hardMultiple ChoiceObjective-mapped
ISC2 CC Practice Question: Implementing a security control to prevent…
You are implementing a security control to prevent unauthorized devices from connecting to the corporate wired network. Which network access control method should be used?
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
✓
802.1X authentication
802.1X authentication (D) is the correct network access control method for preventing unauthorized devices from connecting to the corporate wired network because it requires devices to authenticate at the port level before gaining network access, providing strong security. VLAN segmentation (A) separates traffic but does not authenticate devices. MAC address filtering (B) can be easily bypassed by spoofing. Network Access Control (C) is a broader concept that may include 802.1X, but 802.1X is the specific technology that provides the authentication mechanism.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
VLAN segmentation
Why it's wrong here
VLAN segmentation separates traffic but does not authenticate devices, so it is not the correct method for preventing unauthorized connections.
- ✗
MAC address filtering
Why it's wrong here
MAC address filtering can be bypassed by spoofing, so it is not a secure access control method.
- ✗
Network Access Control (NAC) only
Why it's wrong here
Network Access Control (NAC) is a broader concept, but 802.1X is the specific authentication technology that provides port-level security.
- ✓
802.1X authentication
Why this is correct
802.1X authentication requires devices to authenticate before gaining network access, providing port-level security that prevents unauthorized connections.
Visual reference
Quick reference
AAA Protocol Comparison
| Protocol | Port(s) | Encryption | Transport | Primary Use |
|---|---|---|---|---|
| RADIUS | 1812 / 1813 | Password only | UDP | Network access control |
| TACACS+ | 49 | Full packet | TCP | Device administration |
| Diameter | 3868 | Full session | TCP / SCTP | Carrier / mobile networks |
| 802.1X | — | EAP-based | Layer 2 | Port-based access control |
TACACS+ encrypts the entire packet; RADIUS only encrypts the password field — a key exam distinction.
Go deeper
Related to this question
Learn chapter
Introduction to Security Principles
Key term
VLAN
A VLAN (Virtual Local Area Network) is a logical grouping of network devices that behave as if they are on the same physical network segment, regardless of their actual physical location.
Key term
Access control
Access control is the security practice of determining who or what is allowed to view, use, or enter a resource, and under what conditions.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CC 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 CC exam.