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CAS-004 Practice Question: A security architect is designing a segmentation…
A security architect is designing a segmentation strategy for a multi-tier web application. The public-facing web servers must communicate only with application servers, and application servers must communicate only with database servers. The architect wants to use a firewall that can inspect application-layer traffic to prevent SQL injection attacks. Which firewall type should be deployed between the application tier and the database tier?
⚠ Common exam trap
A common mix-up: candidates confuse the WAF's ability to inspect HTTP traffic with the need for application-layer inspection between application and database tiers, forgetting that database protocols (e.g., SQL) are not HTTP-based and require a different inspection engine like an NGFW with IPS.
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
✓
Next-generation firewall (NGFW) with intrusion prevention
A next-generation firewall (NGFW) with intrusion prevention is the correct choice because it can perform deep packet inspection (DPI) at the application layer, allowing it to detect and block SQL injection payloads within database queries. Unlike simpler firewalls, an NGFW integrates signature-based and behavioral IPS engines that can identify malicious SQL patterns (e.g., 'OR 1=1') in traffic between the application and database tiers, providing the required application-layer inspection.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Packet filtering firewall
Why it's wrong here
Packet filtering only inspects headers, not application payloads, so it cannot detect SQL injection.
- ✓
Next-generation firewall (NGFW) with intrusion prevention
Why this is correct
NGFWs can perform deep packet inspection and use IPS signatures to detect SQL injection in database protocols.
- ✗
Stateful firewall
Why it's wrong here
Stateful firewalls track connection state but do not inspect application-layer content.
- ✗
Web application firewall (WAF)
Why it's wrong here
WAFs inspect HTTP traffic; database traffic uses protocols like MS-SQL or MySQL, not HTTP.
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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.