Confluent Confluent Certifications CCDAK Questions & Answers

• Question 81:

  Your producer is producing at a very high rate and the batches are completely full each time. How can you improve the producer throughput? (select two)

  A. Enable compression

  B. Disable compression

  C. Increase batch.size

  D. Decrease batch.size

  E. Decrease linger.ms

  F. Increase linger.ms

  Correct Answer: AC

  batch.size controls how many bytes of data to collect before sending messages to the Kafka broker. Set this as high as possible, without exceeding available memory. Enabling compression can also help make more compact batches and increase the throughput of your producer. Linger.ms will have no effect as the batches are already full

• Question 82:

  To transform data from a Kafka topic to another one, I should use

  A. Kafka Connect Sink

  B. Kafka Connect Source

  C. Consumer + Producer

  D. Kafka Streams

  Correct Answer: D

  Kafka Streams is a library for building streaming applications, specifically applications that transform input Kafka topics into output Kafka topics

• Question 83:

  To prevent network-induced duplicates when producing to Kafka, I should use

  A. max.in.flight.requests.per.connection=1

  B. enable.idempotence=true

  C. retries=200000

  D. batch.size=1

  Correct Answer: B

  Producer idempotence helps prevent the network introduced duplicates. More details herehttps://cwiki.apache.org/confluence/display/KAFKA/Idempotent+Producer

• Question 84:

  The rule "same key goes to the same partition" is true unless...

  A. the number of producer changes

  B. the number of kafka broker changes

  C. the number of partition changes

  D. the replication factor changes

  Correct Answer: C

  Increasing the number of partition causes new messages keys to get hashed differently, and breaks the guarantee "same keys goes to the same partition". Kafka logs are immutable and the previous messages are not re-shuffled.

• Question 85:

  When is the onCompletion() method called?

  private class ProducerCallback implements Callback {

  @Override

  public void onCompletion(RecordMetadata recordMetadata, Exception e) {

  if (e != null) {

  e.printStackTrace();

  }

  }

  }

  ProducerRecord record =

  new ProducerRecord<>("topic1", "key1", "value1");

  producer.send(record, new ProducerCallback());

  A. When the message is partitioned and batched successfully

  B. When message is serialized successfully

  C. When the broker response is received

  D. When send() method is called

  Correct Answer: C

  Callback is invoked when a broker response is received.

• Question 86:

  If I want to send binary data through the REST proxy to topic "test_binary", it needs to be base64 encoded. A consumer connecting directly into the Kafka topic A.

  A. "test_binary" will receive

  B. binary data

  C. avro data

  D. json data

  E. base64 encoded data, it will need to decode it

  Correct Answer: B

  On the producer side, after receiving base64 data, the REST Proxy will convert it into bytes and then send that bytes payload to Kafka. Therefore consumers reading directly from Kafka will receive binary data.

• Question 87:

  Which of the following is true regarding thread safety in the Java Kafka Clients?

  A. One Producer can be safely used in multiple threads

  B. One Consumer can be safely used in multiple threads

  C. One Consumer needs to run in one thread

  D. One Producer needs to be run in one thread

  Correct Answer: A

• Question 88:

  How will you find out all the partitions where one or more of the replicas for the partition are not in-sync with the leader?

  A. kafka-topics.sh --bootstrap-server localhost:9092 --describe --unavailable- partitions

  B. kafka-topics.sh --zookeeper localhost:2181 --describe --unavailable- partitions

  C. kafka-topics.sh --broker-list localhost:9092 --describe --under-replicated-partitions

  D. kafka-topics.sh --zookeeper localhost:2181 --describe --under-replicated-partitions

  Correct Answer: C

• Question 89:

  A bank uses a Kafka cluster for credit card payments. What should be the value of the property unclean.leader.election.enable?

  A. FALSE

  B. TRUE

  Correct Answer: A

  Setting unclean.leader.election.enable to true means we allow out-of-sync replicas to become leaders, we will lose messages when this occurs, effectively losing credit card payments and making our customers very angry.

• Question 90:

  How do you create a topic named test with 3 partitions and 3 replicas using the Kafka CLI?

  A. bin/kafka-topics.sh --create --broker-list localhost:9092 --replication-factor 3 --partitions 3 --topic test

  B. bin/kafka-topics-create.sh --zookeeper localhost:9092 --replication-factor 3 --partitions 3 --topic test

  C. bin/kafka-topics.sh --create --bootstrap-server localhost:9092 --replication-factor 3 -- partitions 3 --topic test

  D. bin/kafka-topics.sh --create --bootstrap-server localhost:2181 --replication-factor 3 -- partitions 3 --topic test

  Correct Answer: C

  As of Kafka 2.3, the kafka-topics.sh command can take --bootstrap-server localhost:9092 as an argument. You could also use the (now deprecated) option of --zookeeper localhost:2181.