Function of "switchport port-security mac-address sticky"

E.

The command "switchport port-security mac-address sticky" is used in Cisco IOS-based switches to configure port security on a switch port, and it performs a specific function.

Port security is a feature that allows the switch to restrict the number of MAC addresses that can be learned on a particular switch port. The switchport port-security mac-address sticky command enables sticky learning for port security.

Here is what the command does in detail:

1. The command configures the switch port for port security.
2. The "mac-address" keyword specifies that the MAC addresses learned on the switch port should be secured.
3. The "sticky" keyword tells the switch to dynamically learn the MAC addresses on the switch port and add them to the running configuration as static secure MAC addresses.
4. When the "sticky" keyword is used, the dynamically learned MAC addresses are copied from the MAC address table (CAM table) to the startup configuration, which means that they are saved even if the switch is restarted.
5. The "sticky" keyword is useful in situations where the network administrator wants to secure the switch port against unauthorized devices, but wants to avoid manually configuring the secured MAC addresses on the switch port.

Therefore, the correct answer is D: It allows the switch to perform sticky learning, in which the dynamically learned MAC addresses are copied from the MAC address table (CAM table) to the startup configuration.