CLF-C02 Cloud Technology and Services Practice Question
A retail company's order processing system receives large bursts of orders during flash sales. The order intake API gets overwhelmed because it directly calls a downstream processing service that is slower. The company wants to decouple the API from the processing service so orders are not lost during spikes. Which AWS service should they use?
⚠ Common exam trap
A common mix-up: candidates confuse SNS (push-based pub/sub) with SQS (pull-based queue), assuming any decoupling service works the same, but SNS cannot buffer messages or allow the consumer to control the consumption rate, making it unsuitable for handling bursts from a slower downstream service.
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
Amazon SQS (Simple Queue Service) is the correct choice because it provides a fully managed message queue that decouples the order intake API from the downstream processing service. When the API receives a burst of orders, it can immediately push each order message into an SQS queue, and the processing service can poll and consume messages at its own pace, ensuring no orders are lost even during traffic spikes.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Amazon SNS
Why it's wrong here
SNS is a pub/sub notification service for pushing messages to multiple subscribers simultaneously. It does not store messages for later processing — if a subscriber is unavailable, the message is lost. SQS is the correct choice for durable buffering.
- ✓
Amazon SQS
Why this is correct
SQS is a durable message queue that stores messages until they are processed. The intake API enqueues orders, and the processing service dequeues and processes them at its own pace. Messages persist even if the processor is temporarily unavailable.
- ✗
Amazon EventBridge
Why it's wrong here
Amazon EventBridge is an event bus that uses rules to route events to targets, but it is not a durable message queue for buffering work between an intake service and a processor. If a target is temporarily unavailable, EventBridge retries delivery according to a retry policy and can eventually discard events; it does not hold them for the consumer to poll at its own pace. SQS, by contrast, persists each enqueued order until the processing service sends a DeleteMessage call, which is why SQS is the correct decoupling buffer.
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AWS Step Functions
Why it's wrong here
AWS Step Functions orchestrates distributed applications by coordinating tasks into a state machine, tracking execution state and transitions, but it is not a message buffer between producers and consumers. A Step Functions execution runs a defined workflow from start to finish; it does not accept incoming order records and hold them for a separate processor to retrieve later. To achieve buffering with Step Functions you would still need an SQS queue in front of the workflow, so Step Functions alone does not replace SQS for durable decoupling.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CLF-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 CLF-C02 exam.