During STP root port selection, which criterion is considered first?

The first criterion for root port selection is the lowest path cost to the root bridge. A switch calculates the cumulative cost of all links along the path to the root bridge and chooses the port with the lowest total cost. If multiple paths have the same lowest cost, the switch then considers the lowest neighbor's bridge ID. If still tied, it looks at the lowest neighbor's port ID. Finally, if all previous criteria are identical, the local port ID is used as a tie-breaker. Therefore, path cost is the primary factor in determining the root port.