An RDS Multi-AZ DB cluster runs one writer and two readable standby instances, each in a different Availability Zone. When the writer fails, what failover time does AWS state for this deployment?
Show answer and explanation
Answer: B
An RDS Multi-AZ DB cluster with two readable standbys promotes a standby automatically when the writer fails. AWS states that failover typically completes in under 35 seconds, substantially faster than the older single-standby Multi-AZ instance deployment. The cluster endpoints are updated to point at the new writer, so applications can reconnect without configuration changes.
Why the other options are wrong
- A. Rebuilding a standby is not part of cluster failover. The existing readable standbys are promoted, so the outage does not last a quarter of an hour.
- C. A one-hour delay is far beyond the stated design. Automatic promotion of a standby completes in seconds, not an hour.
- D. Automatic failover is the built-in behavior for Multi-AZ DB clusters. Manual failover can be triggered for testing, but it is not the only way the cluster recovers.