The term most of but not exact can be seen when moving from one connection on a router to another where some portion remains the same due to the same account and physical connection of the host. For hiding ip addresses in order to "ghost surf" which can help cut down on spam there are several that simply hide the ip or misdirect through a random series of "bogus" addresses. You first connect to one server that then allows you to connect as a phantom for invisible browsing there.