Topic creation in Kafka - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this Kafka topic creation command?

Consider the following Kafka CLI command to create a topic named orders with 3 partitions and a replication factor of 2. What will be the output if the command runs successfully?

Kafka

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

A No output, command runs silently.

B Created topic orders.

C Warning: Replication factor larger than available brokers.

D Error: Topic orders already exists.

💡 Hint

Think about what the Kafka CLI prints when a topic is created successfully.

When a Kafka topic is created successfully using kafka-topics.sh, the CLI prints 'Created topic .' If the topic already exists, it prints an error. If replication factor is too high, it warns. It does not run silently.

🧠 Conceptual

intermediate

Which property defines the number of partitions when creating a Kafka topic?

When creating a Kafka topic, which configuration property controls how many partitions the topic will have?

A topic.partitions

B replication.factor

C partition.count

D num.partitions

💡 Hint

Look for the property name that clearly relates to partitions count.

The property 'num.partitions' defines how many partitions a Kafka topic will have. 'replication.factor' controls replication, others are invalid.

❓ Predict Output

advanced

What error does this Kafka topic creation command produce?

What error message will this command produce if there is only 1 broker running but the replication factor is set to 3?

Kafka

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

A Error: Replication factor: 3 larger than available brokers: 1

B Error: Topic logs already exists.

C Created topic logs.

D Warning: Partitions count less than replication factor.

💡 Hint

Replication factor cannot be larger than the number of brokers.

Kafka requires the replication factor to be less than or equal to the number of brokers. If not, it throws an error indicating replication factor is too large.

🚀 Application

advanced

How many partitions will the topic have after this command?

You run this command to create a topic without specifying partitions. The Kafka broker's default number of partitions is set to 4. How many partitions will the new topic have?

Kafka

kafka-topics.sh --create --topic payments --replication-factor 1 --bootstrap-server localhost:9092

A 4

B 1

C 0

D Depends on the client configuration

💡 Hint

If partitions are not specified, Kafka uses the broker default.

When partitions are not specified during topic creation, Kafka uses the broker's default number of partitions, which in this case is 4.

🔧 Debug

expert

Why does this topic creation command fail with a syntax error?

Identify the syntax error in this Kafka topic creation command and explain why it fails.

Kafka

kafka-topics.sh --create --topic "user-activity" --partitions 3 --replication-factor 1 --bootstrap-server localhost:9092

A Partitions must be specified after bootstrap-server.

B Replication factor must be greater than 1.

C Missing closing quote after topic name causes syntax error.

D Topic name cannot contain hyphens.

💡 Hint

Check the quotes around the topic name carefully.

The command is missing the closing double quote after the topic name, causing the shell to treat the rest as part of the string, leading to a syntax error.

Practice

1. What is the main purpose of a topic in Kafka?

easy

A. To compile Java programs

B. To store user login credentials

C. To manage database connections

D. To organize messages like folders organize files

Solution

1. Step 1: Understand Kafka topic role

   A Kafka topic is a category or feed name to which messages are published.

2. Step 2: Compare options with topic function

   Only To organize messages like folders organize files correctly describes topics as organizing messages like folders organize files.

3. Final Answer:

   To organize messages like folders organize files -> Option D

4. Quick Check:

   Topic = Organize messages [OK]

Hint: Topics group messages like folders group files [OK]

Common Mistakes:

• Confusing topics with databases
• Thinking topics store user data
• Mixing topics with program compilation

2. Which command correctly creates a Kafka topic named orders with 3 partitions and replication factor 2?

easy

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

B. kafka-create-topic orders 3 2

C. create-topic --name orders --partitions 3 --replicas 2

D. kafka-topics.sh --new --topic orders --partitions=3 --replicas=2

Solution

1. Step 1: Identify correct Kafka topic creation syntax

   The official command uses kafka-topics.sh with --create, --topic, --partitions, --replication-factor, and --bootstrap-server options.

2. Step 2: Match options with correct syntax

   kafka-topics.sh --create --topic orders --partitions 3 --replication-factor 2 --bootstrap-server localhost:9092 matches the correct syntax exactly; others use wrong commands or options.

3. Final Answer:

   kafka-topics.sh --create --topic orders --partitions 3 --replication-factor 2 --bootstrap-server localhost:9092 -> Option A

4. Quick Check:

   Correct syntax = kafka-topics.sh --create --topic orders --partitions 3 --replication-factor 2 --bootstrap-server localhost:9092 [OK]

Hint: Use kafka-topics.sh with --create and proper flags [OK]

Common Mistakes:

• Using wrong command names
• Missing --bootstrap-server option
• Incorrect option names like --replicas

3. What will happen if you run this command?

kafka-topics.sh --create --topic sales --partitions 5 --replication-factor 1 --bootstrap-server localhost:9092

medium

A. Creates a topic named 'sales' with 1 partition and replication factor 5

B. Fails because replication factor cannot be 1

C. Creates a topic named 'sales' with 5 partitions and replication factor 1

D. Fails due to missing zookeeper connection

Solution

1. Step 1: Analyze command parameters

   The command specifies topic 'sales', 5 partitions, replication factor 1, and bootstrap server.

2. Step 2: Understand Kafka topic creation rules

   Replication factor 1 is valid (means no replicas), and partitions set to 5 means 5 partitions created.

3. Final Answer:

   Creates a topic named 'sales' with 5 partitions and replication factor 1 -> Option C

4. Quick Check:

   Partitions=5, Replication=1 [OK]

Hint: Replication factor 1 means no replicas, partitions as given [OK]

Common Mistakes:

• Confusing partitions with replication factor
• Assuming replication factor 1 is invalid
• Expecting zookeeper connection with bootstrap-server

4. You tried to create a topic with this command:

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

What is the error?

medium

A. Missing --create flag

B. Invalid number for partitions: 'two' should be a number

C. Replication factor cannot be 3

D. Bootstrap server address is incorrect

Solution

1. Step 1: Check partitions parameter

   The partitions option expects a number, but 'two' is a word, causing a syntax error.

2. Step 2: Verify other parameters

   Replication factor 3 and bootstrap server are valid; --create flag is present.

3. Final Answer:

   Invalid number for partitions: 'two' should be a number -> Option B

4. Quick Check:

   Partitions must be numeric [OK]

Hint: Partitions must be numeric, not words [OK]

Common Mistakes:

• Using words instead of numbers for partitions
• Assuming replication factor 3 is invalid
• Forgetting --create flag

5. You want to create a Kafka topic for a critical system that must not lose messages and should handle high load. Which topic creation settings are best?

hard

A. Partitions: 10, Replication factor: 3

B. Partitions: 1, Replication factor: 1

C. Partitions: 5, Replication factor: 1

D. Partitions: 3, Replication factor: 2

Solution

1. Step 1: Understand requirements for critical system

   High load needs many partitions for parallelism; no message loss needs high replication factor.

2. Step 2: Evaluate options

   Partitions: 10, Replication factor: 3 has 10 partitions (high load) and replication factor 3 (high safety). Others have fewer partitions or lower replication.

3. Final Answer:

   Partitions: 10, Replication factor: 3 -> Option A

4. Quick Check:

   High load + safety = many partitions + high replication [OK]

Hint: More partitions + higher replication = speed + safety [OK]

Common Mistakes:

• Choosing low replication for safety
• Choosing few partitions for high load
• Ignoring replication factor importance