Confluent Confluent Certified Developer CCDAK Questions & Answers

• Question 11:

  How much should be the heap size of a broker in a production setup on a machine with 256 GB of RAM, in PLAINTEXT mode?

  A. 4 GB

  B. 128 GB

  C. 16 GB

  D. 512 MB

  Correct Answer: A

  In Kafka, a small heap size is needed, while the rest of the RAM goes automatically to the page cache (managed by the OS). The heap size goes slightly up if you need to enable SSL

• Question 12:

  Partition leader election is done by

  A. The consumers

  B. The Kafka Broker that is the Controller

  C. Zookeeper

  D. Vote amongst the brokers

  Correct Answer: C

  The Controller is a broker that is responsible for electing partition leaders

• Question 13:

  What is not a valid authentication mechanism in Kafka?

  A. SASL/GSSAPI

  B. SASL/SCRAM

  C. SAML

  D. SSL

  Correct Answer: C

  Learn more about security herehttps://kafka.apache.org/documentation/#security

• Question 14:

  What is the default port that the KSQL server listens on?

  A. 9092

  B. 8088

  C. 8083

  D. 2181

  Correct Answer: B

  Default port of KSQL server is 8088

• Question 15:

  Which KSQL queries write to Kafka?

  A. COUNT and JOIN

  B. SHOW STREAMS and EXPLAIN statements

  C. CREATE STREAM WITH and CREATE TABLE WITH

  D. CREATE STREAM AS SELECT and CREATE TABLE AS SELECT

  Correct Answer: CD

  SHOW STREAMS and EXPLAIN statements run against the KSQL server that the KSQL client is connected to. They don't communicate directly with Kafka. CREATE STREAM WITH and CREATE TABLE WITH write metadata to the KSQL command topic. Persistent queries based on CREATE STREAM AS SELECT and CREATE TABLE AS SELECT read and write to Kafka topics. Non-persistent queries based on SELECT that are stateless only read from Kafka topics, for example SELECT ,? FROM foo WHERE ,?. Non-persistent queries that are stateful read and write to Kafka, for example, COUNT and JOIN. The data in Kafka is deleted automatically when you terminate the query with CTRL-C.

• Question 16:

  A topic has three replicas and you set min.insync.replicas to 2. If two out of three replicas are not available, what happens when a produce request with acks=all is sent to broker?

  A. NotEnoughReplicasException will be returned

  B. Produce request is honored with single in-sync replica C. Produce request will block till one of the two unavailable partition is available again.

  Correct Answer: A

  With this configuration, a single in-sync replica becomes read-only. Produce request will receive NotEnoughReplicasException.

• Question 17:

  A consumer is configured with enable.auto.commit=false. What happens when close() is called on the consumer object?

  A. The uncommitted offsets are committed

  B. A rebalance in the consumer group will happen immediately

  C. The group coordinator will discover that the consumer stopped sending heartbeats. It will cause rebalance after session.timeout.ms

  Correct Answer: B

  Calling close() on consumer immediately triggers a partition rebalance as the consumer will not be available anymore.

• Question 18:

  What exceptions may be caught by the following producer? (select two)

  ProducerRecord record =

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

  try {

  producer.send(record);

  } catch (Exception e) {

  e.printStackTrace();

  }

  A. BrokerNotAvailableException

  B. SerializationException

  C. InvalidPartitionsException

  D. BufferExhaustedException

  Correct Answer: BD

  These are the client side exceptions that may be encountered before message is sent to the broker, and before a future is returned by the .send() method.

• Question 19:

  To read data from a topic, the following configuration is needed for the consumers

  A. all brokers of the cluster, and the topic name

  B. any broker to connect to, and the topic name

  C. the list of brokers that have the data, the topic name and the partitions list

  D. any broker, and the list of topic partitions

  Correct Answer: B

  All brokers can respond to Metadata request, so a client can connect to any broker in the cluster.

• Question 20:

  Producing with a key allows to...

  A. Ensure per-record level security

  B. Influence partitioning of the producer messages

  C. Add more information to my message

  D. Allow a Kafka Consumer to subscribe to a (topic,key) pair and only receive that data

  Correct Answer: B

  Keys are necessary if you require strong ordering or grouping for messages that share the same key. If you require that messages with the same key are always seen in the correct order, attaching a key to messages will ensure messages with the same key always go to the same partition in a topic. Kafka guarantees order within a partition, but not across partitions in a topic, so alternatively not providing a key which will result in round-robin distribution across partitions - will not maintain such order.