A comparator according to the present invention can generate an output signal of low or high level by comparing a first and second input voltages that have a common voltage. The notification may include information such as the address of the infected system, identification of the specific worm, and a list of vulnerable applications and operating systems. Normally, the inputoutput cards, which are connected to the node device, are required to divide the address space of the node device among each other. After the removal of the bolts, the plate is separated from the spacer bar.