Is it possible to make the ssh client not care what IP a ssh server is behind (and if a different server was behind that IP earlier) but instead trust specific server keys? (And maybe nickname those keys?) I use dynamic DNS and I have IPv6 privacy extensions enabled on some computers and am always getting asked if it think it's safe to connect. Another possibility is addresses assigned by DHCP getting assigned to different ssh servers and causing all sorts of 'key doesn't match IP' errors.