A company runs a web application that accepts customer orders. During peak hours, the order processing component often becomes overloaded, causing orders to be dropped. The company wants to ensure that every order is reliably stored and processed, and that the web tier and the processing tier can scale independently without losing data. Which AWS service should the company use to decouple the application components and provide a durable buffer for incoming orders?
Answer choices
Why each option matters
Good practice is not just finding the correct option. The wrong answers often show the exact trap the exam wants you to fall into.
Best answer
Amazon Simple Queue Service (SQS)
Amazon SQS is a message queue service that reliably stores messages until they are consumed. It decouples the web tier from the processing tier, buffers orders during spikes, and ensures no orders are lost. This makes it the correct choice for this scenario.
Distractor review
Amazon Simple Notification Service (SNS)
Amazon SNS is a pub/sub notification service that pushes messages to subscribers. It does not provide durable storage or buffering; if the subscriber is unavailable, messages may be lost. Therefore, it is not suitable for decoupling with guaranteed processing.
Distractor review
Amazon Kinesis Data Streams
Amazon Kinesis Data Streams is a real-time streaming service designed for ingesting and processing large amounts of data in near real time. While it can handle high throughput, it is overkill for simple order buffering and does not offer the same straightforward decoupling pattern as SQS for point-to-point integration.
Distractor review
AWS Step Functions
AWS Step Functions is a serverless orchestration service that allows you to coordinate multiple AWS services into a workflow. It is not a message queue and does not provide a durable buffer for storing individual order messages until they are processed.
Common exam trap
Common exam trap: NAT rules depend on direction and matching traffic
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Technical deep dive
How to think about this question
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
KKey Concepts to Remember
- Static NAT maps one inside address to one outside address.
- PAT allows many inside hosts to share one public address using ports.
- Inside local and inside global describe the private and translated addresses.
- NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
- Identify inside and outside interfaces first.
- Check whether the scenario needs static NAT, dynamic NAT or PAT.
- Do not confuse NAT matching ACLs with normal packet-filtering intent.
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More questions from this exam
Keep practising from the same exam bank, or move into a focused topic page if this question exposed a weak area.
Question 1
A developer needs to launch a test server for a new application prototype. The developer logs into the AWS Management Console, selects an Amazon EC2 instance type, configures the security group, and starts the instance. The instance is running within two minutes, and the developer did not need to submit a formal request to the company's IT procurement team or wait for approval from a cloud administrator. Which essential characteristic of cloud computing does this scenario best demonstrate?
Question 2
A solutions architect is planning a new web application on AWS. The workload will include 3 Amazon EC2 instances (t3.medium) running 24/7, an Application Load Balancer, and an Amazon RDS for MySQL db.t3.small database. The architect needs to estimate the monthly cost for the first year, considering different purchasing options (On-Demand, 1-year All Upfront Reserved Instance, and Compute Savings Plan). Which AWS tool should the architect use to create this estimate?
Question 3
A company's development team frequently needs temporary test environments. A developer can log into the AWS Management Console, select an Amazon EC2 instance type, configure storage, and launch the instance within minutes without any interaction with the IT infrastructure team. This capability is an example of which essential characteristic of cloud computing?
Question 4
A company's finance team needs to analyze AWS spending in detail. They require a report that includes hourly cost data for each AWS service, each individual resource (e.g., a specific EC2 instance), and any cost allocation tags applied. The team plans to export this data to an Amazon S3 bucket and then import it into a custom business intelligence (BI) analytics dashboard. Which AWS tool should the finance team use to generate this level of detailed cost data?
Question 5
A company uses AWS for its development environment. The finance team wants to set a monthly budget of $10,000. They want to receive an email notification when the actual costs reach 80% of the budget ($8,000) and again when costs exceed the budget. The team needs a managed AWS service that can automatically send these alerts without requiring custom code or third-party tools. Which AWS service should the team use?
Question 6
A company uses AWS Organizations to manage multiple accounts. The security team needs to enforce a policy that restricts SSH access (port 22) from the internet (0.0.0.0/0) in all VPCs across all accounts. The team wants to centrally define the allowed rules and automatically apply them to newly created VPCs and security groups, while also automatically remediating any existing non-compliant security groups. Which AWS service should the team use?
FAQ
Questions learners often ask
What does this CLF-C02 question test?
Static NAT maps one inside address to one outside address.
What is the correct answer to this question?
The correct answer is: Amazon Simple Queue Service (SQS) — Amazon Simple Queue Service (SQS) is a fully managed message queuing service that enables decoupling of application components. It acts as a durable buffer, storing messages (in this case, orders) until they are processed. This ensures no data is lost even during traffic spikes, and it allows the web tier and processing tier to scale independently. Amazon Simple Notification Service (SNS) is a pub/sub messaging service, not a queue; it pushes messages to subscribers and does not provide buffering. Amazon Kinesis is designed for real-time streaming of large data streams, not for decoupling point-to-point processing. AWS Step Functions orchestrates workflows and coordinates state machines but does not provide a durable message buffer.
What should I do if I get this CLF-C02 question wrong?
Then try more questions from the same exam bank and focus on understanding why the wrong options are tempting.
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