Internet Addresses: An Uneven Shortage but an Inevitable One
USC Viterbi School of Engineering (02/01/11)

University of Southern California (USC) Viterbi School of Engineering researchers recently conducted an Internet census to monitor Web address usage. The researchers found that despite upcoming announcements from the Number Resource Organization and the Internet Assigned Numbers Authority stating that there are no more available Web addresses in the current IPv4 protocol, that is actually not the case.

The researchers found that although some allocated address blocks, which can hold has many as 16 million addresses, are heavily used, others are barely used at all. USC professor John Heidemann says that “probably only 14 percent of addresses are visible on the public Internet.” However, the researchers note that “as full allocation happens, there will be pressure to improve utilization and eventually trade underutilized areas.”

There were 2.8 billion available Internet addresses when researchers at USC’s Information Sciences Institute (ISI) conducted their first census in 2007. The latest census, conducted by Heidemann and ISI’s Aniruddh Rao and Xue Cui, found that 3.5 billion addresses are currently allocated out of a possible 4.3 billion. The researchers measured addresses in use by sending a message ping to each possible Internet address.

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So far my favorite comment on this problem has come from @gruber – He said (tweeted),  “When does the black market for IPv4 addresses start?”