SAA-C03 Design Resilient Architectures Practice Question
Exhibit
{
"AWSTemplateFormatVersion": "2010-09-09",
"Resources": {
"WebserverGroup": {
"Type": "AWS::AutoScaling::AutoScalingGroup",
"Properties": {
"AvailabilityZones": ["us-east-1a", "us-east-1b"],
"LaunchTemplate": {
"LaunchTemplateId": {
"Ref": "WebLaunchTemplate"
},
"Version": "1"
},
"MinSize": "2",
"MaxSize": "10",
"DesiredCapacity": "2"
}
}
}
}Refer to the exhibit. A solutions architect reviewed an AWS CloudFormation template used to deploy an Auto Scaling group for a production web application. During an AWS Availability Zone outage in us-east-1, users experienced partial application downtime even though the Auto Scaling group reported instances running. Why is this architecture failing resiliency best practices?
⚠ Common exam trap
SAA-C03 often tests the misconception that 'instances running' means the architecture is resilient — candidates overlook that all instances may be in one AZ, so an AZ outage causes downtime despite the ASG reporting healthy.
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
✓
The Auto Scaling group defines Availability Zones directly instead of referencing subnets across multiple zones.
For an Auto Scaling group to survive an Availability Zone outage, it must launch instances across multiple subnets in different AZs. When the ASG specifies Availability Zones directly (or uses a single subnet), all instances land in one AZ, so an AZ failure takes down the entire fleet even though the ASG still reports 'running' instances in the failed zone. Referencing subnets across multiple AZs lets the ASG rebalance and launch replacements in healthy 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.
- ✗
The Launch Template version is hardcoded to version 1 instead of using $Latest or $Default.
Why it's wrong here
A hardcoded launch template version still deploys instances across the group's subnets, so it does not by itself cause partial downtime during an AZ outage. The failure stems from the group spanning too few Availability Zones or an unbalanced subnet distribution. Pinning a version matters only when a newer template must be rolled out.
- ✓
The Auto Scaling group defines Availability Zones directly instead of referencing subnets across multiple zones.
Why this is correct
Hardcoding Availability Zones rather than referencing subnets across multiple zones prevents the Auto Scaling group from launching replacement instances elsewhere during a zone outage. Referencing multi-AZ subnets satisfies the resiliency constraint, maintaining capacity when one zone fails.
- ✗
The MinSize and DesiredCapacity are set too low to handle sudden spikes in traffic during an outage.
Why it's wrong here
While a minimum size of two instances provides basic high availability, the primary cause of downtime during an AZ outage is the inability to provision replacement instances outside the hardcoded zone list, not just the initial capacity.
- ✗
The Auto Scaling group is missing a health check type configuration set to ELB instead of EC2.
Why it's wrong here
While setting the health check type to ELB improves application-level health monitoring, it is not the primary root cause preventing the Auto Scaling group from surviving an entire Availability Zone outage in this template configuration.
Visual reference
About these practice questions
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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.