SAP-C02 Design for New Solutions Practice Question
A company is designing a new cloud-native application that uses Amazon API Gateway, AWS Lambda, and Amazon DynamoDB. The application handles user authentication using Amazon Cognito User Pools. During a stress test, the team notices that some requests are failing with HTTP 503 (Service Unavailable) errors. The CloudWatch logs show that Lambda functions are being throttled, and the DynamoDB table is experiencing high write throttling. The team needs to resolve these issues while maintaining low latency. Which solution is the MOST effective?
⚠ Common exam trap
Candidates often assume buffering with SQS or caching with DAX will solve throttling, but these add latency or only address reads, not writes, while the correct solution directly manages concurrency and write capacity scaling.
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
✓
Set Lambda reserved concurrency to a value that covers peak load and enable DynamoDB auto scaling with a target utilization of 70%.
Setting Lambda reserved concurrency ensures that the function always has capacity available to handle peak load without being throttled by the account-level concurrency limit, while DynamoDB auto scaling with a target utilization of 70% dynamically adjusts write capacity to match traffic patterns, preventing write throttling. This combination directly addresses both throttling issues without introducing additional latency from buffering or caching layers.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Set Lambda reserved concurrency to a value that covers peak load and enable DynamoDB auto scaling with a target utilization of 70%.
Why this is correct
Reserved concurrency guarantees Lambda capacity; DynamoDB auto scaling adjusts capacity automatically.
- ✗
Use Amazon SQS to buffer requests to Lambda and configure a DynamoDB Accelerator (DAX) cluster for caching.
Why it's wrong here
SQS adds latency and may not meet real-time requirements; DAX caches reads, not writes.
- ✗
Increase the DynamoDB write capacity units to the maximum expected peak and configure Lambda provisioned concurrency.
Why it's wrong here
Manually setting high capacity is not cost-effective; provisioned concurrency adds cost and is not needed for throttling.
- ✗
Replace AWS Lambda with Amazon ECS on Fargate and use an Application Auto Scaling target tracking policy.
Why it's wrong here
Moving to containers adds operational overhead and latency, and does not directly address DynamoDB throttling.
Visual reference
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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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This SAP-C02 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 SAP-C02 exam.