i had Ubuntu 16.04 installed on AWS EC2, i was able to connect to it using Putty in the past, but before couple of days, i was unable to connect to the server using the Putty.
when i checked the instance from AWS console management i found out that it's CPU utilization was 100% for a long time and not going down, i have restarted the instance and its started again fine.
the question is, how can i know what happened? is there some sort of a log, or a way to know what happened exactly? since i don't want this issue to reappear in the future