It has sensors that cut the heat off and push the toast out. At the most complex level, computers can store massive amounts of information and can provide instant access to it. So at this very basic level of "knowing" many machines already do know.
Turning to the third definition of knowing, do any machines "recognize or distinguish in comparison". Again, the answer is yes. A car can recognize a whole host of complex facts, from the road conditions, to the air temperature to its own state of repair. It distinguishes a full gas tank from an empty fuel tank and acts upon the information through providing a warning light for the driver. The car distinguishes a door being closed from a door being open, and will beep when a door has been left ajar. The car, or rather the computer within its engine, is distinguishing between one situation and another.
So the third definition seems to have been met. But perhaps the most important question is whether a machine does or ever will be able to "perceive". Essentially this is a questions that deals with whether a machine will ever be able to "think". Will we turn on a computer one day and have it say "hullo, I am here", and know that it is saying it. Thus the basic question is whether a machine will ever be alive.
The idea of a thinking computer, with all the benefits and risks involved, ...