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Comment by tomxor | Hacker News Reader

> IPv6 adoption is at like 45% globally [...] https://www.google.com/intl/en/ipv6/statistics.html

> link -> The graph shows the percentage of users that access Google over IPv6

How does this work in practice, does user equipment end up with dual IPv4 IPv6? if not how do they access IPv4 only sites (of which there are still plenty)?

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It's just as you have described, this is called dual stacking and is currently the most common type of IPv6 deployment.

Alternatively, cellular ISPs may make use of NAT64+DNS64. In this case, the IPv4 addresses are combined with a NAT64 prefix (most likely 64:ff9b::/96), producing addresses such as `64:ff9b::198.51.100.1`. It is effectively the same as CGNAT, but pretty much everything is single stacked IPv6 up to the IPv4<->IPv6 border relay in the ISP network.

The way it's supposed to work is the ISP delegates a prefix to the user's router, the router will advertise for that subnet and client devices will use slaac to configure their ipv6 addresses. Meanwhile for IPv4 it operates as normal. For incumbent, mostly wired, Western ISPs that means a pool of IPv4 addresses and subscriber level NAT. For everyone else, that probably means CGNAT.

My ISP gives me both an IPv4 address and a heap of IPv6, most browsers will use what is called Happy Eyeballs to try both IPv4 and IPv6 at the same time and use the one that connects the fastest.

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