This article explain the Kernel Crash with RE reboot reason as "Last reboot reason:- panic:integer divide fault"

In a very rare circumstances, DDoS policers (enabled by default on Trio based line cards from 11.2) might cause kernel panic.

The following message might be seen:

  eventd[1069]: SYSTEM_ABNORMAL_SHUTDOWN: System abnormally shut down

  eventd: sendto: No route to host

  eventd[1069]: SYSTEM_OPERATIONAL: System is operational

  savecore: reboot after panic: integer divide fault     <<<<<<<<<<

  savecore: writing core to vmcore.0

This was found out to be a bug in Kernel and DDOS module code creating a time wrap and causing this zero divide. 

  There is extremely low probability to see the issue. If so get the fix of the PR https://prsearch.juniper.net/problemreport/PR952756