I wanted to make a clarification on one of the things I said about IPv6 on my blog.  I was contacted buy a fantastic person a corporate you wanted to make sure we get the correct information out!  :-) The questions from the webcast was:

Question: In IPv4 and IPv6 mixed environments is the protocol being used determined by the application programming or the operating system?
Answer: Determined by the application

As I have learned this is not a fully complete or fair answer.  On Vista, if you turn off IPv4, all of the apps will try to use IPv6 whether they are written for v6 or not.  It is true that some applications are hardcoded for v4 (or v6) but that is bad programming – we tell coders to write their applications to be ‘IP Agnostic’ so that the app just throws data at the stack, and the stack determines which address to use.  This is the better way of handling things, and prevents these migration issues from arising in the future if we ever migrate to another new IP version.  So truthfully, the OS *does*  (Windows Vista) determine whether to use v4 or v6, unless the app is hardcoded for v4.

I also learned that I was mis-pronouncing Teredo, proper guide to pronunciation is below.  :-) 

Teredo:  Pronounced (Ter-AY-do) not (Ter-EE-do)

Also as a FYI, Teredo isn’t on XP SP1 or 2 until you install the advanced networking pack.

So a huge thanks to Sean up at corporate to clarify that for me!  Thanks Sean!

For the Full Q/A take a look here: Why Deploy Internet Protocol Version 6 (IPv6): Webcast (02-19-2007)