The classic Spanning Tree Protocol (802.1 D 1998) uses which sequence of variables to
determine the best received BPDU?

A.
1) lowest root bridge id, 2) lowest sender bridge id, 3) lowest port id, 4) lowest root path cost

B.
1) lowest root path cost, 2) lowest root bridge id, 3) lowest sender bridge id, 4) lowest sender
port id

C.
1) lowest root bridge id, 2) lowest sender bridge id, 3) lowest root path cost 4) lowest sender
port id

D.
1) lowest root bridge id, 2) lowest root path cost, 3) lowest sender bridge id, 4) lowest sender
port id

Explanation:
Configuration bridge protocol data units (BPDUs) are sent between switches for each port.
Switches use a fourstep process to save a copy of the best BPDU seen on every port. When a
port receives a better BPDU, it stops sending them. If the BPDUs stop arriving for 20 seconds
(default), it begins sending them again.
Step 1 Lowest Root Bridge ID (BID)
Step 2 Lowest Path cost to Root Bridge
Step 3 Lowest Sender BID
Step 4 Lowest Port ID

Cisco General Networking Theory Quick Reference Sheets