Kafka installation and setup - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this Kafka console producer command?

You run the following command to send a message to a Kafka topic named test-topic. What will be the output shown in the terminal after sending the message?

Kafka

echo "Hello Kafka" | kafka-console-producer.sh --broker-list localhost:9092 --topic test-topic

A Error: Topic 'test-topic' does not exist

B Producer started, waiting for input

C Message sent successfully with no output

D Hello Kafka

💡 Hint

The console producer command sends the message silently unless there is an error.

The kafka-console-producer.sh command sends the message to the broker silently. It does not print the message or any confirmation unless there is an error.

🧠 Conceptual

intermediate

Which service must be running before starting Kafka broker?

Before starting the Kafka broker, which service must be running to ensure Kafka works properly?

A Zookeeper

B Kafka Connect

C Kafka Streams

D Kafka Producer

💡 Hint

Kafka uses this service to manage cluster metadata and leader election.

Kafka depends on Zookeeper to manage cluster metadata and coordinate brokers. Zookeeper must be running before Kafka starts.

🔧 Debug

advanced

Why does Kafka broker fail to start with this error?

You try to start Kafka broker but get this error: ERROR Fatal error during KafkaServer startup. The logs show Port 9092 already in use. What is the most likely cause?

Kafka

bin/kafka-server-start.sh config/server.properties

A Zookeeper is not running

B Another Kafka broker or process is already using port 9092

C The server.properties file is missing

D Kafka version is incompatible with Java version

💡 Hint

Check if any other process is using the default Kafka port.

The error indicates port 9092 is busy, so Kafka cannot bind to it. This usually means another Kafka broker or process is running on that port.

📝 Syntax

advanced

Which command correctly creates a Kafka topic named 'orders' with 3 partitions?

Select the correct command to create a Kafka topic named orders with 3 partitions and a replication factor of 1.

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

B kafka-topics.sh --create --topic orders --partition 3 --replication 1 --zookeeper localhost:2181

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

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

💡 Hint

Check the exact option names and syntax for partitions and replication factor.

Option A uses the correct option names and syntax for creating a topic with partitions and replication factor using --bootstrap-server.

🚀 Application

expert

How to configure Kafka broker to listen on all network interfaces?

You want your Kafka broker to accept connections from any IP address on your machine. Which configuration setting in server.properties achieves this?

A advertised.listeners=PLAINTEXT://0.0.0.0:9092

B advertised.listeners=PLAINTEXT://localhost:9092

C listeners=PLAINTEXT://127.0.0.1:9092

D listeners=PLAINTEXT://0.0.0.0:9092

💡 Hint

The listeners setting controls where Kafka binds to accept connections.

Setting listeners=PLAINTEXT://0.0.0.0:9092 makes Kafka listen on all network interfaces. advertised.listeners controls what Kafka tells clients to connect to.

Practice

1. What is the first step to start Kafka on your local machine?

easy

A. Start Zookeeper service

B. Create Kafka topics

C. Run Kafka producer

D. Install Java

Solution

1. Step 1: Understand Kafka dependencies

   Kafka requires Zookeeper to coordinate its services.

2. Step 2: Start Zookeeper before Kafka

   You must start Zookeeper first to allow Kafka to connect and run properly.

3. Final Answer:

   Start Zookeeper service -> Option A

4. Quick Check:

   Kafka needs Zookeeper first = Start Zookeeper service [OK]

Hint: Always start Zookeeper before Kafka server [OK]

Common Mistakes:

• Starting Kafka before Zookeeper
• Skipping Zookeeper start
• Trying to create topics before server runs

2. Which command correctly starts the Kafka server after Zookeeper is running?

easy

A. bin/kafka-topics.sh --create --topic test

B. bin/zookeeper-server-start.sh config/zookeeper.properties

C. bin/kafka-server-start.sh config/server.properties

D. bin/kafka-console-producer.sh --topic test

Solution

1. Step 1: Identify Kafka server start command

   The Kafka server is started using kafka-server-start.sh with server properties.

2. Step 2: Differentiate from other commands

   Zookeeper start uses zookeeper-server-start.sh; topic creation and producer commands are different tools.

3. Final Answer:

   bin/kafka-server-start.sh config/server.properties -> Option C

4. Quick Check:

   Kafka server start = bin/kafka-server-start.sh config/server.properties [OK]

Hint: Kafka server uses kafka-server-start.sh script [OK]

Common Mistakes:

• Using zookeeper start command for Kafka
• Confusing topic creation with server start
• Running producer before server

3. What will be the output when you run this command after starting Kafka server?
bin/kafka-topics.sh --list --bootstrap-server localhost:9092

medium

A. Lists all existing Kafka topics

B. Starts the Kafka server

C. Creates a new topic named 'localhost'

D. Shows Zookeeper status

Solution

1. Step 1: Understand the command purpose

   The command lists topics using the Kafka bootstrap server address.

2. Step 2: Identify output type

   It outputs all existing topics in Kafka, not starting server or creating topics.

3. Final Answer:

   Lists all existing Kafka topics -> Option A

4. Quick Check:

   --list shows topics = Lists all existing Kafka topics [OK]

Hint: Use --list with --bootstrap-server to see topics [OK]

Common Mistakes:

• Thinking it starts Kafka server
• Assuming it creates topics
• Confusing with Zookeeper commands

4. You tried to start Kafka server but got an error saying 'Could not connect to Zookeeper'. What is the likely cause?

medium

A. Kafka server is already running

B. Zookeeper service is not running

C. Topic name is missing

D. Java is not installed

Solution

1. Step 1: Analyze error message

   'Could not connect to Zookeeper' means Kafka cannot reach Zookeeper service.

2. Step 2: Identify cause

   This usually happens if Zookeeper is not started or crashed.

3. Final Answer:

   Zookeeper service is not running -> Option B

4. Quick Check:

   Connection error = Zookeeper not running [OK]

Hint: Check Zookeeper is running before Kafka start [OK]

Common Mistakes:

• Ignoring Zookeeper status
• Assuming Kafka server conflict
• Blaming missing topic name

5. You want to test Kafka by sending messages to a topic named 'test'. Which sequence of commands is correct after starting Zookeeper and Kafka server?

hard

A. Start kafka-console-consumer.sh, then create topic with kafka-topics.sh

B. Only start Zookeeper and produce messages directly

C. Run kafka-server-start.sh twice, then produce messages

D. Create topic with kafka-topics.sh, then produce messages with kafka-console-producer.sh

Solution

1. Step 1: Create the topic first

   You must create the topic 'test' before sending messages to it.

2. Step 2: Use producer to send messages

   After topic creation, use kafka-console-producer.sh to send messages to 'test'.

3. Final Answer:

   Create topic with kafka-topics.sh, then produce messages with kafka-console-producer.sh -> Option D

4. Quick Check:

   Create topic then produce = Create topic with kafka-topics.sh, then produce messages with kafka-console-producer.sh [OK]

Hint: Create topic before producing messages [OK]

Common Mistakes:

• Producing messages before topic creation
• Starting Kafka server twice unnecessarily
• Skipping Kafka server start