The first two can be handled by firewall. Little Snitch for example: https://obdev.at/products/littlesnitch/index.html. Source: over 1 year ago

If you want more control over outgoing traffic, there’s commercial stuff like Little Snitch or the similar free tool LuLu from Objective-See. Source: almost 2 years ago

Objective Development's Little Snitch. It's been the first piece of software I've installed on every Mac I've owned in the last 20 years. Source: over 2 years ago

Little Snitch? https://obdev.at/products/littlesnitch/index.html. Source: almost 3 years ago

If you want to block it at the network/DNS level you could edit the hosts file or use something like Little Snitch to monitor (and block) outgoing connections. Source: about 3 years ago

Have a look at bping http://gizmoware.net/bping/ you don't even have to keep an eye on it, you can set it to one of two settings, sound on error or sound on resolve. So if you have a server that is always on, you can set it to beep when the server goes off, or you can set it to make a sound when the device comes back online. I have it on hand when I am restarting things and don't have to "watch" for it to come... Source: almost 2 years ago