In STP, what are the typical port roles and what do they indicate?

• A. Access Port, Trunk Port, Edge Port.
• B. Root Port, Secondary Port, Tertiary Port.
• C. Designated, Backup, Forwarding.
• D. Root Port (best path to root), Designated Port (forwarding on a segment), and Blocking Port (prevents loops).

Answer: (D)

Spanning Tree Protocol assigns each switch port a role to keep a loop-free topology. The main ideas are that there is a root bridge with no root port, every non-root switch selects one port as the best path toward the root (the root port), and on each network segment one switch port is chosen to forward toward that segment (the designated port). All other ports on that segment are placed in a blocking state to prevent loops. The combination of these roles is exactly what the correct option describes: a root port that represents the best path to the root, a designated port that forwards onto a segment, and a blocking port that prevents potential loops. The other options mix terms from VLAN port types or states that aren’t used as standard STP port roles, so they don’t accurately capture how STP identifies and uses port roles.