Apache Kafka Practice Exam 2026 – The Complete All-in-One Guide for Exam Success!

The default Kafka replica setting is considered unsafe when replicas are stored on brokers that are located in the same rack or availability zone (AZ). This is due to the potential risk of a single point of failure. For instance, if all brokers of a particular partition's replicas are housed within the same physical location, such as a rack or AZ, then an event that impacts that entire location, like a power failure or network outage, could result in the loss of access to those replicas. This means that, even if the leader broker remains operational, having all replicas in one place diminishes the reliability of the data because there are fewer copies spread across different physical locations to fall back on in case of a failure.

In contrast, other circumstances presented in the options may present challenges but do not inherently compromise the safety of data replication in the same fundamentally dangerous way. For example, unexpected broker shutdowns might temporarily affect availability but can often be managed with proper configurations for automatic recovery. Similarly, high loads on brokers could lead to performance issues but would not directly cause losses of replicas. Finally, partition deletion is a management operation that would remove data but isn't directly related to the safety of replication in terms of replica placement.