The temporary 1.11 world is running on the normal buildatnight.com IP. Remember this is a vanilla map. Follow all vanilla SMP precautions. Dont give out your coords to anyone you dont trust completely and dont build close to spawn. (Think a few thousand blocks out) Building a nether portal near your base is almost as dangerous as posting your coords at spawn. Dont do it. Build one farrr away from your base. There is no protection and no rollback in vanilla. People will try to grief you.