- A
Port security
Why wrong: Port security limits the number of MAC addresses on a port, but does not validate ARP messages.
- B
DHCP snooping
Why wrong: DHCP snooping filters DHCP messages and builds a binding table, but does not inspect ARP packets directly. However, DAI relies on DHCP snooping.
- C
Dynamic ARP Inspection
DAI uses the DHCP snooping binding table to validate ARP packets and drop invalid ones, preventing ARP spoofing.
- D
VLAN segmentation
Why wrong: VLAN segmentation limits broadcast domains but does not prevent ARP spoofing within the same VLAN.
Question 460 of 520
N10-009 Network Security Practice Question
This N10-009 practice question tests your understanding of network security. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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.
Which security feature on a switch can prevent an attacker from sending forged ARP messages to redirect traffic?
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 against a trusted database (the DHCP snooping binding table) to ensure that the MAC-to-IP address mapping is legitimate. By intercepting and verifying all ARP requests and replies on untrusted ports, DAI prevents an attacker from sending forged ARP messages to redirect traffic (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 limits the number of MAC addresses on a port, but does not validate ARP messages.
When this WOULD be correct
Port security would be correct for a question like: 'Which feature prevents MAC flooding attacks by limiting the number of MAC addresses learned on a switch port?'
- ✗
DHCP snooping
Why it's wrong here
DHCP snooping filters DHCP messages and builds a binding table, but does not inspect ARP packets directly. However, DAI relies on DHCP snooping.
When this WOULD be correct
A question asks: 'Which feature prevents rogue DHCP servers from assigning false IP addresses?' DHCP snooping would be the correct answer because it filters DHCP server messages on untrusted ports.
- ✓
Dynamic ARP Inspection
Why this is correct
DAI uses the DHCP snooping binding table to validate ARP packets and drop invalid ones, preventing ARP spoofing.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
VLAN segmentation
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 drop invalid ones, preventing ARP spoofing.
✗Port securityWrong answer — click to see why▾
Why this is wrong here
Port security limits MAC addresses on a port but does not inspect or validate ARP packets, so it cannot prevent forged ARP messages used in ARP spoofing attacks.
★ When this WOULD be the correct answer
Port security would be correct for a question like: 'Which feature prevents MAC flooding attacks by limiting the number of MAC addresses learned on a switch port?'
Why candidates choose this
Candidates may confuse port security with ARP inspection because both involve MAC addresses, but port security does not validate ARP packet contents.
✗DHCP snoopingWrong answer — click to see why▾
Why this is wrong here
DHCP snooping validates DHCP messages and builds a binding database, but it does not inspect or filter ARP messages. It cannot prevent forged ARP attacks directly.
★ When this WOULD be the correct answer
A question asks: 'Which feature prevents rogue DHCP servers from assigning false IP addresses?' DHCP snooping would be the correct answer because it filters DHCP server messages on untrusted ports.
Why candidates choose this
Candidates may confuse DHCP snooping with Dynamic ARP Inspection (DAI) because DAI often relies on the DHCP snooping binding table. They might think DHCP snooping alone can stop ARP spoofing.
✗VLAN segmentationWrong answer — click to see why▾
Why this is wrong here
VLAN segmentation isolates network traffic into separate broadcast domains but does not inspect or validate ARP messages, so it cannot prevent forged ARP attacks that redirect traffic within the same VLAN.
★ When this WOULD be the correct answer
A question asking 'Which feature can be used to isolate broadcast domains and limit the scope of ARP spoofing attacks?' would make VLAN segmentation correct, as it reduces the attack surface by separating traffic.
Why candidates choose this
Candidates may think VLAN segmentation prevents ARP spoofing because it logically separates traffic, but it lacks the packet inspection needed to detect and block forged ARP replies.
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 (which builds the trust database) and Dynamic ARP Inspection (which uses that database to validate ARP traffic), leading candidates to mistakenly choose DHCP snooping as the direct defense against ARP spoofing.
Detailed technical explanation
How to think about this question
DAI operates by comparing the sender MAC and sender IP in each ARP packet against entries in the DHCP snooping binding table; if no match is found, the packet is dropped. It also enforces rate limiting on ARP packets to prevent ARP flooding attacks. In a real-world scenario, an attacker on an untrusted port could send a gratuitous ARP claiming the gateway's IP, but DAI would drop it because the MAC address does not match the binding table entry.
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.
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
Got this wrong? Here's your next step.
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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 against a trusted database (the DHCP snooping binding table) to ensure that the MAC-to-IP address mapping is legitimate. By intercepting and verifying all ARP requests and replies on untrusted ports, DAI prevents an attacker from sending forged ARP messages to redirect traffic (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.
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Last reviewed: Jun 11, 2026
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