A. 127.0.0.1
B. 127.0.1.0
C. 127.0.1.1
D. 127.0.0.0

Solution

A. 127.0.0.1

Explanation

A loopback address is a special IP address, 127.0. 0.1, reserved by InterNIC for use in testing network cards. This IP address corresponds to the software loopback interface of the network card, which does not have hardware associated with it, and does not require a physical connection to a network.