Quick Answer
The answer is implementing network access control (NAC). NAC is the correct choice because it actively evaluates each device’s posture—checking OS patch levels, antivirus status, and disk encryption—against a defined compliance policy before granting network access, and it can quarantine non-compliant devices to a remediation VLAN or deny access entirely. On the CISSP exam, this question tests your understanding of how NAC enforces dynamic, policy-based admission at the network layer, distinguishing it from static controls like encryption or authentication alone. A common trap is confusing NAC with endpoint protection or VPNs, but remember that NAC is the gatekeeper that checks device health before the handshake. Memory tip: think of NAC as the bouncer who checks your ID and vaccination card before letting you into the club—if you’re not compliant, you wait in the alley (remediation VLAN).
This CISSP practice question tests your understanding of security operations. 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.
An organization is implementing a bring-your-own-device (BYOD) policy. Which security control should be enforced to ensure that only compliant devices can access corporate resources?
Using a VPN concentrator
Why wrong: VPN concentrators don't validate device health.
Requiring strong passwords
Why wrong: Passwords don't verify device compliance.
Implementing network access control (NAC)
NAC checks device posture before network access.
Enabling full disk encryption
Why wrong: Encryption protects data but doesn't enforce compliance at access.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Implementing network access control (NAC)
Network access control (NAC) is the correct control because it evaluates device posture (e.g., OS patch level, antivirus status, disk encryption) against a compliance policy before granting network access. NAC can quarantine non-compliant devices to a remediation VLAN or deny access entirely, ensuring only trusted endpoints reach corporate resources. This is distinct from generic encryption or authentication controls, as NAC enforces a dynamic, policy-based admission decision at the network layer.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Using a VPN concentrator
Why it's wrong here
VPN concentrators don't validate device health.
Requiring strong passwords
Why it's wrong here
Passwords don't verify device compliance.
Implementing network access control (NAC)
Why this is correct
NAC checks device posture before network access.
Related concept
Read the scenario before looking for a memorised answer.
Enabling full disk encryption
Why it's wrong here
Encryption protects data but doesn't enforce compliance at access.
Common exam traps
The trap here is that candidates often confuse authentication controls (like strong passwords or VPN) with device compliance enforcement, but NAC is the only option that actively checks and enforces a security posture before granting network access.
Detailed technical explanation
NAC typically operates using 802.1X (port-based authentication) or DHCP/ARP inspection to enforce policies. When a device connects, the NAC appliance performs a posture assessment via agents or clientless probes (e.g., checking registry keys, file versions, or running services). If the device fails compliance, it is placed into a restricted VLAN with limited access (e.g., only to a remediation server), and re-evaluated after fixes are applied. In a BYOD scenario, NAC can also integrate with MDM/UEM solutions to enforce containerization or remote wipe policies.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A developer is choosing between AES-256 (symmetric) and RSA-2048 (asymmetric) for encrypting a large file that will be sent to a partner. Symmetric encryption is fast but requires key exchange; asymmetric is slower but solves the key distribution problem. A hybrid approach — encrypt the file with AES, encrypt the AES key with RSA — is standard. Questions like this test whether you understand when each approach applies.
What to study next
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FAQ
Security Operations — This question tests Security Operations — Read the scenario before looking for a memorised answer..
The correct answer is: Implementing network access control (NAC) — Network access control (NAC) is the correct control because it evaluates device posture (e.g., OS patch level, antivirus status, disk encryption) against a compliance policy before granting network access. NAC can quarantine non-compliant devices to a remediation VLAN or deny access entirely, ensuring only trusted endpoints reach corporate resources. This is distinct from generic encryption or authentication controls, as NAC enforces a dynamic, policy-based admission decision at the network layer.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 24, 2026
This CISSP practice question is part of Courseiva's free ISC2 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 CISSP exam.
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