Some widespread IPv4 stacks refuse to handle these addresses,
so nobody would ever want to use them on the public IPv4 Internet.
And some widespread IPv4 stacks, refuse to handle IPv6 addresses.
it seems likely that more hosts currently support IPv6 than support use
of these IPv4 addresses. why should we go to more effort to gain a bit
more life out of IPv4 than it takes to transition to IPv6?
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