easyMultiple ChoiceObjective-mapped
CAS-004 Practice Question: A small business is designing a defense-in-depth…
A small business is designing a defense-in-depth strategy for its e-commerce website. The web server is hosted in a cloud provider and handles credit card transactions. Which of the following additional controls best complements the existing firewall and IDS?
⚠ Common exam trap
Many exam-takers confuse a SIEM or load balancer with a security control, but the question specifically asks for a control that 'complements' existing firewall and IDS by addressing the missing application-layer protection, which only a WAF provides.
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
✓
Implement a web application firewall (WAF)
A web application firewall (WAF) is the correct complement because it specifically protects against application-layer attacks (e.g., SQL injection, cross-site scripting) that a network firewall and IDS cannot block. Since the e-commerce site handles credit card transactions, a WAF is critical for PCI DSS compliance and to filter malicious HTTP/HTTPS traffic targeting the web application logic.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Set up a security information and event management (SIEM) system
Why it's wrong here
SIEM provides logging and analysis but is not a preventive control.
- ✗
Add a load balancer with SSL termination
Why it's wrong here
Load balancers improve availability and offload encryption, but do not provide security inspection.
- ✓
Implement a web application firewall (WAF)
Why this is correct
A WAF inspects HTTP/HTTPS traffic and blocks SQL injection, XSS, etc., adding a critical defense layer.
- ✗
Deploy a network-based antivirus on the web server
Why it's wrong here
Antivirus protects the server but does not address application-layer threats.
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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.