Quick Answer
The answer is AWS WAF, the correct choice for protecting web applications against SQL injection and cross-site scripting. AWS WAF is a web application firewall that operates at the application layer (Layer 7), allowing you to create custom rules to inspect HTTP/HTTPS requests and block malicious patterns before they reach your Application Load Balancer. On the AWS Certified Security Specialty SCS-C02 exam, this question tests your ability to differentiate between AWS security services: a common trap is confusing AWS WAF with AWS Shield Advanced, which only provides DDoS protection, or with Network Firewall, which filters at the network layer. Remember that for application-layer web exploits like SQLi and XSS, you need a WAF—think "WAF for Web Attacks." A useful memory tip is "WAF watches the web, Shield stops the flood."
This SCS-C02 practice question tests your understanding of infrastructure security. 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.
A company is deploying a multi-tier web application on AWS. The application uses an Application Load Balancer (ALB) to distribute traffic to EC2 instances in private subnets. The security team wants to protect the application from common web exploits like SQL injection and cross-site scripting. Which AWS service should be used?
AWS WAF.
AWS WAF can inspect HTTP requests and block SQL injection and XSS.
AWS Network Firewall.
Why wrong: Network Firewall provides network-layer filtering, not application-layer inspection.
AWS Shield Advanced.
Why wrong: Shield Advanced protects against DDoS attacks, not application-layer exploits.
AWS Security Hub.
Why wrong: Security Hub aggregates security findings, it does not block traffic.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
AWS WAF.
Option A is correct because AWS WAF is a web application firewall that can protect against common web exploits. Option B is wrong because Shield Advanced provides DDoS protection, not application-layer exploits. Option C is wrong because Network Firewall is for network-level filtering, not application-layer. Option D is wrong because Security Hub is a security posture management service, not a protection service.
Key principle: Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
AWS WAF.
AWS Network Firewall.
Why it's wrong here
Network Firewall provides network-layer filtering, not application-layer inspection.
AWS Shield Advanced.
Why it's wrong here
Shield Advanced protects against DDoS attacks, not application-layer exploits.
AWS Security Hub.
Why it's wrong here
Security Hub aggregates security findings, it does not block traffic.
Common exam traps
Subnetting questions often tempt you into counting all addresses. In normal IPv4 subnets, the network and broadcast addresses are not usable host addresses.
Detailed technical explanation
Subnetting questions test whether you can identify the network, broadcast address, usable range, mask and correct subnet. Slow down enough to calculate the block size correctly.
Key takeaway
Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
Real-world example
A media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
What to study next
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related SCS-C02 subnetting questions on CIDR, address ranges, and subnet selection.
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FAQ
Infrastructure Security — This question tests Infrastructure Security — CIDR notation defines the prefix length..
The correct answer is: AWS WAF. — Option A is correct because AWS WAF is a web application firewall that can protect against common web exploits. Option B is wrong because Shield Advanced provides DDoS protection, not application-layer exploits. Option C is wrong because Network Firewall is for network-level filtering, not application-layer. Option D is wrong because Security Hub is a security posture management service, not a protection service.
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related SCS-C02 subnetting questions on CIDR, address ranges, and subnet selection.
CIDR notation defines the prefix length.
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Last reviewed: Jun 20, 2026
This SCS-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 SCS-C02 exam.
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