What is the likely cause?

A security engineer received multiple reports of an IPSec VPN tunnel going down the night before. The engineer couldn’t find any events related to VPN under system togs.

What is the likely cause?
A . Dead Peer Detection is not enabled.
B. Tunnel Inspection settings are misconfigured.
C. The Tunnel Monitor is not configured.
D. The log quota for GTP and Tunnel needs to be adjusted

Answer: C

Explanation:

This means that the firewall does not have a mechanism to monitor the status of the IPSec VPN tunnel and generate logs when it goes down or up. The Tunnel Monitor is an optional feature that can be enabled on each IPSec tunnel interface and it uses ICMP probes to check the connectivity of the tunnel peer. If the firewall does not receive a response from the peer after a specified number of retries, it marks the tunnel as down and logs an event1.