What is IPv4 and IPv6 ?

There are two versions of Internet Protocol in popular use: version 4 (IPv4) and version 6 (IPv6).

  • IPv4 was developed in the early 1980s. It has capacity of just over four billion IP addresses, almost all of which have now been allocated to Internet service providers and users. An IPv4 address looks like this:
  • IPv6 is the next generation of IP, with a 128-bit address space, providing 340 undecillion addresses. An IPv6 address looks like this: 2001:0db8::53.

While the intention is for IPv6 to surpass IPv4 as the commonly used system, this process is ongoing. Adoption is important because IPv4 and IPv6 essentially operate as parallel systems, meaning data cannot be exchanged between these protocols without transition technologies.