Cisco ENCOR Practice Exam 2026 – All-in-One Comprehensive Guide to Mastering Enterprise Network Core Technologies!

In Spanning Tree Protocol (STP), the Non-Designated port role is responsible for blocking traffic. This role applies to ports that are not designated to forward traffic to prevent loops in the network topology. In an STP-converged network, each switch port can assume a role, and ports that are not selected to be the designated port for a particular network segment will be put in blocking state to ensure only one active path exists.

The Non-Designated ports listen for BPDUs (Bridge Protocol Data Units) but do not forward frames until they transition to a forwarding state, typically if a designated port goes down or the network topology changes. This behavior is essential for maintaining a loop-free network design by restricting the flow of traffic on redundant paths.

The Root port and Designated port have roles that allow them to actively forward traffic in the network. The Root port is the port on a switch that has the lowest cost path to the root bridge, while the Designated port is responsible for forwarding traffic towards the root bridge for a specific network segment. The Active role does not specifically correlate with a defined term in STP; it typically refers to ports that are forwarding and participating in the network rather than being in a blocking state.