SAP-C02 Design for New Solutions Practice Question
A company is migrating a monolithic e-commerce application to AWS. The application consists of a web tier, an application tier, and a database tier. The company wants to decouple the tiers to improve scalability and resilience. Which AWS service should the company use to send messages from the web tier to the application tier asynchronously?
⚠ Common exam trap
Watch out — candidates often confuse SNS (pub/sub push model) with SQS (queue pull model) for decoupling tiers, but SNS does not provide the buffering and independent consumption needed for asynchronous decoupling between a web tier and an application tier.
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 is the correct choice because it provides a fully managed message queuing service that enables asynchronous communication between decoupled application tiers. The web tier can send messages to an SQS queue, and the application tier can poll and process those messages independently, which improves scalability and resilience by allowing each tier to scale and fail independently.
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
Amazon SNS is a publish-subscribe service that fans messages out to multiple subscribers, but it does not retain messages for a single consumer to poll. The web tier needs point-to-point queuing where the application tier retrieves each message once, which is Amazon SQS's role. SNS suits broadcasting one event to many independent subscribers simultaneously.
- ✗
Amazon Kinesis Data Streams
Why it's wrong here
Kinesis Data Streams is a high-throughput streaming ingestion service requiring consumers to poll shards and manage checkpoints, not a decoupling queue that pushes messages to application-tier workers. It is tempting because it handles asynchronous data flow, and it would be correct for real-time analytics ingestion rather than point-to-point tier decoupling.
- ✗
AWS Step Functions
Why it's wrong here
Step Functions orchestrates multi-step workflows with state transitions and branching, not simple point-to-point message delivery. It is tempting because it coordinates distributed components, and would be correct for a long-running order-fulfilment workflow with retries and human approval steps, but the stem asks only for asynchronous decoupling between two tiers.
- ✓
Amazon SQS
Why this is correct
Amazon SQS lets the web tier enqueue messages that the application tier polls and processes independently, breaking the synchronous coupling between tiers. This satisfies the asynchronous messaging requirement, so a slow or failed application tier no longer blocks the web tier.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This SAP-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 SAP-C02 exam.