I have a puzzling situation with IPv6 on my Windows 7 clients. If I use automatic allocation of IPv6 addresses on a client, it appears to be happy, but will always use IPv4 from then on. If I try to force it to use IPv6 (by adding the -6 option on ping, for example), it just complains 'Ping request could not find host xxxxxx. Please check the name and try again.' But if I allocate a static IPv6 at a client everything works fine. It doesn't matter what I do at the server. I currently have an IPv4 scope and just minimal IPv6 DHCP server options (but no actual IPv6 scope). I have also tried creating an IPv6 scope with no apparent effect on the problem. I have also played with ISATAP (not really relevant as far as I understand it, but thought it might have an effect) but again, nothing changes. Also, when manually configuring a client I don't need to provide a default gateway or DNS server address. It just works if I put in a static IPv6 address. Pinging ::1 on a client always works. Any thoughts gratefully received. Regards, WilliamRegards, William

1. Pinging on loopback address ::1 is simple test of IPv6 stack and does not give any information on the external problem on network. 2. What DHCP server do you use and how is the server configured? The same question is for DNS. 3. Use release and renew parameters whenever you do any change in configuration of DHCP and flushdns when changing configuration od DNS. 4. When ever you solve or ask a question concerning TCP/IP setting, work with output from ipconfig /all 5. If you have difficulties with discovering the processes behind, use network monitor to pinpoint failing component. Regards Milos

The DHCP and DNS servers are both the standard offerings on Windows 2008 R2 (I only have one server, so its a DC). Like I mentioned earlier, it doesn't seem to matter what I do at the server, changing a client to use a static IPv6 address makes it work, using the dynamic setting causes it to fail. At the moment, I have a DHCP IPv6 zone using prefix fdcb:477d:5ade::. I can see the issued leases in DHCP and they are also turning up in the DNS forward and reverse zones. So that is all working as expected (at least as I expect, which may be a different thing). However, if I try to ping a client with a DHCP-allocated IPv6 address at the server, I just get 'Request timed out' unless I force it to use its IPv4 address. On the client side, the DHCP-allocated IPv6 address is shown by ipconfig /all, along with the correct IPv6 DNS server address. However, pinging the server either falls back to IPv4, or if I insist on IPv6, it fails with 'Ping request could not find host apollo. Please check the name and try again'. In fact, with a dynamically-allocated IPv6 address, nslookup on a client fails until I tell it to use the server's IPv4 address. So, if I use a static IPv6 address on a client, everything is fine. If I use a dynamic IPv6 address, it breaks. (BTW, the clients are all mostly configured to use dynamically-allocated IPv4 addresses from the same server.) Regards, William

I believe I've found the source of the problem, but don't know how to solve it. If I enter a static IPv6 address on a Windows 7 client, the IPv6 routing table looks like this: IPv6 Route Table =========================================================================== Active Routes: If Metric Network Destination Gateway 10 266 ::/0 fdcb:477d:5ade::1 1 306 ::1/128 On-link 10 266 fdcb:477d:5ade::/64 On-link 10 266 fdcb:477d:5ade::1:30/128 On-link 10 266 fdcb:477d:5ade:0:e8d2:3e9e:e555:2120/128 On-link 10 266 fe80::/64 On-link 10 266 fe80::550a:c2c7:65f4:1814/128 On-link 1 306 ff00::/8 On-link 10 266 ff00::/8 On-link =========================================================================== Persistent Routes: If Metric Network Destination Gateway 0 4294967295 ::/0 fdcb:477d:5ade::1 =========================================================================== BUT if I set the client to use a dynamic IPv6 address, the first entry in each part of the table above disappear: IPv6 Route Table =========================================================================== Active Routes: If Metric Network Destination Gateway 1 306 ::1/128 On-link 10 266 fdcb:477d:5ade:0:e8d2:3e9e:e555:2120/128 On-link 10 266 fe80::/64 On-link 10 266 fe80::550a:c2c7:65f4:1814/128 On-link 1 306 ff00::/8 On-link 10 266 ff00::/8 On-link =========================================================================== Persistent Routes: None So basically, there is no default gateway. Where is the default gateway info supposed to come from when the Windows 7 clients are using dynamic IPv6 addresses? Regards, William

Got this working now. I did a few things on the server but I'm not sure which are absolutely essential: netsh int isa set state disabled {disables the isatap tunnelling interface } netsh int tol set state disabled {disables the teredo tunnelling interface } netsh int ipv6 add route ::0/0 <server_interface> store=persistent publish=yes I also did a policy update (gpupdate /force). At present we cannot use IPv6 with the Internet so this just allows IPv6 to work internally.Regards, William

Got this working now. I did a few things on the server but I'm not sure which are absolutely essential: netsh int isa set state disabled {disables the isatap tunnelling interface } netsh int tol set state disabled {disables the teredo tunnelling interface } netsh int ipv6 add route ::0/0 <server_interface> store=persistent publish=yes I also did a policy update (gpupdate /force). At present we cannot use IPv6 with the Internet so this just allows IPv6 to work internally.Regards, William

Hi, I am glad to hear that the issue has been solved. Hope your experience will help other community members facing similar problems. Regards Vincent Wang TechNet Community Support