SAA-C03 Design Resilient Architectures Practice Question
This SAA-C03 practice question tests your understanding of design resilient architectures. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. A key principle to apply: auto Scaling Groups can span multiple Availability Zones.. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A ticket booking system runs on EC2 instances behind an Application Load Balancer. The design must tolerate the failure of one Availability Zone. What should the Auto Scaling group configuration include? The architecture review board prefers a managed AWS-native control.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Subnets in at least two Availability Zones with health checks enabled
Option A is correct because an Auto Scaling group configured with subnets in at least two Availability Zones ensures that if one AZ fails, the remaining AZ(s) can continue to serve traffic. Health checks on the EC2 instances allow the Auto Scaling group to detect and replace unhealthy instances, maintaining the desired capacity across the surviving AZs. This aligns with the requirement for a managed AWS-native control to tolerate an AZ failure.
Key principle: Auto Scaling Groups can span multiple Availability Zones.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
Subnets in at least two Availability Zones with health checks enabled
Why this is correct
An Auto Scaling group spanning multiple AZs can replace unhealthy instances and maintain capacity during an AZ failure.
Related concept
Auto Scaling Groups can span multiple Availability Zones.
✗
All instances in one larger subnet
Why it's wrong here
One AZ remains a single point of failure.
✗
A Network Load Balancer in one subnet
Why it's wrong here
A load balancer in one AZ does not make the application resilient to AZ failure.
✗
A single EC2 instance with detailed monitoring
Why it's wrong here
Monitoring does not provide redundancy.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates might think a single large subnet or a Network Load Balancer provides AZ resilience, but subnets are AZ-scoped and an NLB is a separate load-balancing component, not an Auto Scaling group configuration setting.
Detailed technical explanation
How to think about this question
Under the hood, an Auto Scaling group distributes instances across the subnets you specify, each tied to a distinct Availability Zone. The group uses EC2 health checks (default: EC2 status checks) or custom ELB health checks to determine instance health; if an instance fails health checks, the group terminates it and launches a new one in a different subnet/AZ to maintain balance. In a real-world scenario, if you configure only one subnet (one AZ), the Auto Scaling group cannot shift traffic to another AZ during a failure, violating the design requirement.
KKey Concepts to Remember
Auto Scaling Groups can span multiple Availability Zones.
Multiple AZs provide fault isolation for high availability.
Health checks enable ASGs to replace unhealthy instances automatically.
Application Load Balancers distribute traffic across multiple AZs.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Auto Scaling Groups can span multiple Availability Zones.
Real-world example
How this comes up in practice
An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.
What to study next
Got this wrong? Here's your next step.
Review auto Scaling Groups can span multiple Availability Zones., then practise related SAA-C03 questions on the same topic to reinforce the concept.
Design Resilient Architectures — This question tests Design Resilient Architectures — Auto Scaling Groups can span multiple Availability Zones..
What is the correct answer to this question?
The correct answer is: Subnets in at least two Availability Zones with health checks enabled — Option A is correct because an Auto Scaling group configured with subnets in at least two Availability Zones ensures that if one AZ fails, the remaining AZ(s) can continue to serve traffic. Health checks on the EC2 instances allow the Auto Scaling group to detect and replace unhealthy instances, maintaining the desired capacity across the surviving AZs. This aligns with the requirement for a managed AWS-native control to tolerate an AZ failure.
What should I do if I get this SAA-C03 question wrong?
Review auto Scaling Groups can span multiple Availability Zones., then practise related SAA-C03 questions on the same topic to reinforce the concept.
What is the key concept behind this question?
Auto Scaling Groups can span multiple Availability Zones.
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Question Discussion
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