SAA-C03 Design Cost-Optimized Architectures Practice Question
A media company runs a 24/7 recommendation engine on EC2 in one AWS Region. The workload is interruption-intolerant, and the team expects steady usage but may change instance families and sizes during planned optimizations. Compared to the current On-Demand setup, they want the lowest cost while avoiding the rigidity of locking to a specific instance type.
What should the solutions architect recommend?
⚠ Common exam trap
Candidates often confuse Reserved Instances with Savings Plans, assuming a Standard Reserved Instance is the only way to get significant discounts, but the question explicitly requires flexibility to change instance families, which a Compute Savings Plan provides while a Standard Reserved Instance does not.
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
✓
Purchase a Compute Savings Plan for the expected steady hourly usage in that Region.
A Compute Savings Plan offers the lowest cost for steady-state usage without locking to a specific instance type, providing up to 66% discount over On-Demand while allowing flexibility to change instance families, sizes, OS, or tenancy within a Region. This matches the requirement for cost savings with instance flexibility during planned optimizations.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Switch the instances to Spot Instances and use interruption handling because it is the largest discount.
Why it's wrong here
Spot Instances provide strong discounts, but interruption tolerance is required, which the workload lacks.
- ✓
Purchase a Compute Savings Plan for the expected steady hourly usage in that Region.
Why this is correct
Compute Savings Plans discount the usage while allowing flexibility across instance families and sizes in the Region.
- ✗
Purchase a Standard Reserved Instance tied to a single specific instance type for the next 3 years.
Why it's wrong here
Standard RIs can reduce cost, but they are less flexible when the team needs instance-type changes.
- ✗
Keep On-Demand and rely on Auto Scaling to reduce capacity when utilization is low.
Why it's wrong here
Auto Scaling can help, but for interruption-intolerant 24/7 usage it usually cannot match Savings Plans.
Quick reference
Cloud Service Model Comparison
| Model | You Manage | Provider Manages | Examples |
|---|---|---|---|
| IaaS | OS, runtime, apps, data | Hardware, hypervisor, networking | EC2, Azure VMs, GCP Compute Engine |
| PaaS | Apps and data | OS, runtime, middleware, hardware | Elastic Beanstalk, Azure App Service |
| SaaS | Data and settings only | Everything else | Microsoft 365, Salesforce, Workday |
| FaaS / Serverless | Function code only | Infra, scaling, runtime | Lambda, Azure Functions, Cloud Run |
| CaaS | Containers and apps | Kubernetes, OS, hardware | EKS, AKS, GKE |
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.