The American Registry for Internet Numbers (ARIN) has put in place new rules that allow companies to forecast their address needs for only three months at a time instead of the previous one year period.

Microsoft's plans to purchase Nortel's entire block of IPv4 address in this environment has .

Some posters on the group's mailing list speculated that Microsoft was buying the addresses in order to resell them at a later date. "They can only get them for free from ARIN if they can document an immediate demand," one poster on NANOG noted.

"Perhaps they don't have an immediate demand, and are simply stockpiling addresses for later use post ARIN depletion? Or perhaps they hope to make a profit then by selling them to someone else," the poster noted.

Others wondered how Microsoft could purchase the address block when ARIN polices required that the blocks be returned by Nortel to a common pool where others could use it. One poster noted that the "recipient organization has to show justified need," in order to get the blocks.