Question 1mediummultiple choice
Full question →mediummultiple choiceObjective-mapped
A company hosts a web application on Amazon EC2 instances behind an Application Load Balancer. The security team wants to protect the application from common web attacks such as SQL injection and cross-site scripting (XSS) at the edge, before the requests reach the application. The company wants to use pre-built rule sets maintained by AWS to quickly enable protection, and the solution should be fully managed with no servers to manage. Which AWS service should the company use?
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.
A
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AWS Shield Advanced
AWS Shield Advanced provides enhanced protection against distributed denial-of-service (DDoS) attacks. It is not designed to inspect application-layer payloads for SQL injection or XSS. While it can be used in conjunction with AWS WAF, Shield Advanced alone does not offer the rule-based filtering needed for these specific web exploits.
B
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Amazon GuardDuty
Amazon GuardDuty is a threat detection service that continuously monitors for malicious activity and unauthorized behavior across AWS accounts, workloads, and data sources (e.g., CloudTrail logs, VPC Flow Logs, DNS logs). It does not function as a web application firewall and cannot block specific web requests at the application layer.
C
Best answer
AWS WAF
AWS WAF is a fully managed web application firewall that enables customers to monitor and control HTTP(S) requests to their applications. It provides managed rule groups for common threats like SQL injection and cross-site scripting (XSS). The service integrates seamlessly with Application Load Balancers, allowing traffic to be inspected at the edge before reaching the backend instances, and requires no server management.
D
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AWS Network Firewall
AWS Network Firewall is a managed firewall service that provides network-level filtering for VPC traffic, including stateful and stateless inspection and intrusion prevention. It operates at Layers 3 and 4, not at the application layer (Layer 7). While it can provide some threat protection, it is not designed to inspect application-layer attacks like SQL injection or XSS, and it does not offer the pre-configured web-application rule sets that AWS WAF provides.
Common exam trap
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Technical deep dive
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
- Use explanations to understand the rule behind the answer.
TExam Day Tips
- Underline the problem statement mentally.
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
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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?
Read the scenario before looking for a memorised answer.
What is the correct answer to this question?
The correct answer is: AWS WAF — AWS WAF is a web application firewall service that operates at the application layer (Layer 7). It helps protect web applications from common exploits like SQL injection and XSS by inspecting HTTP(S) requests and blocking malicious traffic. AWS WAF integrates with Amazon CloudFront, Application Load Balancer, and Amazon API Gateway. AWS provides a set of managed rule groups that are pre-configured and maintained by AWS to address common threats, so customers can quickly enable protections without needing to write custom rules. The other services listed serve different security purposes: AWS Shield Advanced provides enhanced DDoS protection; Amazon GuardDuty is a threat detection service that monitors for malicious activity across AWS accounts and workloads; AWS Network Firewall is a managed firewall service for network-level filtering (up to Layer 4). For this requirement of protecting a web application against application-layer attacks using pre-built rule sets, AWS WAF is the correct choice.
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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