Free Confluent Certified Developer for Apache Kafka Certification Examination Practice Questions

Comprehensive and Detailed Explanation From Exact Extract:

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C.  

From Kafka Documentation:

"The isolation.level setting controls whether the consumer will read only committed messages or all messages, including uncommitted messages from ongoing or aborted transactions."

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D.  

From Kafka Internals:

“Kafka stores the state of active and completed transactions in an internal topic called __transaction_state.”

C is true: When a new broker is added, no partitions are assigned to it unless you create new topics or reassign existing ones using kafka-reassign-partitions.sh.

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

From Kafka 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 be manually set unless using dynamic broker registration in KRaft mode.

B is false unless the cluster uses KRaft mode and the broker is specifically assigned a controller role.

fetch-rate: Measures how frequently consumers fetch data — critical for monitoring throughput.

incoming-byte-rate: Shows how much data is being written to the broker per second — a key producer-side metric.

From Kafka JMX Metrics Guide:

“fetch-rate, incoming-byte-rate, request-latency are key performance metrics for producers and consumers.”

B, C, E, and F are application-layer business metrics, not Kafka performance metrics.

The Kafka Streams DSL provides three primary abstractions:

KStream: Represents an unbounded stream of records (append-only).

KTable: Represents a changelog stream where each key has the latest value (like a materialized view).

GlobalKTable: A fully replicated version of KTable across all stream instances, enabling global joins.

From Kafka Streams Developer Guide:

“Kafka Streams provides three core abstractions: KStream, KTable, and GlobalKTable, each serving different purposes in stream processing and joins.”

GlobalKStream and StreamTable do not exist in Kafka’s API.