You are required to ensure that Switch 1 will always be designated as the root bridge when participating in your switched network. What do you need…

In the Spanning Tree Protocol (STP), the root bridge is determined by the lowest Bridge ID. The Bridge ID is a 64-bit value consisting of a 16-bit bridge priority and a 48-bit system MAC address. Because the bridge priority is the most significant portion of the Bridge ID, configuring a switch with the lowest bridge priority (e.g., 0 or 4096) guarantees that it will win the election and always be designated as the root bridge, regardless of its MAC address.

- A: STP prefers the lowest system MAC address, not the highest, and bridge priority takes precedence over the MAC address anyway.

- C: Port priority is used to determine the root port on non-root bridges, not to elect the root bridge itself.

- D: Port costs are used to calculate the shortest path to the root bridge, not to elect the root bridge.

- Juniper Networks. "Spanning Tree Protocol User Guide." Understanding STP, RSTP, and MSTP, Section: Root Bridge Election.

- IEEE 802.1D-2004. "IEEE Standard for Local and metropolitan area networks - Media Access Control (MAC) Bridges." Section 17: Rapid Spanning Tree Protocol.