Acknowledgment modes (acks=0, 1, all) in Kafka - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to set the acknowledgment mode to no acknowledgments (acks=0).

Kafka

props.put("acks", "[1]");

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

A0

B1

Call

D-1

Attempts:

3 left

💡 Hint

Common Mistakes

Using '1' or 'all' instead of '0' for no acknowledgments.

Setting acks to 0 means the producer does not wait for any acknowledgment from the broker.

2fill in blank

medium

Complete the code to set the acknowledgment mode to wait for leader acknowledgment (acks=1).

Kafka

props.put("acks", "[1]");

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

A1

B0

Call

D-1

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing '1' with 'all' or '0'.

Setting acks to 1 means the producer waits for the leader broker to acknowledge the message.

3fill in blank

hard

Fix the error in the code to set acknowledgment mode to wait for all replicas (acks=all).

Kafka

props.put("acks", "[1]");

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

A1

B0

Ctrue

Dall

Attempts:

3 left

💡 Hint

Common Mistakes

Using boolean or numeric values instead of the string 'all'.

The correct value to wait for all replicas is the string "all".

4fill in blank

hard

Fill both blanks to create a producer configuration with acks set to wait for leader and retries set to 3.

Kafka

props.put("acks", "[1]");
props.put("retries", [2]);

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

A1

B0

C3

Dall

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up acknowledgment modes or using string instead of integer for retries.

Setting acks to 1 waits for leader acknowledgment, and retries to 3 allows three retry attempts.

5fill in blank

hard

Fill all three blanks to configure a producer with acks set to all, retries set to 5, and enable idempotence.

Kafka

props.put("acks", "[1]");
props.put("retries", [2]);
props.put("enable.idempotence", [3]);

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

Atrue

Bfalse

C5

Dall

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect types or values for these settings.

Setting acks to all waits for all replicas, retries to 5 allows five retries, and enable.idempotence to true ensures exactly-once delivery.

Practice

1. Which acks mode in Kafka provides the fastest message sending but with the least safety?

easy

A. acks=0

B. acks=1

C. acks=all

D. None of the above

Solution

1. Step 1: Understand acks=0 behavior

   This mode means the producer does not wait for any acknowledgment from the broker, so it sends messages fastest but with no guarantee of delivery.

2. Step 2: Compare with other modes

   acks=1 waits for leader confirmation, and acks=all waits for all replicas, both slower but safer.

3. Final Answer:

   acks=0 -> Option A

4. Quick Check:

   Fastest but least safe = acks=0 [OK]

Hint: No wait for confirmation means fastest mode is acks=0 [OK]

Common Mistakes:

• Confusing acks=0 with acks=1
• Thinking acks=all is fastest
• Assuming acks=0 waits for leader

2. Which of the following is the correct way to set the acknowledgment mode to wait for all replicas in Kafka producer configuration?

easy

A. "acks=1"

B. "acks=0"

C. "acks=all"

D. "ack=all"

Solution

1. Step 1: Recall correct property name and value

   The property is acks (plural), and to wait for all replicas, the value is all.

2. Step 2: Check options for syntax correctness

   "acks=all" uses correct key and value: "acks=all". "ack=all" has a typo "ack" instead of "acks".

3. Final Answer:

   "acks=all" -> Option C

4. Quick Check:

   Wait for all replicas = acks=all [OK]

Hint: Remember plural 'acks' and value 'all' for all replicas [OK]

Common Mistakes:

• Using 'ack' instead of 'acks'
• Confusing 'acks=1' with 'acks=all'
• Setting 'acks=0' for all replicas

3. Consider this Kafka producer code snippet:

props.put("acks", "1");
producer.send(record);
System.out.println("Message sent");

What does acks=1 guarantee before printing "Message sent"?

medium

A. Message is stored only in producer buffer

B. No guarantee; message may be lost

C. All replicas have confirmed the message

D. Leader broker has confirmed the message

Solution

1. Step 1: Understand acks=1 meaning

   This mode waits for the leader broker to confirm the message is received and written to its log.

2. Step 2: Compare with other options

   acks=0 gives no guarantee, acks=all waits for all replicas, and producer buffer storage is unrelated.

3. Final Answer:

   Leader broker has confirmed the message -> Option D

4. Quick Check:

   acks=1 means leader confirmation [OK]

Hint: acks=1 waits for leader confirmation only [OK]

Common Mistakes:

• Thinking acks=1 waits for all replicas
• Assuming no guarantee with acks=1
• Confusing producer buffer with broker confirmation

4. You have this Kafka producer configuration:

props.put("acks", "alll");

What is the problem with this configuration?

medium

A. Typo in the value; should be "all"

B. Typo in the key; should be "ack"

C. No problem; "alll" is valid

D. Should be an integer, not a string

Solution

1. Step 1: Check the value spelling

   The correct value for waiting all replicas is "all", but here it is misspelled as "alll" with an extra 'l'.

2. Step 2: Verify key and value types

   The key "acks" is correct and the value should be a string. So the problem is only the typo in the value.

3. Final Answer:

   Typo in the value; should be "all" -> Option A

4. Quick Check:

   Value must be "all", not "alll" [OK]

Hint: Check spelling of 'all' carefully in acks value [OK]

Common Mistakes:

• Assuming 'alll' is valid
• Changing key to 'ack' instead of 'acks'
• Using integer instead of string for acks

5. You want to ensure maximum data safety in Kafka producer but can tolerate some delay. Which acks setting should you use and why?

hard

A. acks=1 because leader confirmation is enough

B. acks=all because it waits for all replicas

C. acks=0 because it is fastest

D. acks=-1 because it disables acknowledgments

Solution

1. Step 1: Identify safety vs speed tradeoff

   acks=all waits for all replicas to confirm, ensuring maximum data safety but slower performance.

2. Step 2: Evaluate other options

   acks=0 is fastest but unsafe, acks=1 waits only for leader, and acks=-1 is invalid or equivalent to acks=all but less clear.

3. Final Answer:

   acks=all because it waits for all replicas -> Option B

4. Quick Check:

   Max safety = acks=all [OK]

Hint: Max safety means waiting for all replicas: acks=all [OK]

Common Mistakes:

• Choosing acks=0 for safety
• Confusing acks=-1 as disabling acknowledgments
• Thinking leader confirmation is max safety