6TO4 Windows 2003 DNS

Question

This is puzzling me a bit.

We are running server 2003 DNS/DHCP and normally we disable IPV6 on the client end. But I have just noticed with windows 7 and server 2008 R2 if I disable IPv6 then it registers an 6TO4 address in DNS not its Standard IP address.

If I enable IPv6 it registers its IP.

Can anyone explain why this is?

Answer 1

In Windows 6.x (including Vista, Server 2008, Server 2008 R2, and Windows 7), unchecking IPv6 under Local Area Connection properties is not enough to disable IPv6 completely.

If you want no IPv6 at all on a Windows 6.x machine, you need to modify the registry:

Under HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip6\Parameters\ set DisabledComponents to 0xffffffff (hex).

Reference: http://support.microsoft.com/kb/929852

Of course, this could be done via GPO/administrative template if desired.

Answer 2

Yes, 6to4 is a IPv4 to IPv6 transition feature which IPv4 clients can count on to talk to each other with IPv6 protocol. Since you don't need the IPv6 (nor IPv6 transition), you may check how it works if you disable the 6to4 Adapter.

1. Click Start – Run – Type devmgmt.msc ­and click OK – in Device Manager, click View and select Show hidden devices – expend Network Adapters – check the status of 6TO4 adapter.

2. Disable 6TO4 adapter in Device Manager.