CompTIA Network+ (N10-009)Network ImplementationMedium
A network administrator configures port security on a switch access port, setting the maximum MAC address count to one and the violation action to shutdown. A user later connects a small unmanaged hub to that port and attaches two additional devices. What is the expected result?
- AThe switch automatically creates a new VLAN for the extra devices
- BThe switch silently drops frames from the extra MAC addresses only
- CThe port transitions to an err-disabled state
- DThe port forwards traffic from all connected devices normally
Show answer & explanationAnswer & explanation
Correct answer: C. The port transitions to an err-disabled state
When port security detects more MAC addresses than the configured maximum and the violation mode is set to shutdown, the switch immediately places the port into an err-disabled state, blocking all traffic until an administrator manually re-enables it.
Why the other options are wrong
- A. Switches do not dynamically create VLANs in response to port security violations.
- B. Silently dropping only extra MACs describes the 'restrict' or 'protect' violation modes, not shutdown.
- D. This would only occur if the violation mode were set to protect, not shutdown.
Port Security Violation Modes
A switch security feature limiting the number of MAC addresses allowed on a port; violation actions include protect (drop silently), restrict (drop + log), and shutdown (err-disable the port).
- Shutdown mode disables the port and requires manual/automatic re-enable
- Protect mode drops excess traffic without logging
- Restrict mode drops excess traffic and logs/counts violations
Memory trick: Shutdown mode = slam the door shut on violations.