"There are still known issues with DNS records, and if you have a AAAA record and an A record, what happens to your application?" Winters said. "You go to the AAAA and if it's not there, your application will hang." AAAA is the IPv6 record type in DNS, while the A record is for IPv4. Winters noted that it is surprising how some applications will only take the top record from a DNS resolver, whatever that record may be. He added that there is an IETF draft called, Happy Eyeballs which attempts to help resolve that issue.
darthcamaro writes: We've all been hearing for years that we should start looking at IPv6 — and now that IPv4 that seems really obvious, but there is a catch..IPv6 isn't quite ready to be deployed at scale. There are a long list of interoperability issues including problems with DHCPv6, IPv4 to IPv6 transition system mechanisms and oh yeah, web applications too.