In Pictures: Why the Internet needs IPv6

Explosive growth of Internet users, devices, apps creates demand for more IP addresses

What about allocated-but-unused IPv4 addresses?

A statistic touted by IPv6 naysayers is the amount of IPv4 address space that is allocated but unused, which is estimated at 1.2 billion IPv4 addresses by Addrex. These unused IPv4 addresses belong to U.S. government agencies, universities and companies involved in the original network research that led to the Internet. Companies like Addrex facilitate the sale of unused IPv4 addresses to service providers to extend the life of IPv4. Here is a list of lucky U.S. organizations with /8 blocks of IPv4 addresses, which have 16.7 million IPv4 addresses each and are worth $500 million or more on the resale market, Addrex says:- General Electric, MIT, IBM, MERIT Network (Michigan universities), Xerox, Prudential Insurance Co., Eli Lilly & Co., Halliburton Co., Ford Motor Co., DuPont

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