- A
Use a single VLAN with access control lists to restrict traffic between servers.
Why wrong: ACLs alone cannot replace proper network segmentation and may be complex to manage.
- B
Place all servers in the same subnet and use host-based firewalls for isolation.
Why wrong: A flat network does not provide network-level segmentation, increasing risk.
- C
Deploy web servers in a DMZ, application servers in an internal network, and database servers in a separate restricted network with firewall rules allowing only necessary traffic.
This provides defense in depth with proper segmentation and access controls.
- D
Use a VPN concentrator for all external access and place all servers in a private subnet.
Why wrong: VPN-only access would hinder performance and does not address internal segmentation.
Quick Answer
The correct answer is to deploy web servers in a DMZ, application servers in an internal network, and database servers in a separate restricted network with firewall rules allowing only necessary traffic. This classic three-tier DMZ architecture for multi-tier web application security enforces the principle of least privilege by segmenting each tier into its own security zone, where the DMZ absorbs direct internet traffic while the internal and backend networks remain isolated behind stateful firewall rules that permit only specific, required flows. On the CompTIA SecurityX CAS-004 exam, this scenario tests your understanding of layered network segmentation and how to prevent lateral movement—a common trap is placing the database in the same internal network as the application server, which would expose sensitive data if the app tier is compromised. Remember the memory tip: “Web in the DMZ, App in the middle, DB in the back—never let the internet touch the stack.”
CAS-004 Security Architecture Practice Question
This CAS-004 practice question tests your understanding of security architecture. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 security architect is designing a network segmentation strategy for a multi-tier web application. The web servers must be accessible from the internet, while the application and database servers must only be accessible from the web tier. Which architecture best meets these requirements?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"best"Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
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
Deploy web servers in a DMZ, application servers in an internal network, and database servers in a separate restricted network with firewall rules allowing only necessary traffic.
Option C is correct because it implements a classic three-tier DMZ architecture: web servers in a DMZ (publicly accessible), application servers in an internal network (accessible only from the DMZ), and database servers in a restricted backend network (accessible only from the application tier). This layered segmentation enforces the principle of least privilege and uses firewall rules to control traffic between each tier, ensuring that internet-facing components cannot directly reach sensitive data stores.
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.
- ✗
Use a single VLAN with access control lists to restrict traffic between servers.
Why it's wrong here
ACLs alone cannot replace proper network segmentation and may be complex to manage.
- ✗
Place all servers in the same subnet and use host-based firewalls for isolation.
Why it's wrong here
A flat network does not provide network-level segmentation, increasing risk.
- ✓
Deploy web servers in a DMZ, application servers in an internal network, and database servers in a separate restricted network with firewall rules allowing only necessary traffic.
Why this is correct
This provides defense in depth with proper segmentation and access controls.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Use a VPN concentrator for all external access and place all servers in a private subnet.
Why it's wrong here
VPN-only access would hinder performance and does not address internal segmentation.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse network segmentation with simple access control lists or host-based firewalls, failing to recognize that true segmentation requires separate network zones (DMZ, internal, restricted) with firewall-enforced traffic flows between them.
Detailed technical explanation
How to think about this question
In a multi-tier DMZ architecture, the web tier typically resides in a perimeter network (DMZ) with stateful firewall rules allowing inbound HTTP/HTTPS (ports 80/443) from the internet, while outbound connections to the application tier are restricted to specific ports (e.g., 8080). The application tier then initiates connections to the database tier using protocols like TCP/1433 (MSSQL) or TCP/3306 (MySQL), often with source IP restrictions and application-layer firewalls. This design prevents direct database exposure and limits blast radius in case of a web server compromise.
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 help-desk technician troubleshoots why a newly connected PC cannot reach shared printers on the same floor. The cable is good, the switch port is active, but the PC is in VLAN 20 and the printers are in VLAN 10. The uplink trunk only allows VLAN 10. A trunk being up does not mean every VLAN crosses it.
What to study next
Got this wrong? Here's your next step.
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FAQ
Questions learners often ask
What does this CAS-004 question test?
Security Architecture — This question tests Security Architecture — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Deploy web servers in a DMZ, application servers in an internal network, and database servers in a separate restricted network with firewall rules allowing only necessary traffic. — Option C is correct because it implements a classic three-tier DMZ architecture: web servers in a DMZ (publicly accessible), application servers in an internal network (accessible only from the DMZ), and database servers in a restricted backend network (accessible only from the application tier). This layered segmentation enforces the principle of least privilege and uses firewall rules to control traffic between each tier, ensuring that internet-facing components cannot directly reach sensitive data stores.
What should I do if I get this CAS-004 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Same concept, more angles
1 more ways this is tested on CAS-004
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A security architect is designing a new DMZ for an e-commerce platform. The DMZ must host a web server, an API gateway, and a database server. The architect needs to minimize the attack surface while ensuring the web server can communicate with the API gateway, and the API gateway can communicate with the database. Which network segmentation approach best meets these requirements?
medium- A.Place all three services in the same DMZ subnet and use host-based firewalls to restrict traffic.
- B.Create two DMZ subnets: one for the web server and API gateway, and another for the database server.
- C.Place the web server in a DMZ subnet, the API gateway in a separate DMZ subnet, and the database server on the internal network.
- ✓ D.Create three separate DMZ subnets: one for the web server, one for the API gateway, and one for the database server, with firewall rules allowing only required traffic.
Why D: Option D is correct because it implements the principle of least privilege through network segmentation. By placing each service in its own DMZ subnet with firewall rules that allow only the required traffic (e.g., HTTP/HTTPS from web to API, SQL from API to database), the attack surface is minimized. This prevents lateral movement if one service is compromised, as an attacker cannot directly reach the database from the web server or the API gateway from the internet.
Last reviewed: Jun 11, 2026
This CAS-004 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-004 exam.
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