At my University (which does not currently provide or support any kind of IPv6) I am currently wrestling with an issue where a host on the university network is advertising IPv6 routes and prefixes (using a 6to4 prefix..) and then null routing them (IE, dropping the packets silently instead of returning destination hot unreachable.) This is a problem. I cannot reach sixxs or any host with an AAAA addresses, because both Linux and Windows on my laptop try AAAA record addresses if they are returned. But since the misconfigured "router" does not return no route to host, my system will sit endlessly trying to connect as the packets are lost. It doesn't failover to IPv4 without waiting for a very long time (on the order of minutes) if it fails over at all. Clearly, this is problematic, though I can work around it by disabling autoconfiguration selectively on their network. After significant discussion they did admit this is a problem especially given the fact that Mac OS X and the upcoming Windows Vista perform AAAA queries out of the box and perform autoconfiguration. However, they also feel this is at least somewhat a "client side" problem and that they cannot neccessarily deal with any rogue advertisements that show up. I'm trying to find some info about dealing with hosts which claim to provide prefixes but don't really route them, both so I can pass this on to them, as well as to bundle into an FAQ. Obviously, one can disable autoconfiguration while on the affected network but this isn't a great solution and it basically breaks a major feature of the protocol. Thanks for your assistance.