JNCIS-SP: Juniper Networks Certified Specialist – Service Provider Routing (2023) — Question 18

You are bringing a new network online with three MX Series devices enabled for STP. No root bridge priority has been configured.
Which statement is true in this scenario?

Answer options

• A. The device with the lowest MAC address will be elected as the root bridge.
• B. The device with the lowest numerical lo0 IP address will be elected as the root bridge.
• C. The device with the highest MAC address will be elected as the root bridge.
• D. The device with the highest numerical lo0 IP address will be elected as the bridge.

Correct answer: A

Explanation

The correct answer is A because in the absence of a configured root bridge priority, the Spanning Tree Protocol (STP) elects the root bridge based on the lowest MAC address. Options B, C, and D are incorrect as they reference IP addresses and incorrect MAC address comparisons, neither of which is used for determining the root bridge in this situation.