On: Thinking about our passive exposure to IPv6 issues

[znpy]

To add a trivial example: if an application is coded well, it’s ready to connect to hosts both on ipv4 and ipv6, in the sense that when resolving a dns name, it will ask for addresses of any kind (unless it supports being explicitly told to only use ipv4).

So now you’re getting a record with multiple ip addresses, some of which are ipv6, but ipv6 is blocked… there you go with random connection delays and possibly timeouts.

Ipv6 exists and it’s getting more and more adoption, no matter if some people keep their head under the sand…

[kps → znpy]

> multiple ip addresses, some of which are ipv6, but ipv6 is blocked… there you go with random connection delays and possibly timeouts.

RFC6555 “Happy Eyeballs” discusses this.

[xemdetia → znpy]

A/AAAA records are a special sort of hell to debug remotely. "My browser can find it but I can't ping it! What do you mean ping6?"

In some environments that is maddening and I don't blame people for just deciding not to either at all or only translating at WAN.