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

During a leader election in Apache Kafka, the system may go through a transition period where a new leader is chosen for a partition after the existing leader becomes unavailable. This process can lead to potential message loss for producers that are attempting to send data to that partition during the transition phase.

When the leader fails or is unable to perform its duties, Kafka's architecture requires that a new leader be elected from the remaining in-sync replicas. While this election is occurring, producers trying to write to the partition may not be able to do so successfully, which can result in messages being lost if they do not have a mechanism in place to ensure delivery (such as retries). Therefore, during the brief period of this election, there's a risk that messages intended for the partition may not be persisted.

This aspect highlights the importance of understanding Kafka's mechanisms around partition leadership and how they impact message delivery reliability during failover scenarios. The elimination of leaders, reassignment of responsibilities, and the time required to ensure that all replicas are in sync are critical factors that can lead to message loss in transitional scenarios, thus validating that producers may indeed lose messages during a leader election.