Working on servers, you inveriably need to reboot them. One of the primary tools I use to determine if a server has shut down is to PING the server.
PING servername -t
This will PING the server repeatedly until I quit it. When the server goes down, it will return "Request Timed Out" instead of a valid PING response. Here is what it would look like when the server shuts down, then comes back up again.