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That can't be totally true, Twitter doesn't work on v6.
by bifrost 7y ago
That can't be totally true, Twitter doesn't work on v6.
- WorldMaker 7y agoApps can't request IPv4 addresses directly (ie, no hardcoded IPv4 addresses allowed), but DNS may still return them for indirect use (via the Happy Eyeballs [1] approach that heavily favors IPv6 because an increasing number of mobile carriers are IPv6-only or IPv6-primarily and IPv4 addresses must get sent to NAT64 gateways). [1] https://en.wikipedia.org/wiki/Happy_Eyeballs https://en.wikipedia.org/wiki/Happy_Eyeballs
- rstuart4133 7y agoNot only can it be true I've done it at a conference, which is to say I've implemented an IPv6 only network for conference delegates and had zero connectivity complaints. The ingredient you are missing is while the clients only talk IPv6, the gateway they go through (must) have both IPv6 and IPv4 addresses. There is a well defined mapping from IPv4 to IPv6 addresses, so if the IPv6 clients need to communicate with a IPv4 only host they use it's mapped IPv6 address. The gateway then NAT's all those mapped IPv6 addresses to it's IPv4 address. Which only leave the problem of does an IPv6 client know to use an mapped IPv4 address, given it is supposed to know nothing about the IPv4 world. The answer is you make it use a DNS server that lies. I'll leave it to you to figure out exactly how it lies, but it isn't hard to figure out given it has clients that only understand AAAA records, and some hosts (such as twitter) that only resolve to A records.
- bifrost 7y ago> The gateway then NAT's all those mapped IPv6 addresses to it's IPv4 address. Right, then its not a pure v6 network, its got v4 somewhere patched in. When I'm on my pure v6 network at home, Twitter does not work.