Readers who are not familiar with IP routing should read my December 1996 column. I will also be discussing the loopback interface. It resides in one of two places. Interfaces Network interfaces are the mouth and ears of a network node.
Interfaces can be network cards, serial ports and parallel ports.
The IP loopback interface is a unique interface in that it connects to itself. Packets sent to the loopback interface are simply reflected back to the IP stack which then sees them as incoming packets. This interface is used mainly for testing. The standard host name for this interface is 'localhost'. This calls the PING application which will test the network path between to the indicated hosts.