DVA-C02 Development with AWS Services Practice Question
A developer is deploying a Lambda function that processes messages from an SQS queue. The queue has a batch size of 10. To optimize cost and performance, the developer wants to minimize the number of Lambda invocations while ensuring that all messages are processed within the SQS visibility timeout. Which configuration should the developer use?
⚠ Common exam trap
Test-takers frequently confuse Lambda timeout with SQS visibility timeout, thinking they should be equal or that increasing both is safe, but the key is to keep Lambda timeout shorter to allow timely retries and avoid message duplication.
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 the Lambda function timeout to less than the SQS visibility timeout.
Setting the Lambda function timeout to less than the SQS visibility timeout ensures that the function completes (success or failure) before the message visibility timeout expires. This prevents the message from becoming visible again while the function is still running, which would cause duplicate invocations. If the function fails, the message remains in the queue and becomes visible again after the original visibility timeout, allowing for reprocessing without overlapping executions. This configuration keeps the number of invocations to one per batch for successful processing and avoids unintended duplicates, rather than adding extra retries.
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 the Lambda function timeout to less than the SQS visibility timeout.
Why this is correct
This ensures messages are processed before becoming visible again, reducing duplicate invocations.
- ✗
Increase the SQS visibility timeout to 5 minutes and set Lambda timeout to 5 minutes.
Why it's wrong here
Lambda timeout should be less than visibility timeout to allow for retries.
- ✗
Configure the Lambda function to process messages asynchronously.
Why it's wrong here
SQS is already asynchronous; this doesn't address the visibility timeout issue.
- ✗
Set the Lambda reserved concurrency to 1 to limit concurrent executions.
Why it's wrong here
This would cause throttling and delays, not optimize cost/performance.
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 by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This DVA-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 DVA-C02 exam.