Changed CCDAK Exam Questions

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.

These three metrics are critical for cluster health:

OfflinePartitionsCount: Indicates partitions without active leaders — a sign of broker failure.

ActiveControllerCount: There should beexactly one active controller. A count ≠ 1 signals controller failure.

UncleanLeaderElectionsPerSec: Tracks leader elections where out-of-sync replicas were selected — risky for data loss.

FromKafka Monitoring Documentation:

“Offline partitions and unclean leader elections should trigger alerts. Also, ensure a single active controller is running.”

A is about topics pending deletion — not critical.

E is a per-topic record metric, not broker-level.

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.

unclean.leader.election.enable=false→ Prevents data loss by only considering in-sync replicas when rebalancing.

replication.factor→ Specifies how many redundant copies of partitions are distributed across brokers.

min.insync.replicas=2→ Sets the standard for the number of partition instances that must keep up with the latest committed message.

unclean.leader.election.enable=false ensures that onlyin-sync replicascan be elected as leaders. If disabled, an out-of-sync replica may become leader, potentially leading to data loss.

replication.factor defineshow many brokerswill maintain copies of each partition, directly impacting durability and availability.

min.insync.replicas determineshow many replicas must acknowledgea write when acks=all is used, enforcing write durability.