easyMultiple Choice
CAS-004 WAF benefit Practice Question
Which of the following is a primary benefit of using a Web Application Firewall (WAF) in front of a web application?
⚠ Common exam trap
CompTIA often tests the misconception that a WAF provides comprehensive protection against all attacks, when in fact it is a specialized Layer 7 filter that cannot prevent network-layer attacks, business logic abuse, or vulnerabilities in the application's own code logic.
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
✓
It filters malicious HTTP requests and can block common web exploits
A Web Application Firewall (WAF) operates at Layer 7 (application layer) of the OSI model and inspects HTTP/HTTPS traffic for malicious payloads. It uses a combination of signature-based detection, behavioral analysis, and rule sets (e.g., OWASP ModSecurity Core Rule Set) to filter out common web exploits such as SQL injection, cross-site scripting (XSS), and path traversal. By intercepting and blocking malicious requests before they reach the web application, a WAF provides a critical layer of defense without requiring changes to the application code.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
It encrypts all traffic between client and server
Why it's wrong here
A WAF inspects and filters HTTP requests against rule sets, blocking injection and cross-site scripting; it does not terminate TLS or encrypt traffic, which is handled by HTTPS certificates. It is tempting because WAFs sit inline on the web path, so administrators assume they secure the whole channel, but confidentiality requires TLS, not filtering.
- ✗
It prevents all types of attacks against the application
Why it's wrong here
A WAF applies signature and anomaly rules against known web attack patterns; it cannot block zero-days, business-logic abuse or attacks outside HTTP/S. It is tempting as a perimeter control, yet no single control prevents all attack types, so the absolute claim fails.
- ✓
It filters malicious HTTP requests and can block common web exploits
Why this is correct
A WAF inspects inbound HTTP traffic against rule sets such as the OWASP Core Rule Set, blocking SQL injection, cross-site scripting and similar exploits before they reach the application. This filtering at layer 7 satisfies the requirement to stop common web attacks rather than merely logging them.
- ✗
It performs static code analysis on the application
Why it's wrong here
A WAF inspects HTTP/S requests at layer 7, blocking injection and cross-site attacks in transit; it never reads application source code. It is tempting because WAF rule sets resemble code-level signatures, yet static analysis belongs to SAST tooling run during development, not inline traffic filtering.
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 CAS-005 exam frequently reuses these exact scenarios with slightly different constraints.
✓It filters malicious HTTP requests and can block common web exploitsCorrect answer▾
Why this is correct
A WAF inspects inbound HTTP traffic against rule sets such as the OWASP Core Rule Set, blocking SQL injection, cross-site scripting and similar exploits before they reach the application. This filtering at layer 7 satisfies the requirement to stop common web attacks rather than merely logging them.
✗It encrypts all traffic between client and serverWrong answer — click to see why▾
Why this is wrong here
Encryption is typically handled by TLS, not the WAF.
✗It prevents all types of attacks against the applicationWrong answer — click to see why▾
Why this is wrong here
WAFs cannot prevent all attacks, especially logic flaws or zero-days.
✗It performs static code analysis on the applicationWrong answer — click to see why▾
Why this is wrong here
Static code analysis is a separate process, not a WAF function.
Analysis generated from the official CAS-005blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CAS-005 practice question is part of Courseiva's free CompTIA 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 CAS-005 exam.