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