N10-009 Network Security Practice Question
A company wants to prevent unauthorized devices from connecting to the corporate network. The policy requires that only specific MAC addresses are permitted on switch ports. Which security feature should be implemented on the switches?
⚠ Common exam trap
The N10-009 exam often tests the distinction between MAC-based port security and 802.1X authentication, where candidates mistakenly choose 802.1X because it is a more robust access control method, but the question specifically asks for a feature that permits only specific MAC addresses, which is exactly what port security does.
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
✓
MAC filtering / Port security
MAC filtering, also known as port security, is the correct feature because it allows the switch to restrict access to a port based on the source MAC address of incoming frames. By configuring a list of allowed MAC addresses, the switch will drop traffic from any unauthorized device, directly enforcing the policy that only specific MAC addresses are permitted on switch ports.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
802.1X authentication
Why it's wrong here
802.1X authentication is a port-based network access control protocol that requires users or devices to authenticate using credentials like usernames/passwords or digital certificates before gaining network access. While it can be configured with MAC Authentication Bypass (MAB) as a fallback for non-802.1X capable devices, its primary function is identity-based authentication, not solely restricting access based on a static list of MAC addresses. Therefore, it doesn't directly address the specific need for simple MAC-based restriction.
- ✓
MAC filtering / Port security
Why this is correct
Port security, often referred to as MAC filtering at the port level, is a Layer 2 security feature implemented on network switches. It enables an administrator to configure a specific switch port to allow traffic only from a predefined list of MAC addresses, or to dynamically learn a limited number of MAC addresses. If an unauthorized device with a different MAC address attempts to connect to that port, the switch can be configured to take action, such as shutting down the port, restricting traffic, or sending an alert, effectively preventing unauthorized device access.
- ✗
VLAN hopping prevention
Why it's wrong here
VLAN hopping prevention techniques are designed to mitigate attacks where an attacker attempts to gain access to VLANs other than the one they are assigned to. This typically involves disabling Dynamic Trunking Protocol (DTP) or ensuring the native VLAN on trunk ports is an unused VLAN. These measures protect against lateral movement between VLANs, but they do not prevent an unauthorized device from initially connecting to a switch port within its assigned VLAN.
When this WOULD be correct
A question asks: 'Which security feature prevents an attacker from using double-tagging or switch spoofing to access a different VLAN?' In that context, VLAN hopping prevention (e.g., disabling DTP, setting native VLAN to unused) would be the correct answer.
- ✗
DHCP snooping
Why it's wrong here
DHCP snooping is a security feature that filters untrusted DHCP messages and builds a DHCP snooping binding table, mapping MAC addresses to IP addresses, lease times, and VLANs. Its primary purpose is to prevent rogue DHCP servers from issuing IP addresses and to mitigate DHCP starvation attacks. While it uses MAC addresses in its operation, it does not directly restrict which specific MAC addresses are allowed to connect to a switch port in the first place, making it unsuitable for preventing unauthorized device connections based on MAC.
When this WOULD be correct
A company wants to prevent rogue DHCP servers from assigning IP addresses on the network and ensure only authorized DHCP servers can provide IP configurations. In that scenario, DHCP snooping would be the correct answer.
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.
✓MAC filtering / Port securityCorrect answer▾
Why this is correct
Port security, often referred to as MAC filtering at the port level, is a Layer 2 security feature implemented on network switches. It enables an administrator to configure a specific switch port to allow traffic only from a predefined list of MAC addresses, or to dynamically learn a limited number of MAC addresses. If an unauthorized device with a different MAC address attempts to connect to that port, the switch can be configured to take action, such as shutting down the port, restricting traffic, or sending an alert, effectively preventing unauthorized device access.
✗VLAN hopping preventionWrong answer — click to see why▾
Why this is wrong here
VLAN hopping prevention is a security measure to prevent traffic from jumping between VLANs, not to control which devices connect based on MAC addresses. The question specifically requires restricting unauthorized devices by MAC address, which is not addressed by VLAN hopping prevention.
★ When this WOULD be the correct answer
A question asks: 'Which security feature prevents an attacker from using double-tagging or switch spoofing to access a different VLAN?' In that context, VLAN hopping prevention (e.g., disabling DTP, setting native VLAN to unused) would be the correct answer.
Why candidates choose this
Candidates may confuse VLAN hopping prevention with access control, thinking it restricts device connectivity, or they may not clearly distinguish between layer 2 attacks and MAC-based port security.
✗DHCP snoopingWrong answer — click to see why▾
Why this is wrong here
DHCP snooping is a security feature that filters untrusted DHCP messages and builds a DHCP snooping binding table, but it does not restrict which MAC addresses can connect to a switch port; it prevents rogue DHCP servers, not unauthorized devices.
★ When this WOULD be the correct answer
A company wants to prevent rogue DHCP servers from assigning IP addresses on the network and ensure only authorized DHCP servers can provide IP configurations. In that scenario, DHCP snooping would be the correct answer.
Why candidates choose this
Candidates may confuse DHCP snooping with MAC-based access control because both involve MAC addresses, but DHCP snooping focuses on DHCP message validation, not port-level device authorization.
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
Access Control Model Comparison
| Model | Acronym | Who Controls Access? | Best For |
|---|---|---|---|
| Discretionary Access Control | DAC | Resource owner | Small teams, file shares |
| Mandatory Access Control | MAC | System / security labels | Classified govt / military |
| Role-Based Access Control | RBAC | Administrator (via roles) | Enterprise environments |
| Attribute-Based Access Control | ABAC | Policy engine (user + resource attributes) | Fine-grained, dynamic policies |
| Rule-Based Access Control | RuBAC | System rules / ACLs | Firewall rules, network ACLs |
Go deeper
Related to this question
Learn chapter
Network Device Hardening
Key term
MAC address
A MAC address is a unique hardware identifier assigned to a network interface card that allows devices to communicate on a local network.
Key term
Security
Security in IT is the practice of protecting systems, networks, and data from unauthorized access, damage, or theft.
About these practice questions
Courseiva writes every N10-009 question from scratch — 464 in total, each with an explanation and a wrong-answer breakdown. None are copied from real exams or dumps. Learn why practice questions differ from exam dumps →
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.