Which spanning-tree protection feature disables ports when a violation occurs?IP source guardBPDU guardroot guardPortFast

To determine which spanning-tree protection feature disables ports when a violation occurs, let's analyze the options given:

1. IP Source Guard: This feature is used to prevent IP address spoofing. It doesn't disable ports but filters packets based on IP-MAC bindings.

2. BPDU Guard: This feature disables the port if a Bridge Protocol Data Unit (BPDU) is received on a port that should not receive BPDUs, typically configured on PortFast-enabled ports.

3. Root Guard: This feature prevents a designated port from becoming a root port if it receives BPDUs indicating a higher bridge priority. However, it does not immediately disable the port; rather, it prevents a topology change.

4. PortFast: This feature allows a port to transition to the forwarding state immediately when an interface becomes active, bypassing the listening and learning states. It does not disable ports in the event of a violation.

Final Answer

BPDU Guard is the spanning-tree protection feature that disables ports when a violation occurs.