The well of Internet Protocol (IP) addresses has run dry — for the most part.

In early February, the Internet Assigned Numbers Authority (IANA) doled out the last five blocks of IP addresses to regional Internet registries around the world, which are responsible for divvying up IP addresses among Iocal Internet service providers and other online stakeholders.

Experts project that the last batch of IP addresses will be exhausted by mid-year.

To clarify, there are still plenty of domain names (i.e. and URLs to go around. IP addresses are the 8-bit numerical labels that identify mobile devices (laptops, iPads, smart phones) within computer networks.

TECH NEWS: Are We Running Out of Internet Addresses?

IP addresses consist of four numbers between 0 and 255, separated by decimals. For example, your laptop’s IP address might be anything from to Those unique numerical labels allow computers and other devices to communicate among the vast network of servers that make up the Internet.

Why hasn’t more Y2K-style panic ensued? It isn’t that the Internet is running out of IP addresses altogether, but rather IP version 4 (IPv4) addresses.

Back in 1983, IANA designated around 4.3 billion IPv4 addresses, not predicting the incredible pace of tech development that would ensue. Due to the explosion of mobile devices in recent years and an ever-expanding wired population, those IPv4 addresses have been effectively gobbled up.


The IANA recognized this possibility early on, and in 1999, Internet Protocol version 6 (IPv6) was born. IPv6 addresses are 16-byte labels instead of 8-byte IPv4 labels, which means there are exponentially more to go around.

“I think IPv6 will easily get us 50 years, and could well get us much further,” said John Heidemann, a computer scientist at University of Southern California who mapped the global distribution of those 4 billion IP addresses.

Heidemann’s IP mapping also revealed that while the bulk of those IPv4 addresses have been handed out, a majority of them — roughly 85 percent — aren’t actually in use.

“This result suggests to me that we can probably do better in efficiently using the addresses we have,” Heidemann said. “In fact, if you look at the history of address allocation policies from ICANN (and the regional registries, we see their policies about (ensuring allocated IP addresses are utilized) before they give out more to IP addresses have gotten consistently stricter over the years.”


Those idle IP addresses explain why Microsoft was just able to purchase $7.5 million-worth of IPv4 addresses from Nortel Networks.

With trillions of IPv6 addresses waiting in the wings, it might sound like an easy fix, and some devices, including iPhones and Internet service providers have already made the transition to the 32-bit labels.

But a vast majority of the Internet has yet to upgrade its network equipment to recognize IPv6 addresses. As that transition occurs, there will certainly be hiccups along the way, although they’ll be more evident on the back end than for users.

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“I expect we will see disruptions for ISPs well before we see it for users,” Heidemann told Discovery News.  “By ‘disruptions’ here I mean much greater efforts required to support new users, and more difficulty diagnosing problems. Disruptions for end users will occur later.  My guess is the first will be higher costs for static IP addresses and multiple IP addresses, items needed mainly by businesses or certain kinds of professional users.”

Once the full crossover to IPv6 and its 340 undecillion (340 followed by 36 zeros) available addresses is completed, does that mean the Internet won’t run out of IP addresses ever again?

Heidemann doesn’t want to make that bet.

“One should be careful with ‘ever,’ since in 1985, the 4 billion IPv4 addresses looked quite huge,” he said.

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