SAA-C03 Design Cost-Optimized Architectures Practice Question
An application processes data in bursts, running for 30 seconds every few minutes. The workload is unpredictable. Which compute service offers the most cost-effective solution?
⚠ Common exam trap
Candidates might choose ECS or EC2 with auto scaling, ignoring that very short, bursty execution times make a fully serverless function approach significantly more cost-effective.
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
✓
AWS Lambda
AWS Lambda is a serverless compute service that bills based on the number of requests and the duration of execution in milliseconds. For short-lived, bursty, and unpredictable workloads, Lambda is more cost-effective than provisioning servers that would sit idle for the majority of the time between processing events.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Amazon EC2 with Auto Scaling
Why it's wrong here
EC2 instances are billed per second with a minimum of 60 seconds. In a bursty scenario where the task only lasts 30 seconds, an EC2 instance would likely spend more time booting up and shutting down than doing work. Even with Auto Scaling, the overhead and idle time make it less efficient than serverless.
- ✓
AWS Lambda
Why this is correct
Lambda is perfectly suited for this pattern because you are only charged when the code is actually running. Since the task only takes 30 seconds and occurs sporadically, Lambda eliminates the cost of idle infrastructure, providing significant savings over any solution that requires maintaining running servers or containers 24/7.
- ✗
AWS Fargate
Why it's wrong here
Fargate is a serverless container service, but it is generally better for tasks that run for longer periods (minutes to hours). For a 30-second task, the time required to pull the container image and start the task would be inefficient, and the billing granularity is not as fine as Lambda's millisecond-based model.
- ✗
Amazon EC2 Spot Instances
Why it's wrong here
While Spot Instances are cheap, they are not designed for tasks that only last 30 seconds. The overhead of provisioning an instance, waiting for it to be available, and managing the application lifecycle for such a short duration is impractical. Lambda provides better cost-efficiency and much lower operational complexity for this specific use case.
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 |
About these practice questions
Courseiva writes every SAA-C03 question from scratch — 149 in total, each with an explanation and a wrong-answer breakdown. None are copied from real exams or dumps. Learn why practice questions differ from exam dumps →
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.