As shown in the figure, SW1 is the general root in the MSTP network, please configure the following switches with the IST domain root and main bridge.

Question

Options

• AThe correct configuration is: SW1 is both the root of the IST domain and the main bridge; SW2, SW4, SW6 are neither the IST domain root nor the main bridge; SW3 is the main bridge.
• B
• C
• D

• A
  80% (24)
• B
  7% (2)
• C
  3% (1)
• D
  10% (3)

Explanation

Option A is correct because in MSTP, the switch designated as the general root (CST root) automatically becomes both the IST root and the main bridge (regional root) for its own MST region - SW1 holds all three roles simultaneously. SW3 is correctly identified as a main bridge because it resides in a different MST region and serves as that region's representative (regional root) toward the CST root SW1. SW2, SW4, and SW6 are ordinary switches within their regions with no elevated role in the IST or CST topology, making any option that assigns them special bridge roles incorrect.

Memory tip: Think of the general root as the "triple crown" holder in its own region - CST root, IST root, and main bridge all at once. Every other region that connects back to it will have exactly one main bridge, which is the switch with the best path to the general root.

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