What is loopback address?
A loopback address is a type of IP address that is used for testing the communication or transport medium on a local network card and / or for testing network applications. Data packets sent over a loopback address are routed back to the original node without change or change.
A loopback address is mainly used to verify that the locally connected physical network card is working properly and that the TCP / IP stack is installed.
Typically, a data packet sent over a loopback address never leaves the host system and is sent back to the source application. When testing network / IP-based applications, it is implemented on a virtual network card, which is a complement to the physical network card. This allows users to test an application with an instance of the server and client on the same machine, with the ability to transfer network data between, even without access to a physical network.
In IPv4, the most common loopback address is 127.0.0.1, but it can be expanded to 127.255.255.255.