Say you have a router with 2 interfaces:
1 – WAN and 1 – LAN. The LAN interface is connected to 10/100 switch. This router and LAN are physically located together in California.
The router is working fine, no problems. From your NY location, you can ping the router’s WAN interface fine, ping the LAN interface fine, and you can remote access hosts on the California LAN.
If you unplug the CAT5 patch cable that goes from the California Router’s LAN interface to the local LAN switch, and you try and ping the Router’s LAN interface, from your NY location, will you get a good reply?
Obviously, you will not get a good ping response from any hosts on the California LAN, but what about the router LAN interface itself? It is still up and operational, it is just unplugged from the LAN switch.
