network

Surfing the Vast Ocean of IP Address Ranges

by Sam — a year ago

This article is also available in french

Reserved IP Addresses: A Technical Overview

The Internet is a global network connecting billions of devices, each requiring a unique address for effective communication. These unique addresses are called IP (Internet Protocol) addresses. However, not all IP addresses are created equal. Some are reserved for specific uses and are not publicly allocable. Understanding why these addresses are reserved and how they have evolved over time is crucial to understanding how the Internet works.

Why Reserved Addresses?

Reserved IP addresses play a critical role in how the Internet functions. They are used for specific network communications, for testing, for documentation, and for other specific uses. For example, the IP address 127.0.0.1 is always reserved for loopback communication, allowing a host to communicate with itself.

Private IP Address Ranges

Private IP addresses are those that are reserved for internal use behind a router or other Network Address Translation (NAT) device, apart from the public. These addresses are in contrast to public IP addresses, which are public and can't be used within a home or business network. Here are the ranges of private IP addresses:

Class A : 10.0.0.0 to 10.255.255.255
Class B : 172.16.0.0 to 172.31.255.255
Class C : 192.168.0.0 to 192.168.255.255

These private IP addresses allow an entirely separate set of addresses that allow access on a network but without taking up a public IP address space.

Reserved Address Ranges

Here are some IP address ranges reserved for specific uses and are not publicly routable on the Internet:

0.0.0.0/8: Used for current networks.
127.0.0.0/8: Reserved for loopback communications.
169.254.0.0/16: Used for Automatic Private IP Addressing (APIPA).
192.0.0.0/24: Reserved for the IANA IPv4 Special Purpose Address Registry.
192.0.2.0/24, 198.51.100.0/24, 203.0.113.0/24: Reserved for documentation and examples.
224.0.0.0/4: Used for multicast.
240.0.0.0/4: Reserved for future use.
255.255.255.255/32: Used for limited broadcasts.

Evolution Over Time

With the evolution of the Internet and the increase in connected devices, IP address management has had to adapt. For example, the transition from IPv4 to IPv6 significantly changed the role of non-routable IP addresses. Each device using IPv6 has a unique and routable address, offering an almost infinite number of unique addresses.

References

For more information on reserved IP addresses and their use, you can check out the following resources:

These resources can help you understand reserved IP addresses and their use in more detail. Remember that standards and practices can evolve over time, so it's important to regularly check reliable sources to stay up-to-date.