- A
Port security
Why wrong: Port security restricts the number of MAC addresses per port but does not inspect ARP packets.
- B
DHCP snooping
Why wrong: DHCP snooping filters rogue DHCP servers and builds a binding table, but does not directly validate ARP traffic.
- C
Dynamic ARP Inspection
DAI uses the DHCP snooping binding table to validate ARP packets and block spoofed ARP messages.
- D
MAC address filtering
Why wrong: MAC filtering controls which MAC addresses are allowed, but does not prevent ARP spoofing.
Question 230 of 520
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 security analyst receives an alert that an internal user's workstation is sending a high volume of ARP requests for multiple IP addresses on the local subnet. The analyst suspects a man-in-the-middle attack. Which security mechanism is most effective at mitigating this type of attack on a switched network?
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
✓
Dynamic ARP Inspection
Dynamic ARP Inspection (DAI) is the correct answer because it validates ARP packets on a switched network, ensuring that only legitimate ARP replies are forwarded. In a man-in-the-middle attack, an attacker sends spoofed ARP replies to associate their MAC address with the IP address of a legitimate host. DAI intercepts all ARP packets and compares them against a trusted binding table (built by DHCP snooping), dropping any that are invalid, thus preventing ARP spoofing.
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.
- ✗
Port security
Why it's wrong here
Port security restricts the number of MAC addresses per port but does not inspect ARP packets.
When this WOULD be correct
Port security would be correct in a question about preventing unauthorized devices from connecting to a switch port by limiting MAC addresses, such as 'Which feature restricts the number of MAC addresses learned on a port to prevent MAC flooding?'
- ✗
DHCP snooping
Why it's wrong here
DHCP snooping filters rogue DHCP servers and builds a binding table, but does not directly validate ARP traffic.
When this WOULD be correct
DHCP snooping would be the correct answer if the question described a scenario where a rogue DHCP server is assigning malicious IP configurations to clients, enabling man-in-the-middle attacks via DHCP spoofing.
- ✓
Dynamic ARP Inspection
Why this is correct
DAI uses the DHCP snooping binding table to validate ARP packets and block spoofed ARP messages.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
MAC address filtering
Why it's wrong here
MAC filtering controls which MAC addresses are allowed, but does not prevent ARP spoofing.
When this WOULD be correct
MAC address filtering would be correct in a scenario where the question asks for a mechanism to prevent unauthorized devices from connecting to the network by limiting access based on MAC addresses, such as in a small office with a static device list.
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.
✓Dynamic ARP InspectionCorrect answer▾
Why this is correct
DAI uses the DHCP snooping binding table to validate ARP packets and block spoofed ARP messages.
✗Port securityWrong answer — click to see why▾
Why this is wrong here
Port security limits the number of MAC addresses per port but does not inspect ARP packets, so it cannot prevent ARP spoofing or man-in-the-middle attacks.
★ When this WOULD be the correct answer
Port security would be correct in a question about preventing unauthorized devices from connecting to a switch port by limiting MAC addresses, such as 'Which feature restricts the number of MAC addresses learned on a port to prevent MAC flooding?'
Why candidates choose this
Candidates may think port security prevents all MAC-based attacks, confusing MAC address limiting with ARP inspection.
✗DHCP snoopingWrong answer — click to see why▾
Why this is wrong here
DHCP snooping filters DHCP messages to prevent rogue DHCP servers, but it does not inspect ARP traffic. The attack described involves ARP spoofing, which Dynamic ARP Inspection (DAI) directly mitigates by validating ARP packets against the DHCP snooping binding table.
★ When this WOULD be the correct answer
DHCP snooping would be the correct answer if the question described a scenario where a rogue DHCP server is assigning malicious IP configurations to clients, enabling man-in-the-middle attacks via DHCP spoofing.
Why candidates choose this
Candidates may confuse DHCP snooping with ARP inspection because both rely on the same binding table and are often implemented together, leading to the mistaken belief that DHCP snooping alone can prevent ARP-based attacks.
✗MAC address filteringWrong answer — click to see why▾
Why this is wrong here
MAC address filtering restricts which MAC addresses can communicate on a port, but it does not prevent ARP spoofing or man-in-the-middle attacks because an attacker can spoof a legitimate MAC address.
★ When this WOULD be the correct answer
MAC address filtering would be correct in a scenario where the question asks for a mechanism to prevent unauthorized devices from connecting to the network by limiting access based on MAC addresses, such as in a small office with a static device list.
Why candidates choose this
Candidates may confuse MAC address filtering with a security measure against ARP attacks, as both involve MAC addresses, but filtering does not validate ARP packets or prevent spoofing.
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 DHCP snooping and DAI, where candidates mistakenly choose DHCP snooping because it builds the binding table, but DAI is the actual mechanism that validates ARP packets to prevent man-in-the-middle attacks.
Detailed technical explanation
How to think about this question
DAI operates by intercepting all ARP requests and replies on untrusted ports and verifying each packet's sender MAC and sender IP against the DHCP snooping binding table. If no entry exists or the information mismatches, the packet is dropped. In a real-world scenario, an attacker could use a tool like arpspoof to send gratuitous ARP replies; DAI would drop these because the attacker's MAC is not bound to the target IP in the binding table. DAI also supports rate limiting to prevent ARP flooding attacks.
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 network engineer segments a warehouse floor into three subnets: 20 scanners, 5 printers, and 2 management hosts. Picking the wrong mask wastes addresses or leaves too few usable hosts. Exam questions test whether you can apply CIDR notation, calculate block size, and identify the correct usable-host range for a given prefix.
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: Dynamic ARP Inspection — Dynamic ARP Inspection (DAI) is the correct answer because it validates ARP packets on a switched network, ensuring that only legitimate ARP replies are forwarded. In a man-in-the-middle attack, an attacker sends spoofed ARP replies to associate their MAC address with the IP address of a legitimate host. DAI intercepts all ARP packets and compares them against a trusted binding table (built by DHCP snooping), dropping any that are invalid, thus preventing ARP spoofing.
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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