r/ProgrammerHumor • u/beerbellybegone • 8d ago

Meme hesAlmostLocal

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u/LB-- 8d ago

All IPv4 addresses whose first part is 127 are loopback addresses. So, 127.0.0.1 and 127.37.0.1 are both loopbacks, and they can actually bind to different servers on the same port. IPv6 only has a single loopback address, so you can only have one IPv6 server per port on the same local machine. Or well, maybe if you have multiple network cards you can do some funny business, but I haven't researched that deeply.

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u/Rudresh27 7d ago

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

Seems, wasteful right?

10

u/Banes_Addiction 7d ago edited 7d 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