- A
BPDU guard
Why wrong: BPDU guard protects against STP manipulation, not against MAC flooding.
- B
Port security
Port security limits the number of MAC addresses per port, directly mitigating MAC flooding attacks.
- C
DHCP snooping
Why wrong: DHCP snooping prevents rogue DHCP servers but does not prevent MAC flooding.
- D
Dynamic ARP Inspection (DAI)
Why wrong: DAI verifies ARP packets against DHCP snooping bindings and prevents ARP spoofing, not MAC flooding.
Question 43 of 520
N10-009 Network Security Practice Question
This N10-009 practice question tests your understanding of network security. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 network security analyst notices that a switch's CPU utilization is spiking and that the switch is flooding unicast frames to all ports. The analyst suspects a MAC address table overflow attack. Which of the following security features should be configured on the switch's access ports to mitigate this type of attack?
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
✓
Port security
Port security mitigates MAC address table overflow attacks by limiting the number of MAC addresses that can be learned on an access port. When the configured limit is exceeded, the switch can take action (e.g., shutdown or restrict) to prevent an attacker from flooding the CAM table with fake source MAC addresses, which would otherwise cause the switch to fail open and flood unicast frames out all 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.
- ✗
BPDU guard
Why it's wrong here
BPDU guard protects against STP manipulation, not against MAC flooding.
When this WOULD be correct
BPDU guard is correct when the question asks how to prevent a rogue switch from being connected to an access port and causing a spanning tree topology change (e.g., 'A network administrator wants to ensure that no unauthorized switches are connected to access ports. Which feature should be enabled?').
- ✓
Port security
Why this is correct
Port security limits the number of MAC addresses per port, directly mitigating MAC flooding attacks.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
DHCP snooping
Why it's wrong here
DHCP snooping prevents rogue DHCP servers but does not prevent MAC flooding.
- ✗
Dynamic ARP Inspection (DAI)
Why it's wrong here
DAI verifies ARP packets against DHCP snooping bindings and prevents ARP spoofing, not MAC flooding.
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.
✓Port securityCorrect answer▾
Why this is correct
Port security limits the number of MAC addresses per port, directly mitigating MAC flooding attacks.
✗BPDU guardWrong answer — click to see why▾
Why this is wrong here
BPDU guard prevents bridge loops by disabling ports receiving BPDUs, but it does not protect against MAC address table overflow attacks, which are mitigated by limiting the number of MAC addresses learned per port via port security.
★ When this WOULD be the correct answer
BPDU guard is correct when the question asks how to prevent a rogue switch from being connected to an access port and causing a spanning tree topology change (e.g., 'A network administrator wants to ensure that no unauthorized switches are connected to access ports. Which feature should be enabled?').
Why candidates choose this
Candidates may confuse BPDU guard with port security because both are common switch security features, and the term 'guard' sounds like it could prevent attacks, leading them to incorrectly associate it with MAC flooding.
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 trap here is that candidates often confuse port security with other Layer 2 security features like BPDU guard or DHCP snooping, but only port security directly limits the number of MAC addresses learned on a port to prevent CAM table overflow.
Detailed technical explanation
How to think about this question
Under the hood, a MAC address table overflow attack exploits the switch's limited Content Addressable Memory (CAM) table size; once full, the switch enters a fail-open state where it floods all unknown unicast frames out every port, effectively turning it into a hub. Port security counters this by enforcing a per-port MAC address limit (e.g., 'switchport port-security maximum 1'), and when exceeded, the port can be err-disabled or drop traffic, preserving the CAM table integrity. In a real-world scenario, an attacker on an access port could use a tool like macof to generate thousands of random source MAC addresses, causing network-wide flooding and potential eavesdropping.
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 practitioner preparing for the N10-009 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
Visual reference
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: Port security — Port security mitigates MAC address table overflow attacks by limiting the number of MAC addresses that can be learned on an access port. When the configured limit is exceeded, the switch can take action (e.g., shutdown or restrict) to prevent an attacker from flooding the CAM table with fake source MAC addresses, which would otherwise cause the switch to fail open and flood unicast frames out all 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
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
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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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