Confluent Confluent Certified Developer CCDAK Questions & Answers

• Question 21:

  When auto.create.topics.enable is set to true in Kafka configuration, what are the circumstances under which a Kafka broker automatically creates a topic? (select three)

  A. Client requests metadata for a topic

  B. Consumer reads message from a topic

  C. Client alters number of partitions of a topic

  D. Producer sends message to a topic

  Correct Answer: ABD

  A kafka broker automatically creates a topic under the following circumstances- When a producer starts writing messages to the topic - When a consumer starts reading messages from the topic - When any client requests metadata for the topic

• Question 22:

  If I want to have an extremely high confidence that leaders and replicas have my data, I should use

  A. acks=all, replication factor=2, min.insync.replicas=1

  B. acks=1, replication factor=3, min.insync.replicas=2

  C. acks=all, replication factor=3, min.insync.replicas=2

  D. acks=all, replication factor=3, min.insync.replicas=1

  Correct Answer: C

  acks=all means the leader will wait for all in-sync replicas to acknowledge the record. Also the min in-sync replica setting specifies the minimum number of replicas that need to be in- sync for the partition to remain available for writes.

• Question 23:

  In Avro, adding an element to an enum without a default is a __ schema evolution

  A. breaking

  B. full

  C. backward

  D. forward

  Correct Answer: A

  Since Confluent 5.4.0, Avro 1.9.1 is used. Since default value was added to enum complex type , the

  schema resolution changed from:

  (<1.9.1) if both are enums:** if the writer's symbol is not present in the reader's enum, then an error is

  signalled. **(>=1.9.1) if both are enums:

  if the writer's symbol is not present in the reader's enum and the reader has a default value, then that value

  is used, otherwise an error is signalled.

• Question 24:

  A consumer sends a request to commit offset 2000. There is a temporary communication problem, so the broker never gets the request and therefore never responds. Meanwhile, the consumer processed another batch and successfully committed offset 3000. What should you do?

  A. Add a new consumer to the group

  B. Use the kafka-consumer-group command to manually commit the offsets 2000 for the consumer group

  C. Restart the consumer

  D. Nothing

  Correct Answer: D

  In this case, because the offset 3000 has been committed and all the messages between 0 and 3000 have all been processed, it is okay not to have committed offset 2000. The right answer is to do "nothing", this behaviour is acceptable

• Question 25:

  What's a Kafka partition made of?

  A. One file and one index

  B. One file

  C. One file and two indexes per segment

  D. One file and two indexes

  Correct Answer: C

  Kafka partitions are made of segments (usually each segment is 1GB), and each segment has two corresponding indexes (offset index and time index)

• Question 26:

  Which of the following Kafka Streams operators are stateful? (select all that apply)

  A. flatmap

  B. reduce

  C. joining

  D. count

  E. peek

  F. aggregate

  Correct Answer: BCDF

  Seehttps://kafka.apache.org/20/documentation/streams/developer-guide/dsl- api.html#statefultransformations

• Question 27:

  A producer application was sending messages to a partition with a replication factor of 2 by connecting to Broker 1 that was hosting partition leader. If the Broker 1 goes down, what will happen?

  A. The producer will automatically produce to the broker that has been elected leader

  B. The topic will be unavailable

  C. The producer will stop working

  Correct Answer: A

  Once the client connects to any broker, it is connected to the entire cluster and in case of leadership changes, the clients automatically do a Metadata Request to an available broker to find out who is the new leader for the topic. Hence the producer will automatically keep on producing to the correct Kafka Broker

• Question 28:

  There are two consumers C1 and C2 belonging to the same group G subscribed to topics T1 and T2. Each of the topics has 3 partitions. How will the partitions be assigned to consumers with Partition Assigner being Round Robin Assigner?

  A. C1 will be assigned partitions 0 and 2 from T1 and partition 1 from T2. C2 will have partition 1 from T1 and partitions 0 and 2 from T2.

  B. Two consumers cannot read from two topics at the same time

  C. C1 will be assigned partitions 0 and 1 from T1 and T2, C2 will be assigned partition 2 from T1 and T2.

  D. All consumers will read from all partitions

  Correct Answer: A

  The correct option is the only one where the two consumers share an equal number of partitions amongst the two topics of three partitions. An interesting article to read ishttps://medium.com/@anyili0928/what-ihave-learned-from-kafka-partition-assignment- strategy-799fdf15d3ab

• Question 29:

  You want to send a message of size 3 MB to a topic with default message size configuration. How does KafkaProducer handle large messages?

  A. KafkaProducer divides messages into sizes of max.request.size and sends them in order

  B. KafkaProducer divides messages into sizes of message.max.bytes and sends them in order

  C. MessageSizeTooLarge exception will be thrown, KafkaProducer will not retry and return exception immediately

  D. MessageSizeTooLarge exception will be thrown, KafkaProducer retries until the number of retries are exhausted

  Correct Answer: C

  MessageSizeTooLarge is not a retryable exception.

• Question 30:

  Select all the way for one consumer to subscribe simultaneously to the following topics - topic.history, topic.sports, topic.politics? (select two)

  A. consumer.subscribe(Pattern.compile("topic\..*"));

  B. consumer.subscribe("topic.history"); consumer.subscribe("topic.sports"); consumer.subscribe ("topic.politics");

  C. consumer.subscribePrefix("topic.");

  D. consumer.subscribe(Arrays.asList("topic.history", "topic.sports", "topic.politics"));

  Correct Answer: AD

  Multiple topics can be passed as a list or regex pattern.