Confluent Confluent Certified Developer CCDAK Questions & Answers

• Question 41:

  An ecommerce wesbite sells some custom made goods. What's the natural way of modeling this data in Kafka streams?

  A. Purchase as stream, Product as stream, Customer as stream

  B. Purchase as stream, Product as table, Customer as table

  C. Purchase as table, Product as table, Customer as table

  D. Purchase as stream, Product as table, Customer as stream

  Correct Answer: B

  Mostly-static data is modeled as a table whereas business transactions should be modeled as a stream.

• Question 42:

  You are building a consumer application that processes events from a Kafka topic. What is the most important metric to monitor to ensure real-time processing?

  A. UnderReplicatedPartitions

  B. records-lag-max

  C. MessagesInPerSec

  D. BytesInPerSec

  Correct Answer: B

  This metric shows the current lag (number of messages behind the broker)

• Question 43:

  Kafka is configured with following parameters - log.retention.hours = 168 log.retention.minutes = 168 log.retention.ms = 168 How long will the messages be retained for?

  A. Broker will not start due to bad configuration

  B. 168 ms

  C. 168 hours

  D. 168 minutes

  Correct Answer: B

  If more than one similar config is specified, the smaller unit size will take precedence.

• Question 44:

  There are five brokers in a cluster, a topic with 10 partitions and replication factor of 3, and a quota of producer_bytes_rate of 1 MB/sec has been specified for the client. What is the maximum throughput allowed for the client?

  A. 10 MB/s

  B. 0.33 MB/s

  C. 1 MB/s

  D. 5 MB/s

  Correct Answer: D

  Each producer is allowed to produce @ 1MB/s to a broker. Max throughput 5 * 1MB, because we have 5 brokers.

• Question 45:

  What is the risk of increasing max.in.flight.requests.per.connection while also enabling retries in a producer?

  A. At least once delivery is not guaranteed

  B. Message order not preserved

  C. Reduce throughput

  D. Less resilient

  Correct Answer: B

  Some messages may require multiple retries. If there are more than 1 requests in flight, it may result in messages received out of order. Note an exception to this rule is if you enable the producer settingenable.idempotence=true which takes care of the out of ordering case on its own. Seehttps:// issues.apache.org/jira/browse/KAFKA-5494

• Question 46:

  By default, which replica will be elected as a partition leader? (select two)

  A. Preferred leader broker if it is in-sync and auto.leader.rebalance.enable=true

  B. Any of the replicas

  C. Preferred leader broker if it is in-sync and auto.leader.rebalance.enable=false

  D. An in-sync replica

  Correct Answer: BD

  Preferred leader is a broker that was leader when topic was created. It is preferred because when partitions are first created, the leaders are balanced between brokers. Otherwise, any of the in-sync replicas (ISR) will be elected leader, as long as unclean.leader.election=false (by default)

• Question 47:

  In Java, Avro SpecificRecords classes are A. automatically generated from an Avro Schema

  B. written manually by the programmer

  C. automatically generated from an Avro Schema + a Maven / Gradle Plugin

  Correct Answer: C

  SpecificRecord is created from generated record classes

• Question 48:

  You are sending messages with keys to a topic. To increase throughput, you decide to increase the number of partitions of the topic. Select all that apply.

  A. All the existing records will get rebalanced among the partitions to balance load

  B. New records with the same key will get written to the partition where old records with that key were written

  C. New records may get written to a different partition

  D. Old records will stay in their partitions

  Correct Answer: CD

  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 49:

  What is the protocol used by Kafka clients to securely connect to the Confluent REST Proxy?

  A. Kerberos

  B. SASL

  C. HTTPS (SSL/TLS)

  D. HTTP

  Correct Answer: C

  TLS - but it is still called SSL.

• Question 50:

  We want the average of all events in every five-minute window updated every minute. What kind of Kafka Streams window will be required on the stream?

  A. Session window

  B. Tumbling window

  C. Sliding window

  D. Hopping window

  Correct Answer: D

  A hopping window is defined by two propertiesthe window's size and its advance interval (aka "hop"), e.g., a hopping window with a size 5 minutes and an advance interval of 1 minute.