Question 1mediummultiple choice
Full question →mediummultiple choiceObjective-mapped
Exhibit
SW1# show port-security interface gi1/0/5 Port Security : Enabled Port Status : Secure-up Violation Mode : Restrict Maximum MAC Addresses : 2 Current MAC Addresses : 2
Exhibit: Port security is enabled with a maximum of 2 MAC addresses, but a third device connected through a small hub causes a violation. Which result is expected in restrict mode?
Answer choices
Why each option matters
Good practice is not just finding the correct option. The wrong answers often show the exact trap the exam wants you to fall into.
A
Distractor review
The port goes immediately to err-disabled state
That behavior is associated with shutdown mode.
B
Best answer
Frames from the unknown MAC are dropped and the violation is counted
That is the purpose of restrict mode.
C
Distractor review
The switch learns the third MAC after 30 seconds automatically
That would defeat the configured maximum.
D
Distractor review
STP blocks the port until the MAC table ages out
STP is not what enforces port security.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A frequent exam trap is selecting the shutdown mode behavior for a question about restrict mode. Many candidates mistakenly believe that any port security violation immediately disables the port, but restrict mode only drops unauthorized frames and increments violation counters without shutting down the port. This confusion arises because shutdown mode is the most severe response and is often the default in examples. Another trap is assuming that Spanning Tree Protocol (STP) blocks the port during violations, but STP is unrelated to port security enforcement. Recognizing the distinct behaviors of violation modes is critical to answering correctly.
Technical deep dive
How to think about this question
Port security is a Layer 2 security feature on Cisco switches that restricts input to an interface by limiting and identifying MAC addresses of the stations allowed to access the port. This feature is essential in preventing unauthorized devices from connecting to the network through physical access points. When enabled, the switch learns MAC addresses up to a configured maximum and enforces policies when violations occur, such as when an unknown MAC address attempts to send frames through the port. The behavior of port security upon a violation depends on the configured violation mode. In restrict mode, the switch drops frames from any MAC address that exceeds the maximum allowed and increments a violation counter, but the port remains active and forwarding. This mode allows network administrators to monitor violations without disrupting network connectivity. In contrast, shutdown mode immediately disables the port by placing it into an err-disabled state, requiring manual recovery. The protect mode silently drops violating frames without incrementing counters or disabling the port. A common exam trap is confusing restrict mode with shutdown mode. Restrict mode does not disable the port but only drops unauthorized frames and counts violations, which is less disruptive in environments where uptime is critical. Additionally, when multiple devices connect through a hub to a single port, each device's MAC address counts toward the port security maximum, potentially causing violations if the limit is exceeded. Understanding these behaviors helps in designing secure and resilient network access policies aligned with Cisco CCNA security fundamentals.
KKey Concepts to Remember
- Port security on Cisco switches limits the number of MAC addresses learned on a switch port to prevent unauthorized device access.
- In restrict mode, port security drops frames from unknown MAC addresses exceeding the maximum limit and increments the violation counter without disabling the port.
- Shutdown mode causes the port to enter an err-disabled state immediately upon a security violation, requiring manual intervention to re-enable.
- Port security violation counters help network administrators monitor unauthorized access attempts and enforce security policies effectively.
- Spanning Tree Protocol (STP) does not enforce port security violations; it manages loop prevention and port states independently.
- When multiple devices connect through a hub to a port with port security, all MAC addresses count toward the maximum allowed, potentially causing violations.
- Port security does not automatically learn new MAC addresses beyond the configured maximum, preventing unauthorized devices from gaining access.
- Restrict mode provides a balance between security enforcement and network availability by dropping unauthorized frames but keeping the port operational.
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.
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More questions from this exam
Keep practising from the same exam bank, or move into a focused topic page if this question exposed a weak area.
Question 1
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Question 2
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Question 3
What is the OSPF metric called?
Question 4
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Question 5
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Question 6
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FAQ
Questions learners often ask
What does this 200-301 question test?
Port security on Cisco switches limits the number of MAC addresses learned on a switch port to prevent unauthorized device access.
What is the correct answer to this question?
The correct answer is: Frames from the unknown MAC are dropped and the violation is counted — In restrict mode, the switch drops frames from unknown source MAC addresses and increments the violation counter, but the port stays up. That is less disruptive than shutdown mode.
What should I do if I get this 200-301 question wrong?
Then try more questions from the same exam bank and focus on understanding why the wrong options are tempting.
Discussion
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