How do you handle outdated pages? A p2p file sharing is one thing. A file is pretty static, but websites change very often. By the time your file got shared all

How do you handle outdated pages? A p2p file sharing is one thing. A file is pretty static, but websites change very often. By the time your file got shared all the way across the planet you might be already displaying something else. Do they all have to keep track of the original file?