SAA-C03 Design Resilient Architectures Practice Question
A company hosts a web application on EC2 instances behind an Application Load Balancer (ALB). The application requires high availability across two Availability Zones (AZs). Which architectural design ensures the most resilient traffic distribution?
⚠ Common exam trap
SAA-C03 often tests the misconception that enabling Cross-Zone Load Balancing alone provides high availability, when in fact the underlying compute resources must be distributed across multiple AZs.
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
✓
Place EC2 instances in an Auto Scaling group distributed across two AZs behind the ALB.
High availability across two AZs requires resources to be distributed across both AZs so that the failure of one AZ does not take down the application. An Auto Scaling group spanning two AZs behind an ALB ensures that healthy targets exist in both AZs, and the ALB automatically routes traffic only to healthy targets in each enabled AZ.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Deploy all instances in one AZ and use a Route 53 failover policy to a secondary region.
Why it's wrong here
Relying on a single AZ creates a single point of failure within the region, violating high availability requirements. While multi-region failover provides disaster recovery, it does not address the need for low-latency, resilient local traffic distribution between AZs as requested by the architectural design scope.
- ✗
Use an Auto Scaling group with a single AZ and enable Cross-Zone Load Balancing on the ALB.
Why it's wrong here
Cross-zone load balancing distributes traffic across instances in multiple AZs, but if the single AZ fails, the entire application becomes unavailable. Resilience requires distributing instances across multiple physically separate AZs to ensure that infrastructure failures in one location do not impact the overall application availability.
- ✓
Place EC2 instances in an Auto Scaling group distributed across two AZs behind the ALB.
Why this is correct
Distributing Auto Scaling groups across multiple AZs ensures that if one AZ experiences an outage, instances in the other AZ continue serving traffic. The ALB automatically routes requests to healthy targets across the available zones, maintaining service continuity and ensuring the application remains resilient against localized hardware or power failures.
- ✗
Use a Network Load Balancer (NLB) with static IP addresses for each instance in one AZ.
Why it's wrong here
Static IP addressing provides reachability but does not provide fault tolerance if the AZ housing the instances suffers a failure. Resilience is achieved by decoupling the traffic entry point from specific compute locations, allowing the architecture to survive the loss of an entire data center facility.
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JA
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.