> And yet, AWS itself doesn't natively support IPv6

Public ELBs support it. And even if you're only using one instance behind the ELB, its $14/month for that ELB. No one needs IPv6 on backend instances if they're only talking to the outside world through ELBs.

EDIT: I'm wrong.

> Load balancers in a VPC support IPv4 addresses only.

http://docs.aws.amazon.com/ElasticLoadBalancing/latest/Devel...

Only in Ec2 classic which isn't available to most AWS users. VPCs don't have it. So in practice AWS has almost zero IPv6 support.

Thanks for pointing out my mistake! I've corrected my comment.

Big if. ELBs are entirely optional. Using them just to be ipv6-compatible is a hack.

Are you serving production traffic with a single instance?

Yes, actually. We're using lambdas for all the heavy lifting, so we don't need much at all for the app server.

AWS is also used by plenty of smaller players who won't ever need more than one instance for everything. Or just devs who want a remote server to play with. Not everyone needs ELBs.

I am surprised, given the age of AWS, that they didn't go completely V6 internally from the get go.

There were no vendors providing enterprise grade IPv6 routers and switches when they started.

I seem to remember even Cisco doing IPv6 by 2006?

Not at an enterprise level. The support was experimental.

Without going into tremendous detail, this is roughly how:

https://developer.apple.com/library/ios/documentation/Networ...

> I'm curious, how does Apple detect apps which don't support IPv6?

If their network is entirely IPv6 then they may not do anything special to test it. If an app fails with IPv4/IPv6 related errors then it doesn't support IPv6 properly.

And mind you, this means that your app needs to support IPv6 addressing. Your backend server doesn't need to support IPv6, since you can route to IPv4 addresses on IPv6-only networks.

If you're using the correct APIs with IPv4 addresses, you're fine.

In the App Review, they test the app on a IPv6 only network, if they have any network-related error, the app will be rejected.

source?

The (new?) Review Guidelines https://developer.apple.com/app-store/review/guidelines/#sof... punto 2.5.5

"We will be reviewing on an IPv6 network, so if your app isn’t compatible with the IPv6 addressing, it may fail during review".

really easy to google up a source, e.g.: https://developer.apple.com/news/?id=08282015a

> At WWDC 2015 we announced that iOS 9 will support IPv6-only network services. All apps submitted to the App Store must support IPv6 starting in early 2016.