An engineer is analyzing a ticket for an unexpected server shutdown and discovers that the...

The most relevant log for system-level events such as memory exhaustion and shutdown is/var/log/messages.log, which contains kernel and service-level logs including OOM (Out-Of-Memory) events.

As detailed in Linux investigations:

"Logs located in/var/log/messagesprovide critical system error reporting including shutdowns, memory errors, and service failures".