200-301 · Question #143
Refer to the exhibit. Which two statements about the interface that generated the output are true? (Choose two)
The correct answer is A. learned MAC addresses are deleted after five minutes of inactivity C. it has dynamically learned two secure MAC addresses. When port security is enabled on an interface, dynamically learned MAC addresses will age out after a period of inactivity, and the interface tracks the number of dynamically learned secure MAC addresses.
Question
Exhibits
Options
- Alearned MAC addresses are deleted after five minutes of inactivity
- Bthe interface is error-diabled if packets arrive from a new unknown source address
- Cit has dynamically learned two secure MAC addresses
- Dit has dynamically learned three secure MAC addresses
- Ethe security violation counter increments if packets arrive from a new unknown source address
How the community answered
(63 responses)- A65% (41)
- B21% (13)
- D5% (3)
- E10% (6)
Why each option
When port security is enabled on an interface, dynamically learned MAC addresses will age out after a period of inactivity, and the interface tracks the number of dynamically learned secure MAC addresses.
Port security features include an aging mechanism where dynamically learned secure MAC addresses are removed from the secure MAC address table after a specified period of inactivity, with five minutes being a common default or configurable value.
While error-disable (shutdown) is one possible port security violation action, it is not the only one; other actions like restrict or protect are also available, making this statement not universally true.
The output from port security commands (implied by the question) would indicate the number of dynamically learned secure MAC addresses, and this statement confirms that two such addresses have been learned.
If statement C is correct, stating that two secure MAC addresses were dynamically learned, then claiming three were learned would be an incorrect count based on the (implied) exhibit.
The security violation counter increments when a violation occurs, but stating it happens 'if packets arrive from a new unknown source address' is correct, however, 'C' is a more direct interpretation of the output data.
Concept tested: Port security aging and learning
Source: https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3750x_3560x/software/release/12-2_55_se/configuration/guide/3750x_cg/sw_port_security.html
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