Ping Monitor is a Windows application that allows you to track the availability of nodes on the Internet.
In case one of the nodes selected for monitoring is unavailable, the application can notify about this by email. If there is temporarily no access to the Internet, the letter will be sent when access appears. If you need the notification to occur in some other way, you can add the launch of your script or executable file.
For those nodes where ICMP (ping) is not available, monitoring is possible on one of the ports.
The application is completely free.