SAA-C03 Design Resilient Architectures Practice Question
A small e-commerce company runs a web application on a single Amazon EC2 instance in one Availability Zone. The instance stores session state locally and the database runs on the same instance. The company wants the application to survive an Availability Zone failure with minimal changes and no data loss for committed orders. Which combination of changes should the architect recommend?
⚠ Common exam trap
The trap here is treating EBS snapshots or instance reboots as high availability, when they only provide backup or recover the same failed Availability Zone.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Move the database to Amazon RDS with a Multi-AZ deployment, place the web tier in an Auto Scaling group across multiple Availability Zones, and store session state in Amazon ElastiCache for Redis.
RDS Multi-AZ keeps a synchronous standby in a second Availability Zone and fails over automatically, protecting committed orders. An Auto Scaling group across AZs maintains the web tier, and externalizing sessions to ElastiCache for Redis removes dependence on a single instance, so the application survives an AZ failure with minimal redesign.
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 an Amazon Machine Image of the instance and configure a weekly cron job to launch a replacement instance in a second Availability Zone if the first fails.
Why it's wrong here
A weekly AMI and cron-based replacement is manual, slow, and cannot meet an Availability Zone failure with no data loss because the local database on the failed instance is gone. Committed orders stored only on that instance are lost, and the recovery time is measured in hours rather than minutes.
- ✗
Attach an additional Amazon EBS volume to the instance and take hourly snapshots to Amazon S3 for disaster recovery.
Why it's wrong here
EBS snapshots provide backup, not high availability. An AZ failure still takes down the instance and its attached volumes, and an hourly snapshot can lose up to an hour of committed orders. Restoring from a snapshot also requires manual steps and a new instance, so recovery is neither automatic nor data-loss free.
- ✓
Move the database to Amazon RDS with a Multi-AZ deployment, place the web tier in an Auto Scaling group across multiple Availability Zones, and store session state in Amazon ElastiCache for Redis.
Why this is correct
Amazon RDS Multi-AZ provides a synchronous standby in another Availability Zone with automatic failover, protecting committed orders. An Auto Scaling group across AZs keeps the web tier available, and ElastiCache for Redis externalizes session state so users are not tied to one instance, delivering resilience with minimal application redesign.
- ✗
Enable detailed monitoring on the EC2 instance and create an Amazon CloudWatch alarm that reboots the instance when the status check fails.
Why it's wrong here
A CloudWatch alarm that reboots the instance cannot help when the entire Availability Zone is unavailable, because the reboot targets the same failed host and AZ. Local session state and the local database remain unavailable, so the application still suffers an outage and committed orders are not protected.
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Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Amazon Web Services exam blueprint
This SAA-C03 practice question is part of Courseiva's free Amazon Web Services certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the SAA-C03 exam.