Loopback address definition

A loopback address is an IP address you can use to loop and return data packets through a network interface card. The loopback address starts with the following numbers: 127.0.0.1. If you send data packets to a loopback address, they won’t reach the address. Instead, they will get looped through your network interface card and returned back to where you sent them from. You can use a loopback address to test your communication channels without modifying or processing the data you send. Most businesses use it to check their internal paths. 127.0.0.1 is the most common loopback address used in IPv4, but there are also other loopback addresses you can use, going up to 127.255.255.255.

See also: ping, IPv4

Loopback address benefits

• Can be used to identify the devices that live on your network.
• Can be used for testing internal paths and communication channels.
• Can be used for troubleshooting.
• The loopback address is always online and available for usage.
• It never changes.
• You can change your loopback address if you need to.
• Protocols like OSPF require a loopback address to function.
• It enables commands like ping Mpls to function properly.
• Stateless firewall rules can be applied to the loopback address.

Further reading