SAA-C03 Design Resilient Architectures Practice Question
A content publishing system uses Lambda functions that call an unreliable third-party API. Failed events must be retained for later investigation after retries are exhausted. What should be configured? The design must avoid adding custom operational scripts.
⚠ Common exam trap
It's easy for candidates to confuse a DLQ with other error-handling mechanisms like CloudFront error pages or reserved concurrency, but only a DLQ or failure destination directly captures failed asynchronous Lambda events without custom code.
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
✓
A Lambda dead-letter queue or failure destination
A Lambda dead-letter queue (DLQ) or failure destination is the correct solution because it captures events that have exhausted all retry attempts from an asynchronous Lambda invocation. This allows failed events to be retained in an Amazon SQS queue or SNS topic for later investigation, without requiring custom operational scripts. The DLQ or failure destination integrates directly with Lambda's built-in retry behavior, ensuring that only events that fail after the configured number of retries are sent to the destination.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Lambda reserved concurrency set to zero
Why it's wrong here
Setting reserved concurrency to zero immediately throttles all invocations, so the function never executes and asynchronous events are retried for up to six hours before being dropped if no DLQ is configured. It cannot be used to preserve failed events because it prevents processing entirely rather than routing failures to a durable destination.
- ✗
A larger deployment package
Why it's wrong here
Increasing the deployment package size affects Lambda cold start latency, resource usage, and the package size limit (250 MB unzipped), but it has no impact on invocation orchestration or event-failure handling. Failed asynchronous invocations are retried according to Lambda's retry policy and require an explicit DLQ or failure destination to be captured; a larger package does not create or enable any such mechanism.
- ✗
CloudFront error pages
Why it's wrong here
CloudFront custom error pages simply replace the HTTP response for error status codes returned by an origin, such as 4xx or 5xx; they operate only within the synchronous request/response path. Lambda asynchronous invocation retries and failure destinations are managed by the Lambda service itself, not as HTTP responses, so CloudFront never sees events that fail inside an async handler. Thus custom error pages cannot intercept or save failed Lambda events.
- ✓
A Lambda dead-letter queue or failure destination
Why this is correct
Configuring a Lambda dead-letter queue (SQS or SNS) or an on-failure destination for asynchronous invocations ensures that events that exhaust Lambda's retry policy are captured and stored. Lambda sends the failed event payload to the chosen DLQ or destination, allowing downstream consumers to analyze, quarantine, or reprocess it. This is the standard, built-in mechanism for persisting asynchronous invocation failures.
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 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.