SAA-C03 Design Resilient Architectures Practice Question
A company is building a serverless application that processes messages from an Amazon SQS queue using AWS Lambda. The application must not lose messages and must handle occasional downstream failures gracefully. The Lambda function sometimes fails due to a transient error in a downstream service. The company wants to ensure that failed messages are retried and eventually processed, but also wants to avoid infinite retries that could block the queue. What should the company do?
⚠ Common exam trap
The trap here is assuming that increasing Lambda timeout or visibility timeout solves the problem of persistent downstream failures, when in fact a DLQ is needed to prevent infinite retries.
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
✓
Configure a dead-letter queue (DLQ) on the source SQS queue and set the maximumReceiveCount to a reasonable value.
Using a dead-letter queue on the source SQS queue with a maximumReceiveCount ensures that messages are retried a limited number of times and then moved to a DLQ for separate handling. This prevents poison messages from blocking the queue and allows for later analysis or reprocessing, meeting the requirement to avoid infinite retries while not losing messages.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Increase the Lambda function's timeout and memory allocation to reduce the chance of transient errors.
Why it's wrong here
Increasing timeout and memory may help performance but does not address the need to handle persistent failures. Messages would still be retried indefinitely if the downstream error persists. There is no mechanism to move failed messages aside, so the queue could become blocked with poison messages.
- ✓
Configure a dead-letter queue (DLQ) on the source SQS queue and set the maximumReceiveCount to a reasonable value.
Why this is correct
Setting a DLQ on the source queue and a maximumReceiveCount allows messages that repeatedly fail to be moved to a separate queue after a set number of attempts. This prevents infinite retries and preserves failed messages for later analysis or reprocessing. Lambda automatically returns messages to the queue if the function fails, so the receive count increments with each attempt.
- ✗
Set the SQS queue's visibility timeout to a very high value so that messages are not retried until the downstream service recovers.
Why it's wrong here
A high visibility timeout delays retries but does not prevent infinite retries or handle poison messages. If the downstream service never recovers, messages remain invisible and may eventually be retried, causing the same failure. This does not provide a way to isolate failed messages and can delay processing of other messages.
- ✗
Configure the Lambda function to write failed messages to an Amazon S3 bucket and delete them from the queue.
Why it's wrong here
This approach requires custom code to handle failures and does not leverage SQS's native retry and DLQ features. It also risks losing messages if the Lambda function itself fails before writing to S3. The solution is more complex and less reliable than using a DLQ.
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.