What are the options for remotely determining the status of a computer?

Question

Remote access

Good afternoon!
There are several windows computers with Internet access.
You need a service, preferably a web one, in which you can see whether computers are turned on or off.
The computers are not connected via the local network; poll status only on the Internet.
Teamviewer thought to use, it basically shows which computers are on the network, but if teamviewer is closed, the computer will be "off". And it doesn't suit me.

Answer 1

logmein and the client to autoload.
In any case, something will have to be launched on the side of the machines. Or add a pingalka to the scheduler.

Answer 2

teamviewer set the launch and in the settings prohibit the client from shutting down.

Answer 3

If you know the addresses of the machines, then send an ICMP request. Use ping or Nmap using the -sP option .

Answer 4

www.kilievich.com/rus/fpinger
Display which computers are on and which are not;
Ping all devices at once;
Notification in case of server stop/start;