My Nest thermostat calls home every five minutes. Not my home, but its home, it calls back to nest.com at least every five minutes. Now I have these nice reports of the network traffic (what is being blocked and what is being allowed) I can see what all the devices are up to. Any that are sending requests directly to an ip address I will not see, but anything that has to use DNS to work out where it's off to, I've got my eye on you.
OK only one thing I have learned actually I'm sure there's more to come.