You have been given a server where Nginx is crashing. Where will you start?

First, gather information about the problem:

1. Check Nginx logs — usually error.log and access.log, they will give clues about the causes of the crash.
2. Check the service status: systemctl status nginx or service nginx status.
3. Verify if configuration files have been recently changed — you can run nginx -t to check syntax.
4. Assess server load: CPU, memory, disk space — the crash may be related to resources.
5. If there is a core dump or crash log, analyze them.
6. Try restarting the service and see if the error recurs.

Thus, diagnostics start with analyzing logs and service status, then check configuration and system resources.