No IPv6 by design to increase reliability...

Thu Jan 17 19:52:34 UTC 2019

Broken IPv6 connectivity happens all the time, sometimes for weeks, 
before some folks seem to notice. I could understand why one could take 
the stance that IPv4 only is less problematic (and therefore more 
available) than dual stack. Overall, it might depend on your application 
and the happy eyeballs tech built (or not built) into it.

John Von Essen wrote on 1/17/2019 1:45 PM:
> 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
>
>
>