SAA-C03 Design Resilient Architectures Practice Question
A warehouse integration service receives bursts of orders that sometimes overwhelm a downstream fulfilment service. The architecture must absorb spikes and retry processing without losing requests. Which service should be placed between the web tier and fulfilment workers?
⚠ Common exam trap
It's easy for candidates to confuse load-balancing or caching services (like Route 53 or CloudFront) with message queuing, failing to recognize that only a durable queue like SQS provides the necessary buffering, decoupling, and retry semantics for asynchronous order processing.
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
✓
Amazon SQS queue
Amazon SQS is the correct choice because it acts as a durable, fully managed message queue that decouples the web tier from the fulfilment workers. It can absorb bursts of orders by storing messages durably, and workers can poll the queue at their own pace, with built-in retry logic via visibility timeouts and dead-letter queues to ensure no requests are lost.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
AWS WAF
Why it's wrong here
AWS WAF is a managed web application firewall that inspects HTTP(S) requests for SQL injection, cross-site scripting, and IP reputation rules before they reach resources like CloudFront, ALB, or API Gateway. It is designed to filter or block malicious traffic, not to store or buffer incoming order data. WAF has no internal queue or visibility-timeout mechanism, so a sudden burst of legitimate orders would pass straight through to the integration service and still overwhelm it.
- ✗
Amazon Route 53 weighted routing
Why it's wrong here
Amazon Route 53 weighted routing policy lets you associate a numeric weight with each resource record set, so DNS queries are distributed across multiple endpoints in a specified proportion. However, this only controls which IP address a client resolves initially; after that, resolvers cache the DNS answer for the TTL and traffic flows directly to the chosen target. Weighted routing spreads load but cannot store orders or retry failed deliveries, so it does not smooth out a spike in backend processing demand.
- ✓
Amazon SQS queue
Why this is correct
Amazon SQS is a fully managed message queue that decouples the warehouse integration service from order-producing applications. Producers enqueue each order, and consumers poll for messages at their own pace, allowing the queue to absorb sudden bursts and hold messages until processing capacity is available. Visibility timeout temporarily hides in-flight messages to prevent duplicate processing, while a dead-letter queue captures messages that repeatedly fail, enabling safe retries and preserving the order data during transient outages.
- ✗
Amazon CloudFront
Why it's wrong here
Amazon CloudFront is a content delivery network that caches static and dynamic content at edge locations to reduce latency and offload origin traffic. It excels at accelerating web delivery, but it does not provide a durable message buffer or a mechanism for a backend to pull work at its own rate. Requests that are not cached are immediately proxied to the origin, and CloudFront has no way to store an order payload for later asynchronous processing, so it cannot absorb a burst of orders in this integration workflow.
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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.