Datum: 01.02.2011 22:26
Early adopters using some tunnel (6to4, sixxs, ...) usually prefer to use IPv4 (available native) over IPv6 (tunneled through somewhere not too near).
Furthermore, some applications don't even try IPv4 once IPv6 is or seems available locally.
Here are some hints on how to invite or force applications resp. operatings systems to prefer IPv4:
precedence ::ffff:0:0/96 100.
/sbin/sysctl net.ipv6.bindv6only=0respectively editing