SAA-C03 Design Resilient Architectures Practice Question
A media processing company runs a stateless thumbnail-generation fleet on Amazon EC2 instances behind an Application Load Balancer. The instances store no local state, and the team wants the fleet to survive the loss of an entire Availability Zone without manual intervention. The fleet must also scale out automatically based on CPU. Which combination of AWS services should the solutions architect use to meet these requirements with the LEAST operational overhead?
⚠ Common exam trap
The trap here is assuming a load balancer alone provides Availability Zone resilience, when the compute capacity must also be spread across multiple zones by the Auto Scaling group.
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
✓
An Auto Scaling group configured across multiple Availability Zones with a health check against the load balancer, plus an Application Load Balancer with cross-zone load balancing enabled.
Resilience against an Availability Zone failure for a stateless fleet is achieved by distributing capacity across multiple Availability Zones and letting the Auto Scaling group replace unhealthy instances using load balancer health checks. A single multi-AZ Auto Scaling group behind one Application Load Balancer with cross-zone load balancing delivers this with minimal operational effort, while still supporting CPU-based scaling.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Two independent Auto Scaling groups in separate Availability Zones, each attached to its own Application Load Balancer, with Route 53 failover routing between them.
Why it's wrong here
This works but adds operational overhead: two load balancers, two scaling policies, and Route 53 failover records that must be maintained and tested. The requirement asks for the least operational overhead, and a single multi-AZ Auto Scaling group behind one load balancer achieves the same resilience with far less configuration and fewer moving parts.
- ✗
A single Auto Scaling group pinned to one Availability Zone, with a Network Load Balancer in front and an Amazon Route 53 latency record.
Why it's wrong here
Pinning the Auto Scaling group to one Availability Zone means a zonal failure removes all capacity, so the fleet cannot survive the loss of an AZ. A Network Load Balancer and latency record do not create capacity in another zone, and a latency record is not a health-based failover mechanism for a single-zone fleet.
- ✗
An Amazon ECS cluster on AWS Fargate with tasks placed in one Availability Zone and an Application Load Balancer using sticky sessions.
Why it's wrong here
Placing tasks in a single Availability Zone reintroduces a zonal single point of failure. Sticky sessions route users back to the same task, which does not improve resilience and can concentrate load. This does not satisfy surviving the loss of an entire Availability Zone, and it changes the compute platform unnecessarily.
- ✓
An Auto Scaling group configured across multiple Availability Zones with a health check against the load balancer, plus an Application Load Balancer with cross-zone load balancing enabled.
Why this is correct
Spreading the Auto Scaling group across multiple Availability Zones means capacity remains if one AZ fails, and the ELB health check replaces unhealthy instances automatically. Cross-zone load balancing distributes requests evenly to remaining healthy targets, so the stateless fleet keeps serving traffic without manual action and still scales on CPU.
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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.