Question

you are a network administrator tasked with configuring a new network that includes several switches. youve decided to use spanning tree protocol (stp) to prevent network loops. one of the switches is connected to the networks high-bandwidth backbone, and you want to ensure this switch is elected as the root bridge.

which of the following actions should you take?

a set the same priority value for all switches in the network.
b decrease the priority value of the switch connected to the high-bandwidth backbone.
c increase the priority value of the switch connected to the high-bandwidth backbone.
d disable stp on all switches except the one connected to the high-bandwidth backbone.

Explanation:

Analyze the root bridge election process

In the Spanning Tree Protocol (STP), the root bridge serves as the logical center of the network topology. Switches elect a root bridge based on the Bridge ID (BID), which consists of a configurable bridge priority value and the switch's MAC address. The switch with the lowest BID is elected as the root bridge.

Determine the effect of priority values

Because the election criteria favors the lowest BID, a lower bridge priority value increases a switch's likelihood of becoming the root bridge. By default, most switches have a priority of 32768. To guarantee that a specific high-bandwidth backbone switch is elected, its priority value must be manually decreased to a value lower than all other switches in the network (such as 4096 or 0).

Evaluate the given options

• Option A: Setting the same priority value for all switches forces the election to rely on the lowest MAC address, which is random and does not guarantee the backbone switch is chosen.
• Option B: Decreasing the priority value of the backbone switch ensures it has the lowest BID, guaranteeing its election as the root bridge.
• Option C: Increasing the priority value makes it less likely to be elected.
• Option D: Disabling STP on other switches would create network loops on those paths, defeating the purpose of loop prevention.

Answer:

• (A) Set the same priority value for all switches in the network.
• (B) Decrease the priority value of the switch connected to the high-bandwidth backbone. (Correct answer)
• (C) Increase the priority value of the switch connected to the high-bandwidth backbone.
• (D) Disable STP on all switches except the one connected to the high-bandwidth backbone.