When you start the NUCs there is a program that is called "autostart". This program requests a password or, if you connect to the main PC, is connected via a ssh connection. The program will ask the main PC if there is a new software version for the NUCs and after a potential update it forces the NUCs to give a feedback every second to the main PC in the way of " I am online (ID)", where it identifies its ID via its own IP. if this alive-signal is not sent for a specified period of time, the LCC will mark this NUC as offline.