Which of the following relies on the use of shared secrets to protect communication?

A.
RADIUS

B.
Kerberos

C.
PKI

D.
LDAP

Explanation:
Obfuscated passwords are transmitted by the RADIUS protocol via a shared secret and the MD5 hashing algorithm.
Incorrect Answers:
B: Kerberos works on the basis of ‘tickets’ to allow nodes communicating over a non-secure network to prove their identity to one another in a secure manner.
C: A public key infrastructure (PKI) is a set of hardware, software, people, policies, and procedures needed to create, manage, distribute, use, store, and revoke
digital certificates
D: The Lightweight Directory Access Protocol (LDAP) is an open, vendor-neutral, industry standard application protocol for accessing and maintaining distributed
directory information services over an Internet Protocol (IP) network.

http://en.wikipedia.org/wiki/RADIUS
http://en.wikipedia.org/wiki/Kerberos_%28protocol%29
http://en.wikipedia.org/wiki/Public_key_infrastructure
http://en.wikipedia.org/wiki/Lightweight_Directory_Access_Protocol