A solutions architect needs an RDS deployment that automatically fails over to a synchronized standby in a different Availability Zone within about 1-2 minutes if the primary database instance becomes unavailable, with no application-level read scaling requirement. Which RDS feature should be enabled?
- Multi-AZ deployment
- A read replica in the same Availability Zone
- A read replica promoted to a standalone instance
- RDS Proxy configured with a single endpoint
Why A? And why not the others?
Correct answer: A. Multi-AZ deployment
Multi-AZ deployments maintain a synchronous, physically separate standby copy in a different Availability Zone purely for durability and automatic failover; RDS detects primary failure and flips the DNS endpoint to the standby without requiring an application change, typically completing in one to two minutes, and no read traffic is served from the standby under normal conditions. The option describing a same-AZ read replica is wrong because read replicas replicate asynchronously and exist to offload read traffic, not to provide automatic failover, and placing one in the same Availability Zone as the primary would not protect against an AZ-level outage anyway. The option describing promoting a read replica to standalone is wrong because promotion is a manual, one-way operation that breaks the replication relationship permanently; it cannot be used for automatic, transparent failover. The option describing RDS Proxy with a single endpoint is wrong because RDS Proxy manages connection pooling and can shorten failover time for a database that already has a failover target, but it does not itself create a standby or provide failover capability.
Source: AWS RDS documentation: Multi-AZ deployments