alt Hacker NewsMy former colleague Marco Davids from SIDN Labs (the R&D department at the .nl TLD operator) did an experiment in 2021 where he actively disabled IPv4 support on all components in his test network, even disabling the complete IPv4 stack in the FreeBSD kernel (not possible on Linux, at least not at the time). So far, his test is the only thing I know of that came close to an authentic simulation of an IPv6-only world.
https://www.sidnlabs.nl/en/news-and-blogs/can-we-do-without-...
AAAA record resolution is the real bottleneck for adoption. Once you have dual stack working, I did a real-world, simple test: Release your ISP IPv4 DHCP lease on the router (kill udhcpc) and flush DNS on your hosts. Now all public DNS lookups must resolve to a IPv6 domain. You will very quickly find many domains on the Internet still don't have AAAA records. Lots of popular services will simply fail to resolve their hard coded domains. QED.
https://whynoipv6.com/