CCDAK Exam Dumps : Confluent Certified Developer for Apache Kafka Certification Examination

Low I/O thread activity with blocked throughput often indicates that producer callbacks are consuming too much time, causing the sender thread to block while waiting for onCompletion() to finish.

From Kafka Producer Performance Guide:

“Expensive logic in callbacks (e.g., I/O or complex computation) can block the sender thread, reducing throughput.”

Compression (A) may slightly impact CPU but not I/O thread usage.

Large batches (B) improve throughput if managed correctly.

A Layer 2 network issue (C) would lead to packet loss, not specifically low callback metrics.

The official Apache Kafka Connect documentation explains that connectors run within the same worker JVM, and all logs are written through the worker’s logging framework (Log4j or Log4j2). To isolate logs for a specific connector, Kafka Connect supports connector-specific logging contexts, which can be routed to separate log files using logging configuration.

By modifying the log4j.properties (or log4j2.xml) file to define a dedicated logger and appender for the connector’s package or class name, you can direct logs from that connector to a separate file. This is the recommended and documented approach for debugging individual connectors in a shared Connect cluster.

Option A is incorrect because there is no generic “enable connector context” switch. Option B may increase verbosity but does not isolate logs per connector. Option D is false; Kafka Connect explicitly supports connector-level log separation through logging configuration.

Therefore, the correct approach is to configure a dedicated log appender for the specific connector.

Using assign() gives manual control over partition assignment. In this mode:

B is true: The application chooses partitions directly without involving the group coordinator.

C is true: Since no group coordination occurs, no rebalancing happens if a consumer dies.

From Kafka Consumer API Docs:

“assign() manually assigns a list of partitions to this consumer. No coordination takes place and no rebalancing is triggered.”

A is false: subscribe() and assign() are mutually exclusive.

D is incorrect: Partitions don't need to be equal across topics.