Speed of lan NIC

10/100 is the possible operation speed of the given network device. Meaning, it'll operate at 10mbps, or 100mbps. It differs if you use an old hub or switch that doesnt support 100, it will then use 10. Most things today are 10/100/1000 -- This is possible because even though the technology has evolved, the medium it runs on for the most part is the same, thus allowing backward compatibility with older network equipment

thaank you thekurrgan.
means this 10/100 is just de choice (either 10 or 100) that device automatically select accordin to its architechure.