retained indefinitely

B. The topic's replication factor will be set to 60000

C. The topic will be deleted after 60000 messages

D. Messages will be retained for 1 minute before deletion

Solution

1. Step 1: Understand the command's purpose

   The command alters the topic logs by setting retention.ms to 60000 milliseconds (1 minute).

2. Step 2: Interpret retention.ms effect

   This means messages older than 1 minute will be deleted automatically.

3. Final Answer:

   Messages will be retained for 1 minute before deletion -> Option D

4. Quick Check:

   retention.ms=60000 means 1 minute retention [OK]

Hint: retention.ms value is in milliseconds for message lifetime [OK]

Common Mistakes:

• Thinking retention.ms controls message count
• Confusing retention.ms with replication factor
• Assuming retention.ms disables deletion

4. You tried to set the cleanup policy of a Kafka topic with:
kafka-topics.sh --alter --topic data --config cleanup.policy=delete,compact --bootstrap-server localhost:9092
But it failed. What is the likely cause?

medium

A. The --alter command cannot change cleanup.policy

B. The cleanup.policy value is invalid; it must be either 'delete' or 'compact', not both

C. The topic name 'data' is reserved and cannot be altered

D. The bootstrap server address is incorrect

Solution

1. Step 1: Check cleanup.policy valid values

   Kafka allows cleanup.policy to be either 'delete' or 'compact' or both separated by comma, but the syntax must be exact and supported by the Kafka version.

2. Step 2: Identify common error

   Some Kafka versions or setups do not support combined policies or require no spaces; if the command failed, likely the value was invalid or syntax incorrect.

3. Final Answer:

   The cleanup.policy value is invalid; it must be either 'delete' or 'compact', not both -> Option B

4. Quick Check:

   cleanup.policy must be valid single or combined value [OK]

Hint: Check cleanup.policy values carefully; some setups disallow combined [OK]

Common Mistakes:

• Using unsupported combined cleanup policies
• Trying to alter topic with wrong bootstrap server
• Assuming topic names cannot be altered

5. You want to create a Kafka topic named events with 4 partitions, replication factor 2, and a retention time of 2 hours. Which command correctly sets all these configurations?

hard

A. kafka-topics.sh --create --topic events --partitions 4 --replication-factor 2 --config retention.ms=120 --bootstrap-server localhost:9092

B. kafka-topics.sh --create --topic events --partitions 2 --replication-factor 4 --config retention.ms=7200000 --bootstrap-server localhost:9092

C. kafka-topics.sh --create --topic events --partitions 4 --replication-factor 2 --config retention.ms=7200000 --bootstrap-server localhost:9092

D. kafka-topics.sh --create --topic events --partitions 4 --replication-factor 2 --config retention.ms=7200 --bootstrap-server localhost:9092

Solution

1. Step 1: Verify partitions and replication factor

   The topic requires 4 partitions and replication factor 2, so options with these exact values are correct.

2. Step 2: Calculate retention.ms for 2 hours

   2 hours = 2 * 60 * 60 * 1000 = 7,200,000 milliseconds. Only kafka-topics.sh --create --topic events --partitions 4 --replication-factor 2 --config retention.ms=7200000 --bootstrap-server localhost:9092 uses this correct retention.ms value.

3. Final Answer:

   kafka-topics.sh --create --topic events --partitions 4 --replication-factor 2 --config retention.ms=7200000 --bootstrap-server localhost:9092 -> Option C

4. Quick Check:

   Retention in ms for 2 hours = 7200000 [OK]

Hint: Convert hours to ms: hours * 3600000 for retention.ms [OK]

Common Mistakes:

• Mixing partitions and replication factor values
• Using retention.ms in seconds or minutes instead of ms
• Incorrect retention.ms calculation