Confluent CCDAK - Confluent Certified Developer for Apache Kafka Certification Examination

The offset in the RecordMetadata object returned by the producerrepresents the position of the record in the partition— i.e., thesequential IDassigned by Kafka once the message is committed.

FromKafka Producer API Documentation:

“The offset is the position of the record in the partition. This is a unique, sequential number assigned by the broker.”

D refers to metadata.partition(), not offset().

B and C are unrelated to how Kafka handles committed offsets.

The ConsumerRebalanceListener lets youhandle partition assignments and revocationsduring rebalances. This is critical for managingoffsets,stateful processing, orexternal transactions.

FromKafka Consumer Rebalance Docs:

“Implementing ConsumerRebalanceListener allows your application to take action before and after partitions are reassigned.”

A is true: It lets your app react when partitionsassigned to the consumer change.

B, C, and D are unrelated to consumer rebalancing directly.

If a key isnot specified, thedefault Kafka partitioner uses round-robinlogic to assign partitions. This leads toeven distributionof messages across all partitions.

FromKafka Producer Design:

“If the key is null, the producer will assign the partition in a round-robin fashion to achieve load balancing.”

There isno error, and partition 0 isnot alwayschosen in this case.

TheStickyAssignortries to minimize partition movement bypreserving existing assignmentsas much as possible while still achieving a balanced assignment. This improvesconsumer stabilityand reduces rebalances.

From theKafka Consumer Assignor Documentation:

“The StickyAssignor attempts topreserve as many existing assignments as possible, which helps minimize partition movement between rebalances.”

RoundRobinAssignor focuses on even distribution, not stability.

RangeAssignor groups partitions by topic and assigns them consecutively, but can lead to imbalances.

PartitionAssignor is an abstract base class, not an assignor used directly.

To increase consumerthroughput, one effective strategy is toincrease the amount of datafetched in each poll by raisingfetch.max.bytesormax.partition.fetch.bytes. This allows each poll to retrieve more records per request, improving processing efficiency.

FromKafka Consumer Config Docs:

“Increasing fetch size allows consumers to retrieve larger batches of messages, improving throughput and reducing request overhead.”

Removing consumers (A) may reduce parallelism.

Manual commit (C) adds complexity, not throughput.

Decreasing session timeout (D) risks unnecessary rebalances.

When amessage keyis specified in Kafka, the producer uses apartitioner(typically the default hash-based partitioner) todeterministically map all records with the same key to the same partition. Kafka guaranteesorder within a partition, so this enables per-key ordering.

FromKafka Producer Concepts:

“If a key is present, the producer will always route records with the same key to the same partition. Kafka preserves the order of records within a partition.”

This is essential for ordered processing and join semantics.

1st:Place the connector's JAR file in the directory specified by plugin.path

2nd:Restart the Kafka Connect cluster

3rd:Verify using REST API (/connector-plugins)

4th:Configure the connector

5th:(Repeat of 4th, duplicate step)

1st → Place the connector’s JAR file in the directory specified by the plugin.path configuration.

2nd → Restart the Kafka Connect cluster.

3rd → Verify that the connector is installed by listing all available connectors using the Kafka Connect REST API (/connector-plugins).

4th → Configure the connector using a JSON or properties file with the necessary settings.

5th → Configure the connector using a JSON or properties file with the necessary settings.

Kafka Connect requires that custom connectors be placed in the directory defined by plugin.path. After restarting the cluster, you can use the REST API to confirm availability and then deploy the connector configuration.

FromKafka Connect Documentation:

“After placing the JAR in the plugin.path, you must restart the Connect cluster to pick it up. Use the /connector-plugins REST endpoint to verify.”

The duplication of configuration is an error in the question options and should occur only once.

The onCompletion() method of Kafka’sCallback interfaceis executedonce the broker acknowledgesthe message. This includes success or failure, and it isinvoked asynchronouslyby the producer.

FromKafka Java Client API Documentation:

“The onCompletion method will be called when the record sent to the server has been acknowledged, or when an error occurs.”

This ensures thatthe record was sent and acknowledged, not just added to a batch or local buffer.