Network - Loopback IP address (virtual IP, lo or lo0')

About

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.

Usage

The loopback address is used to test network software:

Example

A good example of this is to access the web server running on itself by using http://127.0.0.1 or http://localhost.

A loopback adapter is required then if:

  • You are installing on a DHCP computer, or
  • You are installing on a non-networked computer and plan to connect the computer to a network after installation.

Dhcp

Dynamic Host Configuration Protocol (DHCP) assigns dynamic IP addresses on a network. Dynamic addressing allows a computer to have a different IP address each time it connects to the network. In some cases, the IP address can change while the computer is still connected. You can have a mixture of static and dynamic IP addressing in a DHCP system.

In a DHCP setup, the software tracks IP addresses, which simplifies network administration. This lets you add a new computer to the network without having to manually assign that computer a unique IP address. However, before installing an application onto a computer that uses the DHCP protocol, you need to install a loopback adapter to assign a local IP address to that computer.

Documentation / Reference


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