N10-009 Network Security Practice Question
A company wants to prevent unauthorized personal devices from connecting to the corporate wired network. Employees must authenticate using their domain credentials before gaining full network access. Which security measure should be implemented on the switch ports?
⚠ Common exam trap
It's easy for candidates to confuse port security with 802.1X, thinking that locking MAC addresses via sticky MAC provides user-based authentication, but it only controls device identity, not user credentials, and fails to meet the requirement for domain credential authentication.
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
802.1X is the correct choice because it provides port-based network access control (PNAC) that requires end devices to authenticate using domain credentials (e.g., via RADIUS) before being granted full network access. This ensures that only authorized users, not just authorized devices, can connect to the corporate wired network, meeting the requirement to prevent unauthorized personal devices.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
MAC filtering
Why it's wrong here
MAC filtering involves creating an access control list (ACL) that permits or denies network access based on a device's unique Media Access Control (MAC) address. While it can block specific known MAC addresses, it is inherently insecure for preventing unauthorized personal devices because MAC addresses are easily spoofed. An attacker can simply discover a legitimate MAC address and configure their unauthorized device to use it, thereby bypassing the filter without any authentication of the device or user.
When this WOULD be correct
A company wants to restrict network access to only approved devices based on their MAC addresses, without requiring user authentication. The question would specify that device identity, not user credentials, is the access control factor.
- ✓
802.1X
Why this is correct
802.1X provides robust port-based network access control, requiring authentication before a device gains full network access. It leverages the Extensible Authentication Protocol (EAP) to communicate with a central RADIUS server, which validates user or device credentials. Until successful authentication, the port remains in an unauthorized state, typically allowing only EAP traffic, effectively preventing unauthorized personal devices from connecting. This robust mechanism ensures only authenticated entities can access network resources.
- ✗
Port security with sticky MAC
Why it's wrong here
Port security with sticky MAC addresses limits the number of MAC addresses learned on a switch port and can dynamically save them to the configuration. While it prevents new, unknown MAC addresses from connecting once the limit is reached, it does not authenticate the *user* or *device identity* itself. An unauthorized personal device could still connect if it spoofs a legitimate MAC address or if the port's MAC limit hasn't been reached, making it ineffective against determined unauthorized access.
- ✗
VLAN hopping prevention
Why it's wrong here
VLAN hopping prevention techniques, such as disabling Dynamic Trunking Protocol (DTP) or ensuring native VLANs are not used for user traffic, are designed to secure the integrity of VLANs by preventing an attacker from gaining access to other VLANs. These measures focus on securing inter-VLAN communication paths and trunk links. However, they do not provide any mechanism to authenticate or authorize *end devices* attempting to connect to a specific access port, thus failing to address the core problem of preventing unauthorized personal devices from initially joining the network.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The N10-009 exam frequently reuses these exact scenarios with slightly different constraints.
✓802.1XCorrect answer▾
Why this is correct
802.1X provides robust port-based network access control, requiring authentication before a device gains full network access. It leverages the Extensible Authentication Protocol (EAP) to communicate with a central RADIUS server, which validates user or device credentials. Until successful authentication, the port remains in an unauthorized state, typically allowing only EAP traffic, effectively preventing unauthorized personal devices from connecting. This robust mechanism ensures only authenticated entities can access network resources.
✗MAC filteringWrong answer — click to see why▾
Why this is wrong here
MAC filtering only checks MAC addresses, not user credentials, so it cannot enforce domain authentication. It also does not prevent unauthorized devices if their MAC is spoofed or manually added.
★ When this WOULD be the correct answer
A company wants to restrict network access to only approved devices based on their MAC addresses, without requiring user authentication. The question would specify that device identity, not user credentials, is the access control factor.
Why candidates choose this
Candidates may confuse MAC filtering with port security or assume that controlling device identity is sufficient for authentication, overlooking the requirement for domain credential verification.
Analysis generated from the official N10-009blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
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
Network Device Hardening
Key term
Extensible Authentication Protocol
Extensible Authentication Protocol (EAP) is a flexible authentication framework used in network access control, particularly in wireless and point-to-point connections, that supports multiple authentication methods without requiring changes to the underlying protocol.
Key term
RADIUS
RADIUS is a network protocol that provides centralized authentication, authorization, and accounting management for users who connect and use a network service.
About these practice questions
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This N10-009 practice question is part of Courseiva's free CompTIA 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 N10-009 exam.