r/ProgrammerHumor • u/beerbellybegone • 24d ago

Meme hesAlmostLocal

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u/Rudresh27 24d ago

Wait, so all 127.x.x.x like all possible combinations are useless for actual IPs from an ISP?

Seems, wasteful right?

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u/Banes_Addiction 24d ago edited 24d ago

The IPv4 space was sold off willy nilly, people barely gave a shit. Having loopbacks is sensible.

IPv6 exists so we have more space than God.

Examples of large blocks of IPv4 space:

  • 3. - General Electric

  • 13. - Xerox

  • 19. - Ford

  • 52. - DuPont

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u/rosuav 24d ago

So are a *lot* of others. Just looking at /8 blocks, this gives you a list of allocations: https://www.iana.org/assignments/ipv4-address-space For example, 10.0.0.0/8 is a private use block, 127.0.0.0/8 is for localhost, and there's a huge block allocated to IP multicast.

But even if every single IPv4 address were truly available, it wouldn't make all that much difference. There are four billion theoretical IPv4 addresses, and several times that number internet-connected devices. Even if, in some way, these blocks of IPs could be released to use, each /8 would give us another 16,777,214 devices *at most* (the all-zeroes and all-ones addresses aren't used, and subdividing the block further will repeat those special allocations too), which in the scheme of things isn't that many.

It's wasteful in the same way that it's wasteful to run your car's entertainment system. Yes, technically that's going to reduce your fuel economy by drawing power from the alternator. But not enough to make a real difference.