Replication factor in Kafka - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to set the replication factor to 3 when creating a Kafka topic.

Kafka

kafka-topics --create --topic my-topic --partitions 1 --replication-factor [1] --bootstrap-server localhost:9092

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

A1

B3

C0

D5

Attempts:

3 left

💡 Hint

Common Mistakes

Setting replication factor to 0 causes an error.

Using replication factor 1 means no replication.

The replication factor defines how many copies of the data are kept across Kafka brokers. Setting it to 3 means the data is replicated on 3 brokers.

2fill in blank

medium

Complete the code to describe the replication factor of the topic named 'orders'.

Kafka

kafka-topics --describe --topic orders --bootstrap-server localhost:9092 | grep ReplicationFactor:[1]

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

A3

B1

C2

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using 0 or 1 will not show the expected replication factor.

Confusing partition count with replication factor.

The command filters the topic description to show lines with replication factor 3, which is common for production topics.

3fill in blank

hard

Fix the error in the command to create a topic with replication factor 2.

Kafka

kafka-topics --create --topic test-topic --partitions 3 --replication-factor [1] --bootstrap-server localhost:9092

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

A2

B4

C0

D-1

Attempts:

3 left

💡 Hint

Common Mistakes

Using 0 or negative numbers causes errors.

Setting replication factor higher than broker count causes errors.

Replication factor must be a positive integer and cannot exceed the number of brokers. 2 is valid if you have at least 2 brokers.

4fill in blank

hard

Fill both blanks to create a topic with 4 partitions and replication factor 3.

Kafka

kafka-topics --create --topic logs --partitions [1] --replication-factor [2] --bootstrap-server localhost:9092

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

A4

B3

C2

D1

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up partitions and replication factor values.

Using replication factor higher than available brokers.

The topic 'logs' is created with 4 partitions and a replication factor of 3 for good parallelism and fault tolerance.

5fill in blank

hard

Fill all three blanks to create a topic with replication factor 2, 5 partitions, and bootstrap server at localhost:9093.

Kafka

kafka-topics --create --topic metrics --partitions [1] --replication-factor [2] --bootstrap-server [3]

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

A5

B2

Clocalhost:9093

Dlocalhost:9092

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong port for bootstrap server.

Confusing partitions with replication factor.

This command creates the 'metrics' topic with 5 partitions, replication factor 2, and connects to the Kafka server at localhost:9093.

Practice

1.

What does the replication factor in Kafka control?

easy

A. The size limit of each partition

B. The number of copies of each partition stored across brokers

C. The number of partitions in a topic

D. The number of consumers in a consumer group

Solution

1. Step 1: Understand replication factor meaning

   The replication factor defines how many copies of each partition Kafka keeps on different brokers.

2. Step 2: Differentiate from other Kafka settings

   Partitions count and consumer group size are unrelated to replication factor.

3. Final Answer:

   The number of copies of each partition stored across brokers -> Option B

4. Quick Check:

   Replication factor = number of copies [OK]

Hint: Replication factor = copies of data stored [OK]

Common Mistakes:

• Confusing replication factor with partition count
• Thinking replication factor controls consumer groups
• Assuming replication factor limits partition size

2.

Which of the following is the correct way to set the replication factor when creating a Kafka topic using the command line?

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

easy

A. --replication-factor 3

B. --replication-factor=3

C. --replication_factor 3

D. --replicationFactor 3

Solution

1. Step 1: Check Kafka CLI syntax for replication factor

   The correct flag is --replication-factor with a space before the value.

2. Step 2: Identify incorrect options

   Options with underscores or camelCase are invalid flags; equals sign is not used here.

3. Final Answer:

   --replication-factor 3 -> Option A

4. Quick Check:

   Use double dash and hyphen for replication factor [OK]

Hint: Use double dash and hyphen for flags in Kafka CLI [OK]

Common Mistakes:

• Using underscore instead of hyphen
• Using equals sign instead of space
• Using camelCase flag names

3.

Given a Kafka topic created with --partitions 2 and --replication-factor 3, how many total replicas will Kafka store across the cluster?

medium

A. 6

B. 3

C. 5

D. 2

Solution

1. Step 1: Calculate replicas per partition

   Each partition has 3 replicas because replication factor is 3.

2. Step 2: Multiply by number of partitions

   2 partitions x 3 replicas each = 6 total replicas.

3. Final Answer:

   6 -> Option A

4. Quick Check:

   Partitions x Replication factor = Total replicas [OK]

Hint: Multiply partitions by replication factor [OK]

Common Mistakes:

• Confusing replication factor with total partitions
• Adding instead of multiplying partitions and replicas
• Ignoring replication factor in calculation

4.

What is wrong with this Kafka topic creation command?

kafka-topics.sh --create --topic logs --partitions 3 --replication-factor 5 --bootstrap-server localhost:9092

Assuming the Kafka cluster has only 3 brokers.

medium

A. Partitions must be equal to replication factor

B. Topic name cannot be 'logs'

C. Bootstrap server address is incorrect

D. Replication factor cannot be greater than the number of brokers

Solution

1. Step 1: Understand replication factor limits

   Replication factor must be less than or equal to the number of brokers to ensure each replica is on a different broker.

2. Step 2: Check cluster size vs replication factor

   Replication factor 5 is greater than 3 brokers, which is invalid.

3. Final Answer:

   Replication factor cannot be greater than the number of brokers -> Option D

4. Quick Check:

   Replication factor ≤ brokers [OK]

Hint: Replication factor must not exceed broker count [OK]

Common Mistakes:

• Thinking partitions must equal replication factor
• Ignoring cluster size limits
• Assuming topic names have restrictions here

5.

You want to create a Kafka topic with 4 partitions and a replication factor of 3 for high availability. However, your cluster has only 2 brokers. What is the best solution?

hard

A. Create the topic with 1 partition and replication factor 3

B. Set replication factor to 4 to match partitions

C. Increase the number of brokers to at least 3

D. Create the topic with replication factor 2 instead

Solution

1. Step 1: Check replication factor vs brokers

   Replication factor 3 requires at least 3 brokers to store replicas on different machines.

2. Step 2: Evaluate options

   Reducing replication factor lowers availability; increasing brokers meets requirement.

3. Final Answer:

   Increase the number of brokers to at least 3 -> Option C

4. Quick Check:

   Replication factor ≤ brokers for high availability [OK]

Hint: Match replication factor to broker count for safety [OK]

Common Mistakes:

• Setting replication factor higher than brokers
• Reducing partitions instead of brokers
• Ignoring availability requirements