CCDAK Exam - Confluent Certified Developer for Apache Kafka Certification Examination

NEW QUESTION 1
We have a store selling shoes. What dataset is a great candidate to be modeled as a KTable in Kafka Streams?

• A. Money made until now
• B. The transaction stream
• C. Items returned
• D. Inventory contents right now

Answer: AC

Explanation:
Aggregations of stream are stored in table, whereas Streams must be modeled as a KStream to avoid data explosion

NEW QUESTION 2
You have a Kafka cluster and all the topics have a replication factor of 3. One intern at your company stopped a broker, and accidentally deleted all the data of that broker on the disk. What will happen if the broker is restarted?

• A. The broker will start, and other topics will also be deleted as the broker data on the disk got deleted
• B. The broker will start, and won't be online until all the data it needs to have is replicated from other leaders
• C. The broker will crash
• D. The broker will start, and won't have any dat
• E. If the broker comes leader, we have a data loss

Answer: B

Explanation:
Kafka replication mechanism makes it resilient to the scenarios where the broker lose data on disk, but can recover from replicating from other brokers. This makes Kafka amazing!

NEW QUESTION 3
There are 3 producers writing to a topic with 5 partitions. There are 5 consumers consuming from the topic. How many Controllers will be present in the cluster?

• A. 3
• B. 5
• C. 2
• D. 1

Answer: D

Explanation:
There is only one controller in a cluster at all times.

NEW QUESTION 4
A Zookeeper ensemble contains 5 servers. What is the maximum number of servers that can go missing and the ensemble still run?

• A. 3
• B. 4
• C. 2
• D. 1

Answer: C

Explanation:
majority consists of 3 zk nodes for 5 nodes zk cluster, so 2 can fail

NEW QUESTION 5
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

Answer: ABD

Explanation:
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

NEW QUESTION 6
What client protocol is supported for the schema registry? (select two)

• A. HTTP
• B. HTTPS
• C. JDBC
• D. Websocket
• E. SASL

Answer: AB

Explanation:
clients can interact with the schema registry using the HTTP or HTTPS interface

NEW QUESTION 7
What is the default port that the KSQL server listens on?

• A. 9092
• B. 8088
• C. 8083
• D. 2181

Answer: B

Explanation:
Default port of KSQL server is 8088

NEW QUESTION 8
In Avro, adding an element to an enum without a default is a schema evolution

• A. breaking
• B. full
• C. backward
• D. forward

Answer: A

Explanation:
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.

NEW QUESTION 9
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"));

Answer: AD

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

NEW QUESTION 10
To get acknowledgement of writes to only the leader partition, we need to use the config...

• A. acks=1
• B. acks=0
• C. acks=all

Answer: A

Explanation:
Producers can set acks=1 to get acknowledgement from partition leader only.

NEW QUESTION 11
Which of the following errors are retriable from a producer perspective? (select two)

• A. MESSAGE_TOO_LARGE
• B. INVALID_REQUIRED_ACKS
• C. NOT_ENOUGH_REPLICAS
• D. NOT_LEADER_FOR_PARTITION
• E. TOPIC_AUTHORIZATION_FAILED

Answer: CD

Explanation:
Both of these are retriable errors, others non-retriable errors. See the full list of errors and their "retriable" status herehttps://kafka.apache.org/protocol#protocol_error_codes

NEW QUESTION 12
Which is an optional field in an Avro record?

• A. doc
• B. name
• C. namespace
• D. fields

Answer: A

Explanation:
doc represents optional description of message

NEW QUESTION 13
Suppose you have 6 brokers and you decide to create a topic with 10 partitions and a replication factor of 3. The brokers 0 and 1 are on rack A, the brokers 2 and 3 are on rack B, and the brokers 4 and 5 are on rack C. If the leader for partition 0 is on broker 4, and the first replica is on broker 2, which broker can host the last replica? (select two)

• A. 6
• B. 1
• C. 2
• D. 5
• E. 3

Answer: BE

Explanation:
When you create a new topic, partitions replicas are spreads across racks to maintain availability. Hence, the Rack A, which currently does not hold the topic partition, will be selected for the last replica

NEW QUESTION 14
A consumer wants to read messages from a specific partition of a topic. How can this be achieved?

• A. Call subscribe(String topic, int partition) passing the topic and partition number as the arguments
• B. Call assign() passing a Collection of TopicPartitions as the argument
• C. Call subscribe() passing TopicPartition as the argument

Answer: B

Explanation:
assign() can be used for manual assignment of a partition to a consumer, in which case subscribe() must not be used. Assign() takes a collection of TopicPartition object as an argument https://kafka.apache.org/23/javadoc/org/apache/kafka/clients/consumer/KafkaConsumer.ht
ml#assign-java.util.Collection-

NEW QUESTION 15
StreamsBuilder builder = new StreamsBuilder();
KStream<String, String> textLines = builder.stream("word-count-input"); KTable<String, Long> wordCounts = textLines
.mapValues(textLine -> textLine.toLowerCase())
.flatMapValues(textLine -> Arrays.asList(textLine.split("\W+")))
.selectKey((key, word) -> word)
.groupByKey()
.count(Materialized.as("Counts"));
wordCounts.toStream().to("word-count-output", Produced.with(Serdes.String(), Serdes.Long()));
builder.build();
What is an adequate topic configuration for the topic word-count-output?

• A. max.message.bytes=10000000
• B. cleanup.policy=delete
• C. compression.type=lz4
• D. cleanup.policy=compact

Answer: D

Explanation:
Result is aggregated into a table with key as the unique word and value its frequency. We have to enable log compaction for this topic to align the topic's cleanup policy with KTable semantics.

NEW 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 consume request is sent to broker?

• A. Data will be returned from the remaining in-sync replica
• B. An empty message will be returned
• C. NotEnoughReplicasException will be returned
• D. A new leader for the partition will be elected

Answer: A

Explanation:
With this configuration, a single in-sync replica is still readable, but not writeable if the producer using acks=all

NEW QUESTION 17
What data format isn't natively available with the Confluent REST Proxy?

• A. avro
• B. binary
• C. protobuf
• D. json

Answer: C

Explanation:
Protocol buffers isn't a natively supported type for the Confluent REST Proxy, but you may use the binary format instead

NEW QUESTION 18
What isn't a feature of the Confluent schema registry?

• A. Store avro data
• B. Enforce compatibility rules
• C. Store schemas

Answer: A

Explanation:
Data is stored on brokers.

NEW QUESTION 19
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

Answer: B

Explanation:
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

NEW QUESTION 20
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.

Answer: A

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

NEW QUESTION 21
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