Why the Scan IP function cannot scan machines that located outside my LAN?
A. Scan IP function sends ICMP echo request to destination to verify whether an IP is in use or active. However, many attacks and worm viruses also used ICMP widely. So hardly all the routers on LAN and WAN had to filter ICMP traffic. This is why Scan IP function frequently failed to scan other subnet. Now you can turn on the scan option “Skip ping while scanning IP” and it helps you retrieve more targets from other subnet, but this would slow down the speed.
