With the recent Microsoft announcement that IPv6 will soon be supported in Azure Active Directory, I thought it might be useful to write a brief explainer on what IPv6 is and why it’s (slowly) being adopted.

IPv6 (Internet Protocol version 6) is the latest version of the Internet Protocol (IP) that is used to identify devices on a network and route traffic between them. It was developed to address the shortage of available IP addresses that were becoming an issue with the previous version of IP, IPv4.

One of the main differences between IPv4 and IPv6 is the number of available IP addresses. IPv4 uses 32-bit addresses, which allows for a maximum of 4.3 billion unique addresses. IPv6, on the other hand, uses 128-bit addresses, which allows for a much larger number of unique addresses - approximately 340 trillion, trillion, trillion. This means that IPv6 addresses the problem of IP address depletion that we were facing with IPv4.

Another difference between IPv4 and IPv6 is the format of the IP addresses. IPv4 addresses are represented by four numbers separated by periods (e.g. 192.168.1.1), whereas IPv6 addresses are represented by eight groups of four hexadecimal digits separated by colons (e.g. 2001:0db8:85a3:0000:0000:8a2e:0370:7334)

IPv6 also includes several new features that are not present in IPv4, such as:

• A simplified header format that allows for more efficient routing of traffic

• Improved support for mobility, allowing devices to change their IP address while remaining connected to the network

• Built-in support for security features such as IPsec

IPv6 is not just an upgrade of IPv4, it is a new internet protocol, that is why it is not backward compatible with IPv4. IPv6 is gradually being adopted around the world, and many Internet Service Providers (ISPs) now offer IPv6 connectivity to their customers. As the IPv4 address space continues to be depleted, it is likely that IPv6 will become increasingly important in the years to come.