IPv6 Connectivity Issue - Cannot connect to IPv6 sites intermittently

Question

I've configured an ISATAP router to enable me to connect to IPv6 sites. The interesting thing is that it sometimes works and sometimes does not and I do not know where the problem lies. Can anybody help me fix this connectivity issue?

As a start I'm pasting what I think might be helpful here.

Using netsh it shows something like this:

Router Name            : isatap.sjtu.edu.cn
Use Relay              : default
Resolution Interval    : default
netsh interface ipv6 isatap>

Ping isatap.sjtu.edu.cn shows:

Pinging isatap.sjtu.edu.cn [202.112.26.246] with 32 bytes of data:
Reply from 202.112.26.246: bytes=32 time=74ms TTL=44
Reply from 202.112.26.246: bytes=32 time=74ms TTL=44
Reply from 202.112.26.246: bytes=32 time=74ms TTL=44
Reply from 202.112.26.246: bytes=32 time=74ms TTL=44

IPConfig output:

Windows IP Configuration


Ethernet adapter Local Area Connection:

   Connection-specific DNS Suffix  . : resnet.ust.hk
   IPv6 Address. . . . . . . . . . . : 2002:8f59:a0c7:b:98b5:560d:8ec7:ec11
   Site-local IPv6 Address . . . . . : fec0::b:98b5:560d:8ec7:ec11%1
   Temporary IPv6 Address. . . . . . : 2002:8f59:a0c7:b:5d27:6f33:cbb3:fec9
   Link-local IPv6 Address . . . . . : fe80::98b5:560d:8ec7:ec11%11
   IPv4 Address. . . . . . . . . . . : 143.89.160.16
   Subnet Mask . . . . . . . . . . . : 255.255.252.0
   Default Gateway . . . . . . . . . : 143.89.163.254

Tunnel adapter isatap.resnet.ust.hk:

   Media State . . . . . . . . . . . : Media disconnected
   Connection-specific DNS Suffix  . : 

Tunnel adapter Local Area Connection* 12:

   Media State . . . . . . . . . . . : Media disconnected
   Connection-specific DNS Suffix  . : 

Ping ipv6.google.com:

Ping request could not find host ipv6.google.com. Please check the name and try again.

Answer 1

I don't see any mention of IPv6 DNS. Your pings are being sent over IPv4.

To ping the IPv6 way:

ping -6 www.kame.net