Which switch feature shuts down a port if it receives a BPDU frame?

Which switch feature shuts down a port if it receives a BPDU frame?

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

Answer: (C)

BPDU Guard protects edge ports from participating in spanning-tree. It watches for BPDU frames on ports that are typically connected to end devices (often with PortFast enabled). If a BPDU is received on such a port, the switch shuts the port down by putting it into an error-disabled state. This prevents a rogue device or misconfigured equipment from sending BPDUs and potentially altering the STP topology, which could cause loops. The port can then be re-enabled later if needed, sometimes automatically with an errdisable recovery timer. Sticky MAC is about preserving learned MAC addresses, Port Security restricts which devices can connect by MAC, and 1000BASE-T is just a physical Ethernet standard—none of these automatically shut down a port when a BPDU arrives.

BPDU Guard protects edge ports from participating in spanning-tree. It watches for BPDU frames on ports that are typically connected to end devices (often with PortFast enabled). If a BPDU is received on such a port, the switch shuts the port down by putting it into an error-disabled state. This prevents a rogue device or misconfigured equipment from sending BPDUs and potentially altering the STP topology, which could cause loops. The port can then be re-enabled later if needed, sometimes automatically with an errdisable recovery timer.

Sticky MAC is about preserving learned MAC addresses, Port Security restricts which devices can connect by MAC, and 1000BASE-T is just a physical Ethernet standard—none of these automatically shut down a port when a BPDU arrives.