CCDAK Exam Dumps - Confluent Certified Developer Questions and Answers

A409 Conflictresponse in Kafka Connect REST API usually means:

The connector name provided already exists (i.e., a connector with that name is already deployed).

The Kafka Connect cluster is temporarily unavailable to accept new tasks due toa rebalance in progress.

From theConfluent Developer documentationand Kafka Connect REST API spec:

“409 – Conflict. The connector name is already in use or the worker group is in the process of rebalancing and cannot complete the request at this time.”

Option A is incorrect because invalid configurations return400 Bad Request, not 409.

Option B is invalid because Kafka Connect does not have a strict concept of "capacity" that prevents connector creation with a 409.

For real-time applications, thekey metric to monitor is consumer lag— the difference between thelatest offset on the brokerand thelast committed offset by the consumer.

FromKafka Monitoring Guide:

“Consumer lag is the most important metric for real-time applications. It tells you how far behind the consumer is from the latest data in Kafka.”

B relates to replication, not client responsiveness.

C tracks group membership stability, not data delay.

D tracks input throughput, not processing latency.

If the consumer fails to send heartbeats in time (due to being slow under load), it is considereddead, causing a rebalance. Increasing session.timeout.ms gives the consumermore time to process messages and send heartbeats, preventing premature removal.

FromKafka Docs > Heartbeats and Failures:

“If the consumer does not send a heartbeat in session.timeout.ms, it is considered dead and the group coordinator will trigger a rebalance.”

Reducing max.poll.records mightslow consumption further. More consumers won’t help since each partition already has a dedicated consumer.

With acks=all, the leader waits formin.insync.replicasto acknowledge the message. Since min.insync.replicas=3, Kafka will only commit the messageonce 3 brokers (leader + 2 followers)confirm they have the message.

FromKafka Documentation > Acks and Durability:

“If acks=all is specified, the producer will wait until the full set of in-sync replicas has acknowledged the record. The minimum number of in-sync replicas is controlled by min.insync.replicas.”

Even though the replication factor is 4, only3 acknowledgments are needed, as defined by min.insync.replicas.

Frequentrebalancesin a consumer group occur when:

Consumers are too slowand miss heartbeats (A), or

Instances crash or restart, triggering group membership changes (D)

FromKafka Consumer Group Coordination Docs:

“If a consumer fails to send a heartbeat in time (due to slowness or crash), it is removed from the group, causing a rebalance.”

Option B (partition mismatch) affectsload balancing, not rebalance frequency.

Option C (broker storage) doesn't trigger consumer rebalances.

To send failed records to adead letter queue (DLQ), you must configure:

errors.tolerance=all: Tells the connector tonot failon errors but handle them (e.g., send to DLQ).

errors.deadletterqueue.topic.name=DLQ-Topic: Specifies the DLQ topic.

errors.deadletterqueue.context.headers.enable=true: Includes error context in message headers.

FromKafka Connect Error Handling Docs:

“Kafka Connect supports directing problematic records to a separate topic (DLQ) using errors.* configs. Headers can include failure metadata.”

Options D, E, F are related tologging, not DLQ behavior.

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.

Unit Testing→ MockProducer

Integration Testing→ Testcontainers

Performance Testing→ Trogdor

Mock Data Generation→ Connect Datagen

MockProducer: Simulates a Kafka producer in unit tests (no real broker interaction).

Testcontainers: Spawns Kafka in Docker forreal environment testing.

Trogdor: Kafka’s built-inperformance load testingframework.

Connect Datagen: Createssample source recordsfor test and demo purposes.

FromKafka Developer Tools Guide:

“Kafka developers commonly use MockProducer for unit tests, Testcontainers for integration, and Trogdor for performance tests.”

A:Kafka batches storecompression metadata in their headers, indicating how the batch was compressed.

B:Compression is controlled via theproducer config compression.type, which defaults to none. Producers explicitly set Gzip or other formats.

FromKafka Producer Docs:

“Compression is done by the producer, and the type is stored in the message batch metadata. The broker does not recompress.”

C is false: messages are serializedbeforecompression.

D is false: messages without keys are distributed acrossmultiple partitions.

C is true: When a new broker is added,no partitions are assigned to itunless you create new topics orreassign existing onesusing kafka-reassign-partitions.sh.

D is true: Kafka brokers arehot-pluggable; no need to stop the cluster when scaling.

FromKafka Operations Guide:

“A newly added broker won’t be assigned partitions until reassignments or new topic creation.”

“Kafka allows dynamic scaling by adding brokers without downtime.”

A is false: Broker IDs must bemanually setunless using dynamic broker registration in KRaft mode.

B is false unless the cluster usesKRaft modeand the broker isspecifically assigneda controller role.