With which command can you determine the time of the last restart of a system?

'current reboottime' is not a valid Linux command and does not exist on standard systems.

'find reboot' is not a valid command syntax; 'find' is used for locating files by attributes, not querying system uptime records.

'expect --reboot' is not a valid usage; 'expect' is a scripting tool for automating interactive programs, not for querying reboot history.

'last | reboot' pipes the output of 'last' into 'reboot', which would attempt to restart the system, not display reboot history.

The 'last' command reads /var/log/wtmp and displays login/reboot records. When given 'reboot' as an argument, it filters output to show only reboot events, including the timestamp of each. This is the standard Linux method for determining when the system was last restarted.