- A
802.1X authentication
Why wrong: 802.1X uses usernames/passwords or certificates for authentication, not MAC addresses. While it can be integrated with MAC authentication bypass, the question specifically asks for MAC-based restriction.
- B
MAC filtering / Port security
Port security (MAC filtering) allows an administrator to define a list of allowed MAC addresses on a switch port. Any device with a MAC not on the list is blocked from sending traffic.
- C
VLAN hopping prevention
Why wrong: VLAN hopping prevention techniques (e.g., disabling DTP, setting native VLAN to unused) protect against attacks that attempt to access other VLANs, not against unauthorized device connections.
- D
DHCP snooping
Why wrong: DHCP snooping prevents rogue DHCP servers and maintains a binding table of IP-MAC addresses. It does not directly restrict which MAC addresses can connect to a port.
N10-009 Network Security Practice Question
This N10-009 practice question tests your understanding of network security. 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.
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?
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.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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 uses usernames/passwords or certificates for authentication, not MAC addresses. While it can be integrated with MAC authentication bypass, the question specifically asks for MAC-based restriction.
- ✓
MAC filtering / Port security
Why this is correct
Port security (MAC filtering) allows an administrator to define a list of allowed MAC addresses on a switch port. Any device with a MAC not on the list is blocked from sending traffic.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
VLAN hopping prevention
Why it's wrong here
VLAN hopping prevention techniques (e.g., disabling DTP, setting native VLAN to unused) protect against attacks that attempt to access other VLANs, not against unauthorized device connections.
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 prevents rogue DHCP servers and maintains a binding table of IP-MAC addresses. It does not directly restrict which MAC addresses can connect to a port.
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 (MAC filtering) allows an administrator to define a list of allowed MAC addresses on a switch port. Any device with a MAC not on the list is blocked from sending traffic.
✗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?”
Common exam traps
Common exam trap: answer the scenario, not the keyword
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.
Detailed technical explanation
How to think about this question
Port security works by learning MAC addresses on a switch port and comparing them against a configured list of allowed addresses (sticky MAC addresses can be used to dynamically learn and lock addresses). If a violation occurs (e.g., an unknown MAC address attempts to send traffic), the switch can take actions such as shutting down the port (errdisable state), dropping the offending frames, or generating a syslog message. In a real-world scenario, an attacker could spoof a permitted MAC address to bypass port security, so it is often combined with 802.1X for stronger authentication.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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.
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 |
What to study next
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FAQ
Questions learners often ask
What does this N10-009 question test?
Network Security — This question tests Network Security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: 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.
What should I do if I get this N10-009 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
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Last reviewed: Jun 11, 2026
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.
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