The answer is that the workstation is sending traffic with multiple source MAC addresses. This is the most likely cause because the port-security configuration sets a maximum of two MAC addresses with a violation mode of shutdown, meaning the switch port goes err-disabled the moment it detects more than two unique source MACs—even if only one physical device is connected. On the ISC2 Certified in Cybersecurity CC exam, this scenario tests your understanding of how port security violation cause err-disabled states, often disguising a virtual machine host or a downstream switch as a single workstation. A common trap is assuming the device itself is faulty, when in reality the switch is enforcing the MAC address limit. Remember the mnemonic: “One device, many MACs—err-disabled attacks.”
ISC2 CC Network Security Practice Question
This CC practice question tests your understanding of network security. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
Refer to the exhibit. A network administrator configured the above on a switch port. After connecting a single workstation, the port goes into err-disabled state within minutes. What is the most likely cause?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The workstation is sending traffic with multiple source MAC addresses.
The port-security configuration with a maximum MAC address count of 2 and violation mode 'shutdown' causes the port to err-disable when a single workstation sends traffic with multiple source MAC addresses. This is a classic symptom of a device (e.g., a virtual machine host or a switch behind the port) generating frames from different MACs, exceeding the allowed limit and triggering the violation.
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.
✓
The workstation is sending traffic with multiple source MAC addresses.
Why this is correct
Exceeding the maximum MAC count triggers violation shutdown.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The port-security maximum is set to 2, so it should allow up to 2 MACs; the issue is elsewhere.
Why it's wrong here
If the workstation sends more than 2 MACs, it will still violate the limit.
✗
Sticky MAC learning is disabled.
Why it's wrong here
The command shows 'sticky' is enabled, so that is not the issue.
✗
The violation mode should be 'restrict' instead of 'shutdown'.
Why it's wrong here
Restrict would not cause shutdown, but the issue is exceeding the MAC limit.
Common exam traps
Common exam trap: answer the scenario, not the keyword
ISC2 often tests the misconception that the maximum MAC count is the only factor, when in reality a single device can generate multiple MAC addresses (e.g., via virtualization or bridging), causing a violation even with a seemingly generous limit like 2.
Trap categories for this question
Command / output trap
The command shows 'sticky' is enabled, so that is not the issue.
Detailed technical explanation
How to think about this question
Port-security uses a MAC address table per interface, and when the number of dynamically learned MACs exceeds the configured maximum, the configured violation action (shutdown, restrict, or protect) is triggered. In this scenario, the workstation is likely a virtual machine host or a device with multiple NICs, causing frames with different source MACs to be sent, which rapidly fills the allowed MAC table and triggers the shutdown. The err-disabled state can be recovered by issuing 'shutdown' followed by 'no shutdown' on the interface, but the underlying cause must be addressed.
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 security analyst at a medium-sized enterprise encounters this scenario during an investigation or architecture review. The correct answer reflects best practice for the specific threat or control described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Security exam questions test whether you can match controls to threats in context — not just recall definitions.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CC 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: The workstation is sending traffic with multiple source MAC addresses. — The port-security configuration with a maximum MAC address count of 2 and violation mode 'shutdown' causes the port to err-disable when a single workstation sends traffic with multiple source MAC addresses. This is a classic symptom of a device (e.g., a virtual machine host or a switch behind the port) generating frames from different MACs, exceeding the allowed limit and triggering the violation.
What should I do if I get this CC question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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 →
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A security administrator is concerned about MAC address spoofing on the network. Which technology can help mitigate this risk by associating a specific MAC address with a port?
medium
✓ A.Port security
B.Dynamic ARP inspection
C.DHCP snooping
D.VLAN hopping prevention
Why A: Port security is the correct answer because it directly mitigates MAC address spoofing by allowing an administrator to statically or dynamically associate a specific MAC address with a switch port. When a device with a different MAC address attempts to use that port, port security can either disable the port (errdisable) or drop the traffic, preventing unauthorized access. This is a Layer 2 security feature that enforces MAC-to-port binding.
Last reviewed: Jun 30, 2026
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This CC practice question is part of Courseiva's free ISC2 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 CC exam.
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