How to choose the root bridge in the spanning-tree.

The correct answer is A. Highest MAC address B. Lowest Mac address. The STP root bridge election follows a two-step process: (1) The switch with the lowest Bridge Priority wins. The default priority is 32768, and it can be tuned in increments of 4096. (2) If two or more switches have identical bridge priorities, the switch with the LOWEST MAC…

Advanced Enterprise Campus Networks

Question

Options

AHighest MAC address
BLowest Mac address

How the community answered

(24 responses)

A
100% (24)

Explanation

The STP root bridge election follows a two-step process: (1) The switch with the lowest Bridge Priority wins. The default priority is 32768, and it can be tuned in increments of 4096. (2) If two or more switches have identical bridge priorities, the switch with the LOWEST MAC address becomes the root bridge. Therefore, the definitive correct answer per STP standards is the LOWEST MAC address (choice B). Choice A (Highest MAC address) is incorrect per IEEE 802.1D. This question's answer key listing both A and B appears to be an error in the source material. In practice, engineers use the 'spanning-tree vlan X root primary' command to explicitly control root placement rather than relying on MAC-address-based election.

Topics

#spanning tree#root bridge election#bridge ID#MAC address

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