You are selecting an authentication method for your company's servers. You are looking for a method that periodically re-authenticates clients to prevent session hijacking. Which of the following would be your best choice?

The correct answer is that Challenge Handshake Authentication Protocol (CHAP) periodically has the client re-authenticate. This is transparent to the user but is done specifically to prevent session hijacking. Password Authentication Protocol (PAP) is actually quite old and does not re-authenticate. In fact, it even sends the password in cleartext, so it should not be used any longer. SPAP (Shiva Password Authentication Protocol) adds password encryption to PAP but does not reauthenticate. OAuth is used in web authentication and does not reauthenticate.