SAA-C03 Design Cost-Optimized Architectures Practice Question
A small e-commerce company hosts its product catalog on a single Amazon EC2 instance in a public subnet. Traffic is steady and predictable, and the instance runs 24/7. The company wants to reduce its monthly compute bill without changing the architecture or risking availability. Which action should a solutions architect recommend?
⚠ Common exam trap
The trap here is reaching for Spot because the hourly rate is lower, when the availability requirement rules out any interruptible purchasing option.
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 one-year Standard Reserved Instance for the instance.
For a steady, always-on instance that will not change family or Region, a Standard Reserved Instance delivers a substantial discount over On-Demand with no architectural change and no availability risk. It is the simplest, lowest-risk way to cut the monthly compute bill for this predictable workload.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Move the instance to a Spot Instance to take advantage of lower hourly rates.
Why it's wrong here
Spot Instances can be reclaimed by AWS with a two-minute interruption notice, which is unacceptable for a production e-commerce catalog that must stay available. The lower rate does not justify the availability risk for a 24/7 steady workload. Spot is suited to fault-tolerant or stateless batch work, not this scenario.
- ✗
Enable detailed monitoring and create a CloudWatch alarm to stop the instance when traffic is low.
Why it's wrong here
Stopping the instance would take the catalog offline, and traffic is described as steady, so there is no low-traffic window to exploit. Detailed monitoring adds cost rather than reducing it. This action does not address the goal of lowering the compute bill without risking availability.
- ✓
Purchase a one-year Standard Reserved Instance for the instance.
Why this is correct
A Standard Reserved Instance is ideal for a steady, always-on instance that will not change family or Region. It provides a significant discount over On-Demand in exchange for a one- or three-year commitment, and it requires no architectural change. This directly lowers the monthly compute bill while preserving availability.
- ✗
Migrate the workload to a smaller instance type and enable burstable performance.
Why it's wrong here
Resizing to a smaller instance may reduce cost but risks insufficient capacity for a production catalog, and burstable instances accrue CPU credits that can be exhausted under sustained load. This is a performance gamble, not a guaranteed cost reduction. It also changes the instance configuration, which the company wants to avoid.
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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.