SOA-C02 Auto Scaling group Practice Question
A SysOps Administrator needs to automate the deployment of a three-tier web application on AWS. The application consists of a web tier, application tier, and database tier. The administrator wants to use AWS CloudFormation to provision the infrastructure. Which TWO resources should be included in the CloudFormation template to ensure the application is highly available across multiple Availability Zones?
⚠ Common exam trap
SOA-C02 often tests the distinction between resources that provide HA (ASG, multi-AZ ALB) and resources that are merely supporting infrastructure (NAT Gateway, S3, Route 53) — candidates over-select supporting services thinking they add redundancy.
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
✓
Auto Scaling group
Option A (Auto Scaling group) is correct because it distributes EC2 instances across multiple Availability Zones within a region and automatically replaces unhealthy instances, providing high availability and elasticity for the web and application tiers. Option E (Application Load Balancer) is correct because it is a regional, multi-AZ load balancer that routes traffic to healthy targets in multiple Availability Zones, which is essential for a highly available three-tier architecture. Option B (NAT Gateway) only provides outbound internet access for private subnets and does not by itself deliver multi-AZ high availability. Option C (Amazon S3 bucket) is object storage and is not the mechanism for achieving multi-AZ compute availability. Option D (Amazon Route 53 hosted zone) provides DNS resolution and can support failover routing, but it is not the resource that ensures the application's tiers are highly available across 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.
- ✓
Auto Scaling group
Why this is correct
An Auto Scaling group is capacity management that spans multiple Availability Zones, launching and terminating instances to maintain a desired count and to replace unhealthy ones automatically. By distributing instances across AZs, it ensures that the application tier remains available even if an entire AZ becomes unavailable, providing fault tolerance and elasticity.
- ✗
NAT Gateway
Why it's wrong here
A NAT Gateway provides outbound internet connectivity for instances in private subnets, translating their traffic to a public IP. It does not handle inbound user traffic, nor does it manage instance health or capacity. While a NAT gateway itself is highly available within its AZ, it does not directly support high availability of the web or application tiers in this deployment.
- ✗
Amazon S3 bucket
Why it's wrong here
Amazon S3 is a regional object storage service, not a compute resource. It can host static website content or serve as an asset store, but it cannot run the web or application tier, nor does it provide automatic failover or instance replacement. Therefore, it does not contribute to high availability of the compute layers in this architecture.
- ✗
Amazon Route 53 hosted zone
Why it's wrong here
Incorrect. A Route 53 hosted zone manages DNS records and can be used for routing traffic, but the primary resources for high availability across AZs are the Auto Scaling group and Application Load Balancer. While Route 53 can support DNS-level failover, it is not a direct infrastructure resource within the CloudFormation template for this purpose.
- ✓
Application Load Balancer
Why this is correct
An Application Load Balancer is a regional, Layer 7 load balancer that distributes incoming traffic across targets in multiple Availability Zones. It performs health checks and automatically routes traffic only to healthy instances, working in tandem with the Auto Scaling group to absorb AZ failures and maintain high availability.
Visual reference
Quick reference
AWS S3 Storage Class Comparison
| Storage Class | Min Duration | Retrieval | Use Case |
|---|---|---|---|
| S3 Standard | None | Immediate | Frequently accessed data |
| S3 Standard-IA | 30 days | Immediate | Infrequent access, rapid retrieval |
| S3 One Zone-IA | 30 days | Immediate | Non-critical infrequent data |
| S3 Intelligent-Tiering | None | Immediate–hours | Unknown or changing access patterns |
| S3 Glacier Instant | 90 days | Milliseconds | Archive with instant retrieval |
| S3 Glacier Flexible | 90 days | Minutes–hours | Archive, flexible retrieval |
| S3 Glacier Deep Archive | 180 days | Hours | Long-term compliance archive |
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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 SOA-C02 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 SOA-C02 exam.