Question 354 of 510

Security Architecture →mediumMultiple SelectObjective-mapped

CAS-004 Security Architecture Practice Question

This CAS-004 practice question tests your understanding of security architecture. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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 data center to reduce the attack surface. Which TWO of the following are best practices for implementing effective network segmentation?

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.

Question 1mediummulti select

Full question →

A
Deploy network access control (NAC) to authenticate devices before granting network access.
Why wrong: NAC addresses endpoint compliance, not segmentation itself.
B
Place all external-facing services in a single shared DMZ segment.
Why wrong: Consolidating external services in one DMZ increases risk; each service should have its own segment if possible.
C
Allow any-to-any communication within each security zone to avoid performance bottlenecks.
Why wrong: Any-to-any traffic within a zone undermines the purpose of segmentation.
D
Use VLANs to logically isolate traffic between different security zones.
VLANs provide Layer 2 isolation, which is a fundamental segmentation technique.
E
Implement microsegmentation using host-based firewalls or virtual networking to restrict east-west traffic.
Microsegmentation limits lateral movement by enforcing granular policies.

Full breakdown with real-world context →

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.

Option A (Use VLANs for isolation) is correct because VLANs provide logical separation at Layer 2. Option B (Implement microsegmentation with firewalls) is correct because microsegmentation uses granular firewall rules to isolate workloads. Option C is incorrect because a shared DMZ for all external services increases risk. Option D is incorrect because NAC focuses on device authentication, not segmentation. Option E is incorrect because any-to-any traffic defeats segmentation.

Key principle: A trunk being up does not mean the VLAN is allowed across it. Always verify the allowed VLAN list and whether the VLAN exists on both switches.

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.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Access ports place end devices into a single VLAN.
✓
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.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Access ports place end devices into a single VLAN.

Common exam traps

Common exam trap: an active trunk can still block the VLAN you need

A trunk being up does not prove every VLAN is crossing it. Check allowed VLAN lists, native VLAN mismatch, VLAN existence and access-port assignment.

Detailed technical explanation

How to think about this question

VLAN questions usually combine access-port and trunking clues. The key is to identify whether the issue is local to one switchport, caused by the trunk, or caused by the VLAN not existing where it needs to exist.

KKey Concepts to Remember

Access ports place end devices into a single VLAN.
Trunk ports carry multiple VLANs between switches.
Allowed VLAN lists decide which VLANs can cross a trunk.
Native VLAN mismatch can create confusing symptoms.

TExam Day Tips

Use show vlan brief to verify access VLANs.
Use show interfaces trunk to verify trunk state and allowed VLANs.
Do not treat every same-VLAN issue as a routing problem.

Key takeaway

A trunk being up does not mean the VLAN is allowed across it. Always verify the allowed VLAN list and whether the VLAN exists on both switches.

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.

Review VLAN allowed lists, native VLAN mismatch detection, and how to verify VLAN membership with show vlan brief and show interfaces trunk. Then practise related CAS-004 questions on switching, trunking, and access-port configuration.

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FAQ

Questions learners often ask

What does this CAS-004 question test?

Security Architecture — This question tests Security Architecture — Access ports place end devices into a single VLAN..

What is the correct answer to this question?

The correct answer is: Use VLANs to logically isolate traffic between different security zones. — Option A (Use VLANs for isolation) is correct because VLANs provide logical separation at Layer 2. Option B (Implement microsegmentation with firewalls) is correct because microsegmentation uses granular firewall rules to isolate workloads. Option C is incorrect because a shared DMZ for all external services increases risk. Option D is incorrect because NAC focuses on device authentication, not segmentation. Option E is incorrect because any-to-any traffic defeats segmentation.

What should I do if I get this CAS-004 question wrong?

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?

Access ports place end devices into a single VLAN.

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