JNCIA-Junos: Juniper Networks Certified Associate – Junos — Question 15

A packet enters a Junos device. No matching destination entry exists in the forwarding table.
How will the device respond?

Answer options

• A. The RE responds to the destination with a source unreachable notification message.
• B. The RE responds to the source with a destination unreachable notification message.
• C. The PFE responds to the destination with a source unreachable notification message.
• D. The PFE responds to the source with a destination unreachable notification message.

Correct answer: B

Explanation

The correct answer is B because when there is no matching destination entry, the Routing Engine (RE) sends a destination unreachable notification back to the source of the packet. Options A and C incorrectly state the direction of the notification, while option D incorrectly attributes the notification to the Packet Forwarding Engine (PFE) instead of the RE.