I'm writing about this to spread the word. Many readers of this blog work at ISPs and hopefully many of them have IPv6 rolled out, or are in the process of doing so.
Technically here's what happens: Currently DNS lookups of www.google.com return A records (IPv4), and no AAAA records (IPv6). If you run an ISP that has rolled out IPv6, Google will add you (your DNS servers, actually) to a white-list used to control Google's DNS servers. After that, DNS queries of www.google.com will return both an A and AAAA record(s).
What's the catch? The catch is that they are enabling it on a per-ISP basis. So, you need to badger your ISP about this.
Why not just enable it for all ISPs? There are some OSs that have default configurations that get confused if they see an AAAA record yet don't have full IPv6 connectivity. In particular, if you have IPv6 enabled at your house, but your ISP doesn't support IPv6, there is a good chance that your computer isn't smart enough to know that having local IPv6 isn't the same as IPv6 connectivity all the way across the internet. Thus, it will send out requests over IPv6 which will stall as the packets get dropped by the first non-IPv6 router (your ISP).
Thus, it is safer to just send AAAA records if you are on an ISP that really supports IPv6. Eventually this kind of thing won't be needed, but for now it is a "better safe than sorry" measure. Hopefully if a few big sites do this then the internet will become "safe" for IPv6 and everyone else won't need to take such measures.
If none of this makes sense to you, don't worry. It is really more important that your ISP understands. Though, as a system administrator it is a good idea to get up to speed on the issues. I can recommend 2 great books:
- My friend Karl Siil recently released a book specifically on the topic of IPv6 transition issues for government enterprises, yet the on-line preview is brilliantly useful for enterprise and other sysadmins looking to get an introduction to the protocol, the history, and other issues: IPv6 Mandates: Choosing a Transition Strategy, Preparing Transition Plans, and Executing the Migration of a Network to IPv6, by Karl Siil. (Buy Online)
- The best practical sysadmin-oriented book on IPv6 is "IPv6 Network Administration", By Niall Richard Murphy, David Malone.(Buy Online)