- A
DHCP snooping
DHCP snooping filters DHCP traffic and allows only trusted DHCP servers, preventing rogue DHCP servers from assigning IP addresses.
- B
Dynamic ARP Inspection
Why wrong: Dynamic ARP Inspection protects against ARP spoofing attacks, not rogue DHCP servers.
- C
Port security
Why wrong: Port security limits the number of MAC addresses on a port but does not prevent rogue DHCP servers.
- D
BPDU guard
Why wrong: BPDU guard disables a port if it receives a BPDU, protecting against rogue switches but not rogue DHCP servers.
Question 229 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 administrator discovers that client workstations are receiving IP addresses from an unknown device, causing network connectivity issues. Which security feature should be configured on switches to prevent rogue DHCP servers from assigning IP addresses?
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
✓
DHCP snooping
DHCP snooping is the correct security feature because it acts as a firewall between untrusted hosts and trusted DHCP servers. By configuring ports as trusted (where legitimate DHCP servers are connected) and untrusted (client-facing ports), the switch drops all DHCP server messages (OFFER, ACK, NAK) received on untrusted ports, effectively blocking rogue DHCP servers from assigning IP addresses.
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.
- ✓
DHCP snooping
Why this is correct
DHCP snooping filters DHCP traffic and allows only trusted DHCP servers, preventing rogue DHCP servers from assigning IP addresses.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Dynamic ARP Inspection
Why it's wrong here
Dynamic ARP Inspection protects against ARP spoofing attacks, not rogue DHCP servers.
When this WOULD be correct
Dynamic ARP Inspection would be the correct answer in a scenario where a network administrator needs to prevent man-in-the-middle attacks caused by an attacker sending fake ARP replies to associate their MAC address with the IP address of a legitimate device (e.g., the default gateway).
- ✗
Port security
Why it's wrong here
Port security limits the number of MAC addresses on a port but does not prevent rogue DHCP servers.
When this WOULD be correct
Port security would be correct in a question about preventing unauthorized devices from connecting to the network by limiting the number of MAC addresses allowed on a port, e.g., 'A network administrator wants to prevent users from connecting personal switches to the network. Which feature should be enabled on switch ports?'
- ✗
BPDU guard
Why it's wrong here
BPDU guard disables a port if it receives a BPDU, protecting against rogue switches but not rogue DHCP servers.
When this WOULD be correct
A network administrator wants to prevent unauthorized switches from being connected to access ports and causing spanning tree loops. BPDU guard would be the correct feature to configure on switch ports to disable them if a BPDU is received.
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.
✓DHCP snoopingCorrect answer▾
Why this is correct
DHCP snooping filters DHCP traffic and allows only trusted DHCP servers, preventing rogue DHCP servers from assigning IP addresses.
✗Dynamic ARP InspectionWrong answer — click to see why▾
Why this is wrong here
Dynamic ARP Inspection (DAI) is used to prevent ARP spoofing attacks by validating ARP packets, not to block rogue DHCP servers. The question specifically asks about preventing unauthorized DHCP server activity, which is addressed by DHCP snooping.
★ When this WOULD be the correct answer
Dynamic ARP Inspection would be the correct answer in a scenario where a network administrator needs to prevent man-in-the-middle attacks caused by an attacker sending fake ARP replies to associate their MAC address with the IP address of a legitimate device (e.g., the default gateway).
Why candidates choose this
Candidates may confuse DAI with DHCP snooping because both are security features that rely on a trusted database (DHCP snooping binding table) and are often implemented together. They might think DAI can also filter DHCP traffic, but its role is limited to ARP validation.
✗Port securityWrong answer — click to see why▾
Why this is wrong here
Port security limits the number of MAC addresses per switch port but does not inspect DHCP messages or block unauthorized DHCP servers. It cannot prevent rogue DHCP servers from assigning IP addresses.
★ When this WOULD be the correct answer
Port security would be correct in a question about preventing unauthorized devices from connecting to the network by limiting the number of MAC addresses allowed on a port, e.g., 'A network administrator wants to prevent users from connecting personal switches to the network. Which feature should be enabled on switch ports?'
Why candidates choose this
Candidates may confuse port security with DHCP snooping because both are switch security features, and they might think that restricting MAC addresses can block rogue DHCP servers, not realizing that DHCP snooping specifically validates DHCP messages.
✗BPDU guardWrong answer — click to see why▾
Why this is wrong here
BPDU guard is used to prevent loops by disabling ports that receive Bridge Protocol Data Units (BPDUs) from unauthorized switches, not to block rogue DHCP servers.
★ When this WOULD be the correct answer
A network administrator wants to prevent unauthorized switches from being connected to access ports and causing spanning tree loops. BPDU guard would be the correct feature to configure on switch ports to disable them if a BPDU is received.
Why candidates choose this
Candidates may confuse BPDU guard with DHCP snooping because both are security features that protect against unauthorized network devices, but they address different threats.
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 confuse DHCP snooping with Dynamic ARP Inspection (DAI) because both rely on the DHCP snooping binding table, but DAI only validates ARP packets, not DHCP server messages.
Detailed technical explanation
How to think about this question
DHCP snooping builds a DHCP snooping binding table by monitoring DHCPACK messages from trusted servers, mapping client MAC, IP, VLAN, port, and lease time. This table is then used by Dynamic ARP Inspection (DAI) and IP Source Guard to enforce IP-to-MAC bindings. In a real-world scenario, a misconfigured home router plugged into an access port can act as a rogue DHCP server; DHCP snooping drops its OFFER messages, preventing IP address conflicts and connectivity loss.
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
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: DHCP snooping — DHCP snooping is the correct security feature because it acts as a firewall between untrusted hosts and trusted DHCP servers. By configuring ports as trusted (where legitimate DHCP servers are connected) and untrusted (client-facing ports), the switch drops all DHCP server messages (OFFER, ACK, NAK) received on untrusted ports, effectively blocking rogue DHCP servers from assigning IP addresses.
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
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