What is a loopback address?
The loopback address allows for a reliable method of testing the functionality of an Ethernet card and its drivers and software without a physical network. It also allows information technology professionals to test IP software without worrying about broken or corrupted drivers or hardware.
To test a network card using the loopback address, you can use the TCP/IP utility Ping. The best way to do this is with the Ping utility that comes with most operating systems. This is a simple command-line utility that will try to communicate to an IP address.
Once you are at a command prompt, enter the following:
ping 127.0.0.1
If the command is successful, the Ping utility will return results similar to the following. The exact information returned will vary depending on your operating system:
Pinging 127.0.0.1 with 32 bytes of data:
Reply from 127.0.0.1: bytes=32 time<10ms TTL=128
Ping statistics for 127.0.0.1:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 0ms, Maximum = 0ms, Average = 0ms
This indicates that the network card and drivers are functioning properly. If the Ping utility is not able to get a return on the network card, this may indicate either a driver problem, or a physical problem with the card. </div>