The answer is AWS Shield Standard, which provides free DDoS protection for AWS resources automatically at no extra cost. This service is always-on and defends against attacks targeting Layers 3 and 4 of the OSI model, such as SYN floods and UDP reflection attacks, by detecting and mitigating malicious traffic before it reaches your infrastructure. On the AWS Certified Cloud Practitioner CLF-C02 exam, this question tests your understanding of the built-in security services that come with every AWS account—a common trap is confusing Shield Standard with the paid Shield Advanced, which adds cost and Layer 7 protection. Remember that “Standard” means standard-issue for all customers, so if the scenario mentions “no additional charge” and “automatic,” Shield Standard is your answer. A simple memory tip: think of “Standard” as the free, always-on shield that guards the network and transport layers, while “Advanced” is the premium upgrade for deeper application-layer defense.
CLF-C02 Security and Compliance Practice Question
This CLF-C02 practice question tests your understanding of security and compliance. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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.
Which AWS service provides DDoS protection for all AWS customers at no additional charge and automatically protects resources at Layers 3 and 4?
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 automatically enabled for all AWS customers at no additional cost and provides always-on detection and inline mitigation of DDoS attacks targeting Layers 3 (network) and 4 (transport) of the OSI model. It protects common AWS resources such as Amazon CloudFront, Elastic Load Balancing, and Amazon Route 53 from common infrastructure-layer attacks like SYN floods and UDP reflection attacks.
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 at Layer 7 (application layer) and is a paid service, not automatically included.
✗
AWS Shield Advanced
Why it's wrong here
Shield Advanced provides enhanced protections but is a paid service starting at $3,000/month.
✓
AWS Shield Standard
Why this is correct
Shield Standard is included at no charge for all AWS customers and automatically protects against Layer 3/4 DDoS attacks on all AWS resources.
Related concept
Read the scenario before looking for a memorised answer.
✗
Amazon CloudFront with geo-restriction
Why it's wrong here
CloudFront geo-restriction blocks traffic from specific countries but is not a DDoS protection service.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse AWS Shield Standard (free, automatic Layer 3/4 protection) with AWS Shield Advanced (paid, enhanced protection including Layer 7 and cost coverage), or mistakenly think AWS WAF provides Layer 3/4 DDoS protection when it only operates at Layer 7.
Detailed technical explanation
How to think about this question
AWS Shield Standard uses a combination of traffic profiling, anomaly detection, and inline mitigation techniques to filter out malicious traffic at the AWS edge. It leverages the scale of AWS infrastructure to absorb and deflect attacks, such as SYN floods, by using SYN cookies and rate limiting at the network boundary. In a real-world scenario, a customer hosting a web application on Elastic Load Balancing would automatically benefit from Shield Standard's protection against volumetric attacks without any configuration changes.
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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CLF-C02 question in full detail.
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 automatically enabled for all AWS customers at no additional cost and provides always-on detection and inline mitigation of DDoS attacks targeting Layers 3 (network) and 4 (transport) of the OSI model. It protects common AWS resources such as Amazon CloudFront, Elastic Load Balancing, and Amazon Route 53 from common infrastructure-layer attacks like SYN floods and UDP reflection attacks.
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.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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