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 trading dashboard 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 team wants the control to be enforceable during normal operations.
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 B is correct because distributing EC2 instances across at least two Availability Zones (AZs) ensures that if one AZ fails, the Auto Scaling group can maintain capacity in the remaining AZ(s). Enabling health checks allows the group to detect instance failures and automatically replace them, providing fault tolerance. This configuration meets the requirement to tolerate a single AZ failure while remaining enforceable during normal operations.
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.
✗
A single EC2 instance with detailed monitoring
Why it's wrong here
Monitoring does not provide redundancy.
✓
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.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse high availability (spanning multiple AZs) with fault tolerance at the instance level, mistakenly thinking a single instance with monitoring or a single subnet can survive an AZ failure.
Detailed technical explanation
How to think about this question
Under the hood, an Auto Scaling group distributes instances evenly across the specified subnets (each in a different AZ) by default. When health checks are enabled (e.g., ELB health checks), the group monitors instance status and replaces unhealthy ones, ensuring the desired capacity is maintained. In a real-world scenario, if an AZ experiences a power outage, the Auto Scaling group automatically launches new instances in the remaining healthy AZs, provided there is sufficient capacity in those subnets.
KKey Concepts to Remember
Auto Scaling groups can span multiple Availability Zones.
Health checks detect unhealthy instances within an Auto Scaling group.
Instances are automatically replaced in healthy AZs during failures.
Distributing resources across AZs prevents single points of failure.
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 B is correct because distributing EC2 instances across at least two Availability Zones (AZs) ensures that if one AZ fails, the Auto Scaling group can maintain capacity in the remaining AZ(s). Enabling health checks allows the group to detect instance failures and automatically replace them, providing fault tolerance. This configuration meets the requirement to tolerate a single AZ failure while remaining enforceable during normal operations.
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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