For various reasons such as patch application or software installation, a server needs to be rebooted. This simple step could potentially make or break the availability of your application. Just to have a quick information when your server was rebooted can help you in troubleshooting an issue.
There are several ways to find this information.
Using Command Prompt
A quick way to do this is by executing a systeminfo command from Command Prompt within your Windows Server.
Launch Command Prompt and type in the following:
systeminfo | find "Boot Time"
There are some other variants you can see, but as far as obtaining the date and time of the server reboot, the final result is still the same.
systeminfo | find /i "Boot Time"
Using Task Manager
In Task Manager, click on the Performance tab and look for the Up time. This will involve a bit of calculation to determine the exact date and time, but you can see how long the server has been running since its last reboot.