List the steps STP uses in selecting the designated port?

STP is Protocol used in Switches.

STP will initially choose the Root Bridge. All ports of the Root Bridge will be Designated ports.

The non-Root Bridge Switches, will have to reach Root Bridge. The shortest path (Interface) to reach the Root-Bridge is Root-port.

The Reamining ports in non-Root Bridges, will be elected either as a Designated port of Alternate port.

The Non-Root Bridge Switches with the best Bridge ID (Priority & Mac-Addres ) will be Designated port and the Other End of the Switch will become Alternate port (Blocked mode ).

Lowest Bride ID. After selecting root bridge. Below steps should be follow

Lowest path cost

lowest sender bridge id

lowest port id

After selecting Root Port, the port that doesn't block anf able to forward data is designated port.

lowest root bid

lowest rpc to root bridge

lowest sender bid

lowest sender port id