SAA-C03 Design High-Performing Architectures Practice Question
A SaaS company hosts a REST API on Amazon API Gateway with AWS Lambda proxy integration. The API serves tenants in North America and Europe. European users report high latency, but the Lambda function and its Amazon RDS database must remain in the us-east-1 Region for data residency and cost reasons. The team wants to reduce latency for European users without moving the backend. Which solution meets these requirements?
⚠ Common exam trap
The trap here is assuming that any caching layer reduces latency, when a cache located in the same Region as the backend still forces distant users to make the long round trip.
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
✓
Create an Amazon CloudFront distribution with the API Gateway Regional endpoint as the origin and enable caching for cacheable responses.
CloudFront places edge caches near European users and forwards only cache misses to the API Gateway endpoint in us-east-1. For cacheable API responses, this removes most transatlantic round trips while keeping the Lambda function and RDS database in the required Region. Regional endpoints, stage caching, and Lambda tuning all leave the request path crossing the Atlantic or fail to address the geographic latency.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Enable API Gateway caching on the stage and set a TTL of 300 seconds.
Why it's wrong here
Stage caching stores responses at the API Gateway endpoint, which is still in us-east-1. European users would continue to cross the Atlantic to reach the cache, so latency is not reduced for them. Caching also risks serving stale tenant data unless keys are carefully configured, and it does not solve the geographic distance problem.
- ✓
Create an Amazon CloudFront distribution with the API Gateway Regional endpoint as the origin and enable caching for cacheable responses.
Why this is correct
CloudFront caches responses at edge locations close to European users and forwards cache misses to the API Gateway endpoint in us-east-1. For cacheable API responses, this cuts the transatlantic round trip and reduces load on the backend, while the Lambda function and database stay in us-east-1, satisfying data residency and cost constraints.
- ✗
Increase the Lambda function's memory and provisioned concurrency to reduce execution time.
Why it's wrong here
More memory and provisioned concurrency reduce cold starts and execution duration, but the dominant latency for European users is the network round trip to us-east-1. Improving compute does not shorten the distance the request travels, so this does not address the reported latency and adds cost.
- ✗
Create a second API Gateway Regional endpoint in eu-west-1 and use a Lambda authorizer to route requests.
Why it's wrong here
A Regional endpoint in eu-west-1 still forwards requests to the Lambda function in us-east-1, so the transatlantic round trip remains. A Lambda authorizer adds invocation overhead and does not cache responses. This does not reduce latency for European users and adds complexity without addressing the backend location constraint.
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 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.