- A
AWS WAF
Why wrong: AWS WAF protects against application-layer attacks such as SQL injection and cross-site scripting, not volumetric network-layer DDoS attacks.
- B
AWS Shield Standard
AWS Shield Standard is free and automatically provides always-on protection against common network-layer (Layer 3/4) DDoS attacks for all AWS customers. It requires no configuration or additional cost, meeting the company's requirements.
- C
AWS Shield Advanced
Why wrong: AWS Shield Advanced provides enhanced DDoS protection, including cost protection, access to the DDoS Response Team, and near real-time visibility, but it is a paid service. The company specifically wants a service at no additional cost, so Shield Advanced does not meet that requirement.
- D
AWS Network Firewall
Why wrong: AWS Network Firewall is a managed firewall service that provides stateful inspection, intrusion prevention, and traffic filtering. It is not designed to specifically mitigate DDoS attacks and does not provide always-on, automatic DDoS protection at no cost.
AWS Shield Standard: Free Automatic DDoS Protection
This CLF-C02 practice question tests your understanding of security and compliance. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A company hosts a public-facing web application on Amazon EC2 instances behind an Application Load Balancer. The security team has noticed an increase in volumetric distributed denial-of-service (DDoS) attacks targeting the application's IP address. The company wants a managed AWS service that provides automatic, always-on protection against common network-layer DDoS attacks at no additional cost. Which AWS service should the company use?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"always"Why it matters: Absolute qualifier. An answer using 'always' is only correct if there are genuinely no exceptions — absolute statements are often wrong in networking.
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
AWS Shield Standard
AWS Shield Standard is the correct choice because it provides automatic, always-on protection against common network-layer (Layer 3/4) DDoS attacks, such as SYN floods and UDP reflection attacks, at no additional cost. It is integrated with Elastic Load Balancing (ELB), Amazon CloudFront, and Amazon Route 53, making it ideal for protecting a public-facing web application behind an Application Load Balancer without requiring any configuration or extra fees.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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 protects against application-layer attacks such as SQL injection and cross-site scripting, not volumetric network-layer DDoS attacks.
When this WOULD be correct
When a company needs to protect a web application from common web exploits like SQL injection or cross-site scripting, and requires customizable rules to filter HTTP/S requests, AWS WAF would be the correct answer.
- ✓
AWS Shield Standard
Why this is correct
AWS Shield Standard is free and automatically provides always-on protection against common network-layer (Layer 3/4) DDoS attacks for all AWS customers. It requires no configuration or additional cost, meeting the company's requirements.
Clue confirmation
The clue word "always" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
AWS Shield Advanced
Why it's wrong here
AWS Shield Advanced provides enhanced DDoS protection, including cost protection, access to the DDoS Response Team, and near real-time visibility, but it is a paid service. The company specifically wants a service at no additional cost, so Shield Advanced does not meet that requirement.
When this WOULD be correct
AWS Shield Advanced would be correct if the question specified a need for enhanced protection against sophisticated DDoS attacks, 24/7 access to the DDoS Response Team (DRT), cost protection against scaling charges, or integration with AWS WAF for web-layer attacks, and the company is willing to pay the associated fee.
- ✗
AWS Network Firewall
Why it's wrong here
AWS Network Firewall is a managed firewall service that provides stateful inspection, intrusion prevention, and traffic filtering. It is not designed to specifically mitigate DDoS attacks and does not provide always-on, automatic DDoS protection at no cost.
When this WOULD be correct
A company needs to deploy stateful firewall rules to inspect and filter inbound and outbound traffic at the VPC level, such as blocking traffic from specific IP addresses or enforcing domain-based filtering. The question would specify requirements for deep packet inspection or network traffic filtering beyond DDoS protection.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The CLF-C02 exam frequently reuses these exact scenarios with slightly different constraints.
✓AWS Shield StandardCorrect answer▾
Why this is correct
AWS Shield Standard is free and automatically provides always-on protection against common network-layer (Layer 3/4) DDoS attacks for all AWS customers. It requires no configuration or additional cost, meeting the company's requirements.
✗AWS WAFWrong answer — click to see why▾
Why this is wrong here
AWS WAF is a web application firewall that protects against application-layer attacks (e.g., SQL injection, cross-site scripting), not volumetric network-layer DDoS attacks. The question specifies network-layer DDoS protection, which AWS WAF does not provide.
★ When this WOULD be the correct answer
When a company needs to protect a web application from common web exploits like SQL injection or cross-site scripting, and requires customizable rules to filter HTTP/S requests, AWS WAF would be the correct answer.
Why candidates choose this
Candidates may confuse WAF's DDoS protection capabilities (it can mitigate some application-layer DDoS) with network-layer DDoS protection, or assume any DDoS protection requires WAF.
✗AWS Shield AdvancedWrong answer — click to see why▾
Why this is wrong here
AWS Shield Advanced is a paid service ($3,000/month) and does not provide automatic, always-on protection at no additional cost, which contradicts the question's requirement for no additional cost.
★ When this WOULD be the correct answer
AWS Shield Advanced would be correct if the question specified a need for enhanced protection against sophisticated DDoS attacks, 24/7 access to the DDoS Response Team (DRT), cost protection against scaling charges, or integration with AWS WAF for web-layer attacks, and the company is willing to pay the associated fee.
Why candidates choose this
Candidates may confuse Shield Advanced with Shield Standard, assuming 'Advanced' implies better protection without realizing it incurs additional cost, or they may think all DDoS protection from AWS is free.
✗AWS Network FirewallWrong answer — click to see why▾
Why this is wrong here
AWS Network Firewall is a managed firewall service for VPC traffic inspection and filtering, but it does not provide automatic, always-on DDoS protection at no additional cost. It is not designed to mitigate volumetric DDoS attacks at the network layer.
★ When this WOULD be the correct answer
A company needs to deploy stateful firewall rules to inspect and filter inbound and outbound traffic at the VPC level, such as blocking traffic from specific IP addresses or enforcing domain-based filtering. The question would specify requirements for deep packet inspection or network traffic filtering beyond DDoS protection.
Why candidates choose this
Candidates may confuse Network Firewall with a DDoS protection service because it is a security service that can filter traffic, but they overlook that it lacks the automatic, always-on DDoS mitigation capabilities of AWS Shield Standard.
Analysis generated from the official CLF-C02blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse AWS WAF (Layer 7) with network-layer DDoS protection, or assume Shield Advanced is required for any DDoS protection, when Shield Standard already provides free, automatic coverage for common volumetric attacks at Layer 3/4.
Detailed technical explanation
How to think about this question
AWS Shield Standard uses traffic anomaly detection and mitigation techniques at the AWS edge, leveraging the scale of AWS infrastructure to absorb and deflect attacks. It automatically mitigates common attacks like SYN floods by rate-limiting or dropping malicious packets based on connection tracking, and it protects against UDP reflection attacks by validating source IPs. In a real-world scenario, if an attacker sends a massive SYN flood targeting the ALB's public IP, Shield Standard will automatically trigger mitigation without any manual intervention, ensuring the application remains available.
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.
TExam Day Tips
- 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.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A startup's cloud architect reviews their monthly bill and notices costs are higher than expected for a long-running batch job. Switching from on-demand instances to Reserved Instances — or using Spot/Preemptible VMs — can reduce compute costs by up to 72 %. Questions like this test whether you understand the tradeoffs between commitment, flexibility, and cost across cloud pricing models.
Visual reference
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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FAQ
Questions learners often ask
What does this CLF-C02 question test?
Security and Compliance — This question tests Security and Compliance — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: AWS Shield Standard — AWS Shield Standard is the correct choice because it provides automatic, always-on protection against common network-layer (Layer 3/4) DDoS attacks, such as SYN floods and UDP reflection attacks, at no additional cost. It is integrated with Elastic Load Balancing (ELB), Amazon CloudFront, and Amazon Route 53, making it ideal for protecting a public-facing web application behind an Application Load Balancer without requiring any configuration or extra fees.
What should I do if I get this CLF-C02 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "always". Absolute qualifier. An answer using 'always' is only correct if there are genuinely no exceptions — absolute statements are often wrong in networking.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 11, 2026
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.
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