I think you’ve got it basically right. Over time, the number of v6 only clients will continue to grow. (It’s infinitessimally small right now) It should, however, also be noted that there are a larger and growing number of v6 capable clients with increasingly degraded v4 capabilities (v6 only handsets with nat64 or 464xlat, cgn, etc.) which are also negatively impacted by the decision not to support v6 in the scenario described.
If v6 were such a problem as described, I think it wouldn’t be so readily embraced by facebook, google, Comcast, Netflix, etc. Owen > On Jan 17, 2019, at 11:45, John Von Essen <j...@essenz.com> wrote: > > I was having a debate with someone on this. Take a critical web site, say one > where you want 100% global uptime, no potential issues with end users having > connectivity or routing issues getting to your IP. Would it be advantageous > to purposely not support a AAAA record in DNS and disable IPv6, only exist on > IPv4? > > My argument against this was "Broken IPv6 Connectivity" doesn't really occur > anymore, also, almost all browsers and OS IP stacks implement Happy Eyeballs > algorithm where both v4 and v6 are attempted, so if v6 dies it will try v4. I > would also argue that lack of IPv6 technically makes the site unreachable > from native IPv6 clients, and in the event of an IPv4 outage, connectivity > might still remain on IPv6 if the site had an IPv6 address (I've experienced > scenarios with a bad IPv4 BGP session, but the IPv6 session remained up and > transiting traffic...) > > Thoughts? > > > -John > >
