SAA-C03 Design Cost-Optimized Architectures Practice Question
A company runs a microservices application on Amazon ECS with AWS Fargate. The tasks run continuously, and the company has committed to a 3-year term. The team wants to reduce Fargate compute cost while keeping the same task definitions and architecture. Which action should a solutions architect take?
⚠ Common exam trap
The trap here is reaching for Fargate Spot because it advertises the lowest rate, while overlooking that continuously running microservices cannot accept Spot interruptions and that Compute Savings Plans already discount Fargate.
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 to cover the Fargate vCPU and memory usage.
Compute Savings Plans cover Fargate usage and provide a discount in exchange for a term commitment, so they lower the vCPU and memory rate without changing task definitions or the ECS architecture. Fargate Spot and EC2 Spot introduce interruption risk unsuitable for continuously running services, and resizing task resources changes the workload rather than the pricing model.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Reduce the task CPU and memory values in the task definition to lower the Fargate rate.
Why it's wrong here
Changing task CPU and memory alters the resource allocation available to the application and may degrade performance or cause task failures. It is not a purchasing-option optimization and does not leverage a commitment discount. The scenario asks for cost reduction without changing task definitions, so resizing resources conflicts with the requirement.
- ✗
Convert the Fargate tasks to EC2 launch type with Spot Instances.
Why it's wrong here
Moving from Fargate to EC2 Spot changes the architecture and introduces interruption risk for continuously running microservices. Spot Instances can be reclaimed, which may disrupt services that must stay available, and the scenario asks to keep the same architecture. This option does not preserve the existing Fargate-based design.
- ✗
Enable Fargate Spot for all tasks to obtain the lowest possible compute rate.
Why it's wrong here
Fargate Spot offers discounted capacity but can be interrupted when AWS needs the capacity back. For microservices that run continuously and must remain available, this introduces unacceptable disruption risk. Fargate Spot is better suited to fault-tolerant, interruption-tolerant workloads, not steady production services.
- ✓
Purchase a Compute Savings Plan to cover the Fargate vCPU and memory usage.
Why this is correct
Compute Savings Plans apply to AWS Fargate usage as well as EC2 and Lambda, so they reduce the effective rate for Fargate vCPU and memory while preserving the existing task definitions. For a continuous 3-year commitment, this is the direct way to lower Fargate compute cost without changing the architecture.
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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.