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

The acknowledgment configuration that could lead to message loss is when `acks = 0`. In this configuration, the producer does not wait for any acknowledgment from the broker after sending a message. This means that the producer is not aware if the message has been received, processed, or stored successfully by the broker. As a result, if the broker fails after the message is sent but before it is processed, the message will be lost since there is no confirmation of its arrival.

In contrast, with `acks = 1`, the producer receives an acknowledgment after the leader broker has successfully received the message. This provides a level of assurance against message loss, although it does not guarantee that all replicas receive the message before the acknowledgment is sent. The `acks = all` configuration offers the highest level of durability, as it requires that all in-sync replicas acknowledge receipt of the message, thus minimizing the risk of loss even in situations of broker failures.

The statement that all configurations guarantee message delivery is not accurate, as different configurations provide varying levels of durability and acknowledgment, with `acks = 0` being the least secure option leading to potential message loss.