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CAS-004 Practice Question: A security architect is designing a network…
A security architect is designing a network segmentation strategy for a data center to reduce the attack surface. Which TWO of the following are best practices for implementing effective network segmentation?
⚠ Common exam trap
A common misconception is that NAC alone is a segmentation technique, when in fact it is an authentication and authorization mechanism that complements but does not replace Layer 2/3 isolation methods like VLANs or microsegmentation.
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
✓
Use VLANs to logically isolate traffic between different security zones.
VLANs (IEEE 802.1Q) provide Layer 2 isolation between security zones by segmenting broadcast domains, preventing traffic from crossing zone boundaries without a Layer 3 device (router/firewall). This reduces the attack surface by containing lateral movement within a single VLAN and enforcing access control at the gateway.
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 network access control (NAC) to authenticate devices before granting network access.
Why it's wrong here
NAC addresses endpoint compliance, not segmentation itself.
- ✗
Place all external-facing services in a single shared DMZ segment.
Why it's wrong here
Consolidating external services in one DMZ increases risk; each service should have its own segment if possible.
- ✗
Allow any-to-any communication within each security zone to avoid performance bottlenecks.
Why it's wrong here
Any-to-any traffic within a zone undermines the purpose of segmentation.
- ✓
Use VLANs to logically isolate traffic between different security zones.
Why this is correct
VLANs provide Layer 2 isolation, which is a fundamental segmentation technique.
- ✓
Implement microsegmentation using host-based firewalls or virtual networking to restrict east-west traffic.
Why this is correct
Microsegmentation limits lateral movement by enforcing granular policies.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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