While reviewing an existing network design, you are discussing the characteristics of different STP versions. Which protocol minimizes unicast flooding during TCN in a Layer 2 switched network with…

Classic STP (802.1D) maintains one instance for the entire network, so any TCN triggers a global MAC table flush that causes unicast flooding across all VLANs at the same time.

MST groups multiple VLANs into a smaller number of instances, meaning a TCN in one instance simultaneously impacts all VLANs mapped to that instance and can cause flooding across more VLANs than PVSTP+ would.

PVRSTP+ (Rapid PVST+) uses an aggressive TC mechanism that immediately flushes MAC address entries on all non-edge ports upon receiving a TCN, producing a more intense burst of unicast flooding than PVSTP+'s timer-based aging approach.

PVSTP+ runs a separate spanning tree instance per VLAN, so a TCN and its resulting MAC table impact are contained to only the affected VLAN, preventing a single event from triggering flooding across all VLANs simultaneously. Unlike Rapid STP variants, PVSTP+ handles TCN by shortening the MAC address aging timer rather than immediately flushing all non-edge-port entries, which reduces the instantaneous burst of unicast flooding.