Apache Kafka Practice Exam 2025 – The Complete All-in-One Guide for Exam Success!

When a NotEnoughReplicasException occurs, it indicates that there are not enough replicas of a partition to fulfill the request due to insufficient in-sync replicas (ISRs). This situation affects the availability and the ability to write new data to the topic, but it does not impact the ability of consumers to read existing data.

Consumers can still access and read messages that have already been stored in the partitions as long as those partitions are available, even if they are not fully replicated at the time of the exception. This ensures that existing data remains accessible for reading, allowing systems dependent on that data continuity to function without disruption while Kafka handles the underlying replication and failure scenarios.

In contrast, when a NotEnoughReplicasException occurs, the topic itself is not deleted, and all data is not lost. While some writing operations may be temporarily affected due to the lack of sufficient replicas, all previously stored messages remain intact unless explicitly deleted. Additionally, replicas do not automatically resync; manual intervention or corrective actions are often required to restore the replication factors or resolve underlying issues leading to the exception.