JNCIS-SP: Juniper Networks Certified Specialist – Service Provider Routing (2023) — Question 26

You are bringing a new network online with three IS-IS routers using default Junos election priorities. The routers are configured as Level 2 only IS-IS routers.

Which statement is true about the DIS election in this scenario?

Answer options

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

Correct answer: D

Explanation

The correct answer is D, as in IS-IS, the Designated Intermediate System (DIS) is elected based on the highest MAC address when all routers have the same priority. Options A and C refer to IP addresses, which are not used for DIS election, while option B incorrectly states that the lowest MAC address would be elected.