SAA-C03 Design Resilient Architectures Practice Question
A media company runs a transcoding fleet on Amazon EC2 instances behind an Application Load Balancer in a single Availability Zone. The business requires the workload to survive the loss of that Availability Zone with no manual intervention and minimal downtime. The instances store intermediate files on instance store volumes and the fleet is managed by an Auto Scaling group. Which change should a solutions architect make to meet the requirement?
⚠ Common exam trap
The trap here is assuming that adding more instances inside one Availability Zone provides high availability, when zone-level isolation is what actually protects the workload.
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
✓
Add a second Availability Zone to the Auto Scaling group and configure the Application Load Balancer with subnets in both Availability Zones.
Resilience to an Availability Zone failure requires spreading compute across multiple zones and giving the load balancer subnets in each of those zones. The Auto Scaling group then replaces failed instances in the surviving zone while the load balancer routes only to healthy targets, delivering continuous service without human action.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Increase the desired capacity of the Auto Scaling group so that more instances run in the existing Availability Zone.
Why it's wrong here
Adding capacity inside a single Availability Zone does not provide isolation from a zone-level failure. If that zone becomes unavailable, every instance becomes unreachable at the same time regardless of how many were running. Scaling horizontally within one zone improves throughput but does nothing to satisfy the resilience requirement.
- ✗
Convert the instances to Spot Instances and configure a placement group to keep them close together.
Why it's wrong here
Spot Instances can be reclaimed with little notice and placement groups cluster capacity, which increases correlated failure risk rather than reducing it. Neither change provides protection against the loss of an Availability Zone, and a cluster placement group actually concentrates all instances in a single zone, worsening the exposure.
- ✓
Add a second Availability Zone to the Auto Scaling group and configure the Application Load Balancer with subnets in both Availability Zones.
Why this is correct
Distributing the Auto Scaling group across two Availability Zones and attaching the load balancer to subnets in both zones lets the fleet continue serving traffic if one zone fails. The load balancer health checks remove unhealthy instances automatically, and the group replaces them, so the workload survives the loss without manual action.
- ✗
Enable detailed CloudWatch monitoring and create an alarm that notifies operators when an instance becomes unhealthy.
Why it's wrong here
Monitoring and alarms improve visibility but do not restore service. The requirement explicitly forbids manual intervention and demands survival of a zone outage, so a notification-based response is insufficient. Alarms also cannot move capacity into another Availability Zone, which is the actual need here.
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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.