What is loopback IP address

What is loopback IP address

The loopback IP address is the address used to access itself. The IPv4 designated 127.0.0.1 as the loopback address with the 255.0.0.0 subnet mask. A loopback interface is also known as a virtual IP, which does not associate with hardware interface. On Linux systems, the loopback interface is commonly called lo or lo0. The corresponding hostname for this interface is called localhost.

The loopback address is used to test network software without physically installing a Network Interface Card (NIC), and without having to physically connect the machine to a TCP/IP network. A good example of this is to access the web server running on itself by using http://127.0.0.1 or http://localhost.

Definition - What does Loopback Address mean

A loopback address is a type of IP address that is used to test the communication or transportation medium on a local network card and/or for testing network applications. Data packets sent on a loopback address are re-routed back to the orginating node without any alteration or modification.

Techopedia explains Loopback Address

A loopback address is primarily used as a means to validate that the locally connected physical network card is working properly and the TCP/IP stack installed. Typically, a data packet sent on 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 interface card, which acts an addition to the physical network card. This enables users to test an application with an instance of server and client on the same machine, with the ability to transmit network data between, even without access to a physical network.
In IPv4, 127.0.0.1 is the most commonly used loopback address, however, this can range be extended to 127.255.255.255