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Hello Everyone!
Thanks for raising this. The key detail in the question is that the Aurora cluster has a single DB instance with no Aurora Replicas.
The behavior described in the selected answer applies when an Aurora Replica is already available. In that situation, Aurora can promote the healthy replica to become the new primary during failover and redirect connections accordingly.
However, that is not the configuration described in this question. Because the cluster has no Aurora Replicas, there is no existing DB instance available to promote. If the primary DB instance fails, Aurora instead attempts, on a best-effort basis, to create a replacement DB instance in the same Availability Zone as the original instance.
It is also important to distinguish Aurora’s storage layer from its DB instances. Aurora automatically replicates its storage across multiple Availability Zones, which provides storage durability and fault tolerance. However, those storage copies are not Aurora Replica DB instances and therefore cannot simply be promoted as a new primary.
For this reason, the answer key is correct:
“Aurora will attempt to create a new DB Instance in the same Availability Zone as the original instance, and this is done on a best-effort basis.”
The option about promoting a healthy replica would be correct only if the scenario stated that an Aurora Replica already existed.
We appreciate the feedback, as this is an easy distinction to miss when comparing Aurora’s multi-AZ storage architecture with its DB instance failover behavior.
Regards,
Nikee @ Tutorials Dojo
