I've also just been bitten by this. A couple of freshly installed Debian 8.5 boxes with using just standard DHCP for their network settings are having their DHCP-provide resolv.conf overwritten by rdnssd. IPv4 nameservers, search paths, domain, everything.
Running dhclient brings it back, of course, but at some point this rdnssd wipes it again. This is pretty much a stock out-of-the-box installation without any network tweaks or even any particular thought about the network. Is this a bug that's only triggered by network local IPv6 config? It certainly seems pretty bad that a clean installation seems to suffer from this hard to track down problem. bjb
