Question 359 of 510

Security Engineering →mediumMultiple ChoiceObjective-mapped

Quick Answer

The answer is to authenticate and authorize every device and user for every resource access, and encrypt all communication. This is the core principle of zero trust network architecture because it eliminates implicit trust based on network location, requiring continuous verification for every request regardless of whether it originates from inside or outside the traditional perimeter. On the CompTIA SecurityX CAS-004 exam, this concept tests your understanding that zero trust replaces perimeter-based security with micro-segmentation and least-privilege access, making technologies like VPNs or VLANs insufficient as primary controls. A common trap is assuming that network segmentation alone satisfies zero trust, but the key is that every access attempt must be explicitly authenticated and authorized, with all communication encrypted end-to-end. Remember the mnemonic: AAA-E—Always Authenticate and Authorize, then Encrypt.

CAS-004 Security Engineering Practice Question

This CAS-004 practice question tests your understanding of security engineering. 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 zero-trust network architecture. Which of the following is a fundamental principle of zero trust?

Question 1mediummultiple choice

Full question →

A
Place all resources on the internal network and rely on perimeter firewalls.
Why wrong: Zero trust eliminates the concept of a trusted internal network; perimeter firewalls are not sufficient.
B
Authenticate and authorize every device and user for every resource access, and encrypt all communication.
This is the core of zero trust: never trust, always verify, and ensure encrypted communication.
C
Implement VLANs to separate traffic based on user roles.
Why wrong: VLANs are a form of network segmentation but do not enforce per-access authentication and encryption, which are key to zero trust.
D
Use a VPN to secure all remote access to the corporate network.
Why wrong: VPNs provide tunnel encryption but still grant network-level access; zero trust requires per-application access.

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

✓

Authenticate and authorize every device and user for every resource access, and encrypt all communication.

Option B is correct because zero trust requires all resources to be accessed securely regardless of location, and all communication should be encrypted. Option A is wrong because zero trust does not rely on network perimeter; it assumes no implicit trust. Option C is wrong because VPNs are a perimeter technology; zero trust uses micro-segmentation. Option D is wrong because VLANs are not a primary zero-trust control; they are network 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.

✗
Place all resources on the internal network and rely on perimeter firewalls.
Why it's wrong here
Zero trust eliminates the concept of a trusted internal network; perimeter firewalls are not sufficient.
✓
Authenticate and authorize every device and user for every resource access, and encrypt all communication.
Why this is correct
This is the core of zero trust: never trust, always verify, and ensure encrypted communication.
Related concept
Access ports place end devices into a single VLAN.
✗
Implement VLANs to separate traffic based on user roles.
Why it's wrong here
VLANs are a form of network segmentation but do not enforce per-access authentication and encryption, which are key to zero trust.
✗
Use a VPN to secure all remote access to the corporate network.
Why it's wrong here
VPNs provide tunnel encryption but still grant network-level access; zero trust requires per-application access.

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

What is the correct answer to this question?

The correct answer is: Authenticate and authorize every device and user for every resource access, and encrypt all communication. — Option B is correct because zero trust requires all resources to be accessed securely regardless of location, and all communication should be encrypted. Option A is wrong because zero trust does not rely on network perimeter; it assumes no implicit trust. Option C is wrong because VPNs are a perimeter technology; zero trust uses micro-segmentation. Option D is wrong because VLANs are not a primary zero-trust control; they are network segmentation.

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

What is the key concept behind this question?

Access ports place end devices into a single VLAN.

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