The answer is port security with violation mode 'shutdown' and the errdisable recovery interval. This combination directly meets the auditor’s requirement because when an unauthorized device is detected, the switch port is placed into an errdisable state, effectively shutting it down, while the errdisable recovery interval automatically re-enables the port after a user-defined timeout. On the CompTIA Network+ N10-009 exam, this scenario tests your understanding of how port security violation modes differ—specifically, that 'shutdown' triggers errdisable, whereas 'restrict' or 'protect' do not. A common trap is confusing 'shutdown' with 'protect', which drops traffic but leaves the port administratively up. Remember the memory tip: “Shutdown sends it to errdisable; recovery brings it back on schedule.”
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?
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.
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.
✓
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.
✗
Storm control and broadcast suppression
Why it's wrong here
These control traffic storms, not unauthorized device access.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco 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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this N10-009 question in full detail.
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.
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