Does a network map show devices that never send any traffic?
No. A passive network map only knows devices that send something on a monitored segment, so a completely silent device stays invisible. In practice very few devices are fully silent: most request an address, resolve names, look for updates or answer the network now and then, so they appear within hours or days. The ones that do not are usually switched off, unplugged, on a segment you do not mirror, or deliberately quiet. To close that gap, compare the map with other sources: the switch's table of connected ports, the DHCP server's leases, your purchase records and a walk through the building. Active scanning finds silent devices that answer when asked, but use it carefully on printers and industrial equipment. NetSenX builds its network map passively on every plan and never probes devices, which is safe for fragile equipment and means a silent device is not on the map.