- A
802.1X with RADIUS authentication and guest VLAN
Why wrong: 802.1X can place unauthorized devices in a guest VLAN but does not disable the port or automatically re-enable it based on a simple time period.
- B
Port security with violation mode 'shutdown' and errdisable recovery interval
Port security shutdown disables the port on violation, and errdisable recovery allows automatic re-enablement after a configured time.
- C
DHCP snooping and dynamic ARP inspection
Why wrong: These features prevent DHCP spoofing and ARP poisoning but do not disable ports on unauthorized connection or auto-recover.
- D
Storm control and broadcast suppression
Why wrong: These control traffic storms, not unauthorized device access.
Question 378 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 security auditor discovers that several unused switch ports are in default configuration. The auditor recommends implementing a security measure that will disable the port if an unauthorized device is connected, and then automatically re-enable the port after a specified time period. Which feature should be configured on the switch ports?
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 with violation mode 'shutdown' and errdisable recovery interval
Port security with violation mode 'shutdown' disables the port when an unauthorized device is detected, and the errdisable recovery interval automatically re-enables the port after a specified time period. This directly matches the auditor's requirement to disable on unauthorized connection and auto-re-enable after a timeout.
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 with RADIUS authentication and guest VLAN
Why it's wrong here
802.1X can place unauthorized devices in a guest VLAN but does not disable the port or automatically re-enable it based on a simple time period.
When this WOULD be correct
This option would be correct in a scenario requiring network access control where unauthorized devices should be placed in a restricted VLAN (guest VLAN) rather than having the port disabled. For example: 'A company wants to allow guests internet-only access while blocking internal resources, using RADIUS authentication.'
- ✓
Port security with violation mode 'shutdown' and errdisable recovery interval
Why this is correct
Port security shutdown disables the port on violation, and errdisable recovery allows automatic re-enablement after a configured time.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
DHCP snooping and dynamic ARP inspection
Why it's wrong here
These features prevent DHCP spoofing and ARP poisoning but do not disable ports on unauthorized connection or auto-recover.
When this WOULD be correct
A question asking for a feature that prevents DHCP starvation attacks and ARP spoofing by filtering DHCP messages and validating ARP packets on untrusted ports would make DHCP snooping and DAI the correct answer.
- ✗
Storm control and broadcast suppression
Why it's wrong here
These control traffic storms, not unauthorized device access.
When this WOULD be correct
A question asking: 'Which feature should be configured to prevent a broadcast storm from overwhelming a switch port?' would make storm control the correct answer, as it limits the rate of incoming broadcast traffic.
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 security with violation mode 'shutdown' and errdisable recovery intervalCorrect answer▾
Why this is correct
Port security shutdown disables the port on violation, and errdisable recovery allows automatic re-enablement after a configured time.
✗802.1X with RADIUS authentication and guest VLANWrong answer — click to see why▾
Why this is wrong here
802.1X with RADIUS authentication and guest VLAN does not automatically disable a port upon unauthorized connection; it grants limited access via guest VLAN. It also does not automatically re-enable the port after a timeout, as errdisable recovery is specific to port security violation modes.
★ When this WOULD be the correct answer
This option would be correct in a scenario requiring network access control where unauthorized devices should be placed in a restricted VLAN (guest VLAN) rather than having the port disabled. For example: 'A company wants to allow guests internet-only access while blocking internal resources, using RADIUS authentication.'
Why candidates choose this
Candidates may confuse 802.1X with port security because both deal with unauthorized device access, and the guest VLAN concept seems similar to disabling the port. They overlook that 802.1X does not physically disable the port or provide automatic re-enablement.
✗DHCP snooping and dynamic ARP inspectionWrong answer — click to see why▾
Why this is wrong here
DHCP snooping and dynamic ARP inspection are security features that prevent DHCP spoofing and ARP poisoning attacks, but they do not disable ports upon unauthorized device connection or automatically re-enable them after a timeout.
★ When this WOULD be the correct answer
A question asking for a feature that prevents DHCP starvation attacks and ARP spoofing by filtering DHCP messages and validating ARP packets on untrusted ports would make DHCP snooping and DAI the correct answer.
Why candidates choose this
Candidates may confuse the port disabling behavior with the concept of 'shutdown' in DHCP snooping (which shuts down ports with DHCP attacks) or mistakenly think DAI can disable ports, but neither provides the automatic re-enablement described.
✗Storm control and broadcast suppressionWrong answer — click to see why▾
Why this is wrong here
Storm control and broadcast suppression are used to limit excessive broadcast, multicast, or unicast traffic to prevent network storms, not to disable ports upon unauthorized device connection or to automatically re-enable them after a timeout.
★ When this WOULD be the correct answer
A question asking: 'Which feature should be configured to prevent a broadcast storm from overwhelming a switch port?' would make storm control the correct answer, as it limits the rate of incoming broadcast traffic.
Why candidates choose this
Candidates may confuse 'storm control' with a security feature that reacts to unauthorized devices, or they might think that disabling a port due to a storm is similar to disabling it due to a security violation.
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 port security's 'shutdown' violation mode (which triggers errdisable) and 'restrict' or 'protect' modes (which do not disable the port), leading candidates to incorrectly assume any port security mode meets the requirement for automatic re-enablement.
Detailed technical explanation
How to think about this question
Port security violation mode 'shutdown' places the port into an errdisable state, which blocks all traffic until manually or automatically recovered. The 'errdisable recovery cause psecure-violation' command and 'errdisable recovery interval <seconds>' timer allow automatic re-enablement, with a default interval of 300 seconds. This feature is configured per interface using 'switchport port-security', 'switchport port-security maximum', and 'switchport port-security violation shutdown'.
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.
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: Port security with violation mode 'shutdown' and errdisable recovery interval — Port security with violation mode 'shutdown' disables the port when an unauthorized device is detected, and the errdisable recovery interval automatically re-enables the port after a specified time period. This directly matches the auditor's requirement to disable on unauthorized connection and auto-re-enable after a timeout.
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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