hardMultiple Choice
CAS-004 Practice Question: Is designing a new network architecture for a…
A security engineer is designing a new network architecture for a government agency that requires compliance with NIST SP 800-53. The network must segregate data tiers and enforce least privilege. Which of the following designs BEST meets the requirements?
⚠ Common exam trap
Candidates may mistakenly believe that VLANs combined with ACLs provide sufficient isolation for data tiers. However, NIST SP 800-53 requires dynamic access control and continuous verification, which VLANs and ACLs cannot support because they rely on static network segmentation rather than identity-based enforcement at the workload level.
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
✓
Zero-trust architecture with micro-segmentation and continuous verification.
Zero-trust architecture with micro-segmentation and continuous verification directly enforces least privilege by requiring authentication and authorization for every connection, regardless of source location. Micro-segmentation isolates data tiers at the workload level, preventing lateral movement, which aligns with NIST SP 800-53 access control and system and communications protection requirements.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Perimeter-based security with a VPN for remote access.
Why it's wrong here
Perimeter defence with VPN concentrates trust at the boundary, so east-west traffic between data tiers is unfiltered, breaching NIST SP 800-53 segregation and least-privilege controls. It suits legacy flat networks needing remote-access termination, not tiered segmentation, which requires internal enforcement points such as microsegmentation or security groups.
- ✓
Zero-trust architecture with micro-segmentation and continuous verification.
Why this is correct
Micro-segmentation enforces least privilege by permitting only explicitly authorised flows between individual workloads, satisfying NIST SP 800-53 access control and separation-of-duties controls. Continuous verification re-evaluates every request against identity and device posture, so a compromised tier cannot pivot laterally into adjacent data tiers.
- ✗
DMZ architecture with a single firewall between the internet and internal network.
Why it's wrong here
A single firewall cannot enforce the tier-to-tier least-privilege controls NIST SP 800-53 requires, because it inspects only the internet boundary, leaving east-west traffic between data tiers unfiltered. A DMZ suits publishing public-facing services while shielding internal hosts; here, internal segmentation, not perimeter exposure, is the requirement.
- ✗
Flat network with VLANs for each data tier and ACLs controlling traffic.
Why it's wrong here
VLANs on a flat network segment traffic logically but share one routing and enforcement domain, so ACLs alone cannot deliver the tier isolation and least privilege NIST SP 800-53 demands. It is tempting because VLANs are a common segmentation tool, but they suit internal traffic separation, not strict multi-tier enforcement.
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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.