Apache Kafka Practice Exam 2025 - Free Apache Kafka Practice Questions and Study Guide

When a replica fails to fetch messages from the leader for an extended period, it is marked as out of sync. This marking indicates that the replica is not keeping up with the leader in terms of message availability, which could result from various factors such as network issues, higher load, or resource constraints on the broker where the replica resides.

Being marked as out of sync is significant because it helps maintain the overall health and performance of the Kafka cluster. It allows the system to quickly identify which replicas are lagging and take necessary actions, such as promoting a new replica or triggering rebalances to ensure that the data remains consistent and available.

Other options do not accurately reflect the behavior of Kafka under these circumstances. For instance, marking a replica as in-sync would inaccurately suggest that it is effectively receiving and processing messages as expected. Similarly, the notion of automatically removing it from the broker or making it inactive temporarily does not align with Kafka's management of replica states, which prioritizes ensuring replicas can catch up and be reintegrated as needed.