- A
Deploy an SD-WAN with dynamic path selection and encryption for all inter-site traffic.
Why wrong: SD-WAN optimizes routing but does not provide granular per-component access control.
- B
Implement micro-segmentation with stateful firewalls and explicit allow rules between each workload.
Micro-segmentation with explicit allow rules ensures only necessary traffic is permitted, adhering to least privilege.
- C
Use network ACLs on the cloud VPC and on-premises routers to deny all traffic by default, then allow required ports.
Why wrong: Network ACLs are stateless and less granular than stateful firewalls; they do not track connection state.
- D
Deploy a site-to-site VPN and route all inter-component traffic through a VPN concentrator.
Why wrong: VPN concentrators create a trust boundary but do not enforce least privilege at the component level.
CAS-004 Security Architecture Practice Question
This CAS-004 practice question tests your understanding of security architecture. 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 security architect is designing a zero-trust network architecture for a hybrid cloud environment. The company uses on-premises servers and AWS. Which of the following best implements the principle of least privilege for inter-component communication?
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.
Clue:
"least"Why it matters: You want the option with minimum overhead, fewest steps, or lowest impact — not the most feature-rich or comprehensive answer.
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 micro-segmentation with stateful firewalls and explicit allow rules between each workload.
Option B is correct because micro-segmentation with stateful firewalls and explicit allow rules enforces least privilege at the workload level, ensuring that only explicitly permitted inter-component traffic is allowed. This approach is fundamental to zero-trust architectures, as it reduces the attack surface by preventing lateral movement, even within the same subnet or VPC.
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.
- ✗
Deploy an SD-WAN with dynamic path selection and encryption for all inter-site traffic.
Why it's wrong here
SD-WAN optimizes routing but does not provide granular per-component access control.
- ✓
Implement micro-segmentation with stateful firewalls and explicit allow rules between each workload.
Why this is correct
Micro-segmentation with explicit allow rules ensures only necessary traffic is permitted, adhering to least privilege.
Clue confirmation
The clue words "best", "least" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Use network ACLs on the cloud VPC and on-premises routers to deny all traffic by default, then allow required ports.
Why it's wrong here
Network ACLs are stateless and less granular than stateful firewalls; they do not track connection state.
- ✗
Deploy a site-to-site VPN and route all inter-component traffic through a VPN concentrator.
Why it's wrong here
VPN concentrators create a trust boundary but do not enforce least privilege at the component level.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the misconception that network-layer controls like ACLs or VPNs are sufficient for zero-trust least privilege, when in fact they lack the workload-level granularity and stateful enforcement required for true micro-segmentation.
Detailed technical explanation
How to think about this question
Micro-segmentation leverages distributed stateful firewalls (e.g., AWS Security Groups or NSX Distributed Firewall) that track connection state and enforce allow rules at the virtual NIC level, enabling per-workload policies regardless of IP address changes. In a hybrid cloud, this can be implemented using policy-based segmentation that spans on-premises and cloud workloads via consistent rule sets, preventing lateral movement even if an attacker compromises one component. A real-world scenario is a multi-tier application where the web tier can only talk to the app tier on specific ports, and the app tier can only talk to the database tier, with all other traffic implicitly denied.
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 small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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Security Architecture — study guide chapter
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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: Implement micro-segmentation with stateful firewalls and explicit allow rules between each workload. — Option B is correct because micro-segmentation with stateful firewalls and explicit allow rules enforces least privilege at the workload level, ensuring that only explicitly permitted inter-component traffic is allowed. This approach is fundamental to zero-trust architectures, as it reduces the attack surface by preventing lateral movement, even within the same subnet or VPC.
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", "least". 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
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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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