Comment 57 for bug 24828

The Vista DNS Query Behaviour is described here:

http://www.microsoft.com/technet/network/ipv6/vista_dns.mspx

"- If the host has only link-local or Teredo IPv6 addresses assigned, the DNS Client service sends a single query for A records.
- If the host has at least one IPv6 address assigned that is not a link-local or Teredo address, the DNS Client service sends a DNS query for A records and then a separate DNS query to the same DNS server for AAAA records. If an A record query times out or has an error (other than name not found), the corresponding AAAA record query is not sent."

I don't know why they don't do any AAAA query if you have a teredo address (which is globally routable), but the rest sounds reasonable.