Are we running out of Internet addresses?


Is the Internet really running out of IP addresses and if so, what does it mean to me?

- Mike


This question was answered on January 26, 2011. Much of the information contained herein may have changed since posting.

Underneath the surface of what we type into our web browsers to get to a website is a structured numbering system that is the actual address of each website that we want to go to This numbering system is referred to as the Internet Protocol (IP) address.

For instance, when you type to get to our website, your browser asks a DNS (Domain Name System) server to translate the ‘easy to remember for humans’ address into the actual numeric IP address which is (if you type that in your browser, it will take you to our website as well).

In addition to every website needing unique addresses, so too do the devices that allow us to connect to those websites: cable modems, DSL routers, business networks, mobile devices, etc.

When the founders of the Internet created this addressing scheme, the ARPAnet was considered a short-term government experiment, so the roughly 4 .3 billion address limitation was considered exponentially more than would ever be needed.

“The only problem is the experiment never ended” says Vint Cerf widely considered the ‘father of the Internet’ as the program manager of the ARPAnet (Advanced Research Projects Agency Network).

To be clear, every device that can connect to the Internet does not require a unique IP address as most of our devices connect via some form of network (home network, coffee shop, business network, etc.)

For instance, if you have a cable modem and a wireless router to allow you to share the connection, your cable modem is assigned a single ‘public IP address’ which is unique (and from the pool that is running low), but all the computers behind your router use ‘private IP’ addresses, so it doesn’t matter how many computers, laptops, tablets, webcams or gaming consoles you use to connect to the Internet, you are still only using one public IP address.

The organization that oversees the assignment of IP addresses, ICANN (Internet Corporation for Assigned Names and Numbers) is getting close to the end of the available addresses (most are estimating Feb of 2011), but since they assign large blocks of addresses to Internet Service Providers and other large Internet entities, we aren’t in danger of running out of individual IP addresses any time soon.

It is, however, just a matter of time before we do run out of IPv4 addresses, so the industry has been working on a solution known as IPv6 which uses a much more robust addressing scheme that allows for 340,282,366,920,938,463,463,374,607,431,768,211,456 unique addresses instead of the paltry 4.3 billion available via IPv4.

This problem has been on the horizon for over a decade (the IPv6 standard was published in 1998) and the industry has been slowly preparing for the eventual shift For the foreseeable future, both IPv4 and IPv6 will be in use across the Internet as there is not a feasible way (or need) to convert everything on the Internet overnight.

Most everything you use as a consumer is likely already capable of resolving IPv6 addresses or can be configured to do so Microsoft, for instance, started incorporating the protocol as far back as Windows XP and most current residential routers have provisions for dealing with both protocols.

The bottom line is that you have nothing to worry about any time soon as long as you keep your devices, operating systems & browsers updated (the people that provide you Internet service and that host websites are the ones that have a lot of work to do).

Even if you have ancient equipment that can’t resolve IPv6 addresses, you won’t have a problem getting to anything that you can access today; it would simply impede you from accessing IPv6 only sites, which won’t be common for many years (major sites will operate as dual sites for a long time or risk losing traffic).

The first real global test coined ‘World IPv6 Day’ is scheduled for June 8th, 2011 and will mark the first day that a large consortium of websites and Internet service providers will perform a 24-hour large scale test.

For those that are curious and would like to test their IPv6 connectivity, you can visit and also learn a lot more about World IPv6 Day.

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Posted by Ken of Data Doctors on January 26, 2011