Specific PCs "infecting" networks they join with IPv6 (causing disruption of software)

I have a set of PCs which if connected to a windows network will make all computers on that network default to ipv6 when resolving names. This happens even if IPv6 is unchecked, if the ipv4 binding is set above 6 in the advanced properties of the network card. If any of these PCs joins a network with a point of sale system (Aloha) that system develops problems since Aloha does not like IPv6. At all. All computers including the aloha terms are Windows 7, 32 or 64 bit.

Reproduced this with different routers and network topologies.

For example, I take one of these particular PCs to my home network. Prior to the terminal going onto the network
ping localhost -->
ping computername --> 192.x.x.x

After the PC has joined the network, just attached to the same router, not on the same workgroup, etc., now all computers on the network return

ping localhost --> ::1
ping computername --> 08fe:xxxx (IPv6 address)
ping computername -4 --> 192.x.x.x
ping localhost -4 --> 192.x.x.x

This behavior continues even without IPv6 enabled on any adapter on the network. When the PC is removed from the network, all other PCs continue with the new behavior.

I have tried netsh winsock reset, net stop dnscache, netsh int ip reset.log hit, unchecking IPv6 in multiple places, ensuring binding order has IPv4 above IPv6 on all network adapters (none hidden) etc. It's like this PC infects other windows PCs with IPv6 ...

I have not tried disabling IPv6 from the registry or by Policy in my lab but I believe I tried this on previous network with no effect. Any thoughts appreciated

Issue solved! See MS KB How to disable IP version 6 (IPv6) or its specific components in Windows 7, in Windows Vista, in Windows Server 2008 R2, and in Windows Server 2008

Specifically, if the HKLM\system\currentcontrolset\services\tcpv6\parameters\disabledcomponents is not set to DWORD 0xFFFFFFFF then this behavior can occur.

The above key is from memory, see the MS KB for detailed information

This website is not affiliated, owned, or endorsed by Microsoft Corporation. It is a member of the Microsoft Partner Program.