I am currently experimenting with ipv6 via tunnels & have one working at home fine.
I have not got round to adding ipv6 support to server yet but I have noticed that plesk dont seem to support it (IP add is for dotted quad only & no ipv6 dns options)
Is this because ipv6 is not enabled on server yet & as such plesk dont think i need it or does plesk just not have any ipv6 support?