Which port security feature automatically learns and saves the MAC address of the first device connected to a port?

Which port security feature automatically learns and saves the MAC address of the first device connected to a port?

• A. Port Security
• B. BPDU Guard
• C. 1000BASE-T
• D. Sticky MAC

Answer: (D)

Port security includes a mode that automatically learns and saves the MAC address of the first device that connects to a port. This is Sticky MAC. When you enable port security with sticky MAC, the switch observes the first frame from the connected device, records that device’s MAC address, and stores it as a sticky entry in the running configuration. If you save the configuration, the MAC address becomes persistent across reboots, so the same device can reconnect without being blocked. This differs from purely dynamic port-security entries, which are learned at runtime but don’t necessarily persist after a reboot unless saved, and from static MAC configurations which require manual entry. BPDU Guard and 1000BASE-T aren’t about learning or saving MAC addresses, so they don’t fit this function.

Port security includes a mode that automatically learns and saves the MAC address of the first device that connects to a port. This is Sticky MAC. When you enable port security with sticky MAC, the switch observes the first frame from the connected device, records that device’s MAC address, and stores it as a sticky entry in the running configuration. If you save the configuration, the MAC address becomes persistent across reboots, so the same device can reconnect without being blocked. This differs from purely dynamic port-security entries, which are learned at runtime but don’t necessarily persist after a reboot unless saved, and from static MAC configurations which require manual entry. BPDU Guard and 1000BASE-T aren’t about learning or saving MAC addresses, so they don’t fit this function.