Understanding PXE and Windows

Earlier today, I began reading Using PXE Boot Technologies to Install Windows over a Network but stopped when I hit this passage:

That hadn't been a problem, as Microsoft IT always required pressing F12 to PXE boot, but this PXE server did not have a delay, an F12 prompt, or any type of notification. This meant that the executive effectively lost his computer and any data not protected by his Roaming User Profile.

Anyone who thinks the F12-to-net-boot query comes from an install server instead of a machine's boot sequence simply can't know enough about the procedure to be of any help.  I love how the TFTP server randomly just contacts the target machine out of the blue.

I wasn't going to stay long - since a boot server that doesn't play nice with anyone else, in typical MS fashion, is really of no value in the real world - but this just made it quicker.