I have a network, which is not IPv6 routable and each device has self-assigned link-local addresses, but IPv6 connectivity does not operate and it is not configured (neither IP addresses, nor IPv6 DNS, nor routing). It is IPv4-only network. Recently I have noticed that at least one of Windows 7 hosts on a random basis obtains spontaneous IPv6 DNS server with link-local address (always the same), which does not answer nslookup queries. Moreover I have no idea where did it come from and I'm certain I didn't configure it by myself. Reconnecting gets rid of this DNS server for a while. Googling I found that it could be some device advertising itself or the like.
How come windows is setting IPv6 DNS on its own?
How do I identify the device, which is probably misconfigured, leading to this situation?