SAA-C03 Design Resilient Architectures Practice Question

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✗

  Create a read replica in another Availability Zone and promote it manually if needed.

  Why it's wrong here

  A read replica in another Availability Zone provides an asynchronous copy of the database, but it is not a primary DB instance and does not participate in automatic failover. If the source AZ fails, you must manually detect the outage, promote the replica, and reconfigure the application to point to the new endpoint. This operational intervention introduces minutes of downtime, which violates the 'database must continue serving' requirement that expects automatic recovery. Moreover, asynchronous replication means that the replica may lag behind the primary, so promoting it can result in data loss.

  When this WOULD be correct

  This option would be correct if the question required offloading read traffic from the primary database to reduce load, with the ability to promote the replica for disaster recovery, but without a strict requirement for automatic failover.

• ✓

  Modify the DB instance to use a Multi-AZ deployment.

  Why this is correct

  A Multi-AZ RDS deployment provides synchronous standby replication in another Availability Zone and automatic failover if the primary AZ becomes unavailable. This directly matches the requirement to keep the database serving after an AZ failure. It is the simplest resilient design change when the application needs high availability rather than just backups.

• ✗

  Increase the automated backup retention period to 30 days.

  Why it's wrong here

  Automated backups capture consistent snapshots and transaction logs in Amazon S3, but they are designed for point-in-time recovery, not high availability. When an AZ fails, the existing DB instance becomes unavailable, and simply having backups does not provide a running database endpoint or an automatic failover mechanism. You would have to manually restore the instance in another AZ, which takes time (often 10-20+ minutes), during which the database is not serving traffic. Thus, increasing backup retention to 30 days improves durability and recovery granularity but does not keep the database online during an AZ failure.

  When this WOULD be correct

  If the question were about meeting a compliance requirement to retain daily backups for 30 days for audit purposes, then increasing the automated backup retention period to 30 days would be the correct answer.

• ✗

  Resize the DB instance to a larger class.

  Why it's wrong here

  Resizing to a larger DB instance class changes the compute and memory resources of the same single instance, which remains located in one Availability Zone. This choice does not introduce any redundancy and does not alter the failure domain; if the AZ hosting the DB instance goes down, the larger instance also goes down. While a larger instance might absorb more load or handle a higher connection count, it cannot provide failover or continuity of service across AZ boundaries. Therefore, the database would still have a single point of failure at the AZ level.

  When this WOULD be correct

  This option would be correct in a scenario where the database is experiencing performance bottlenecks due to insufficient compute or memory resources, and the question asks for a solution to improve performance without changing the architecture.

Option-by-option analysis

Why each answer is right or wrong

Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The SAA-C03 exam frequently reuses these exact scenarios with slightly different constraints.

Analysis generated from the official SAA-C03blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”

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