Which state indicates that a port is not forwarding traffic but can receive BPDUs?

When a port is in the blocking state, it signifies that the port is not participating in the active data forwarding and is effectively blocking traffic. However, during this state, the port is still able to receive Bridge Protocol Data Units (BPDUs). BPDUs are essential for maintaining the spanning tree topology and ensuring that the network remains loop-free.

In contrast, the other states have different functions:

• A disabled state signifies that the port is completely shut down and does not send or receive any traffic, including BPDUs.

• Listening is a state where the port is preparing to participate in data forwarding but is not yet actively forwarding frames. It will still receive BPDUs, but it is not in a blocking position concerning forwarding traffic.

• Learning is the state during which the port is learning MAC addresses and populating its MAC address table but has not yet transitioned to forwarding state. Although it is aware of which addresses are in the network, it is not yet forwarding traffic either.

The definition of each state reveals how the blocking state is unique in its ability to receive BPDUs while still preventing traffic forwarding, thus confirming that this state is correctly identified in the context of Spanning Tree Protocol (STP).