300-101 Question 16
Which PPP authentication method sends authentication information in cleartext?
A. MS CHAP
B. CDPCP
C. CHAP
D. PAP
Correct Answer: D
Explanation/Reference:
PAP authentication involves a two-way handshake where the username and password are sent across the link in clear text; hence, PAP authentication does not provide any protection against playback and line sniffing.
CHAP authentication, on the other hand, periodically verifies the identity of the remote node using a three-way handshake. Afte r the PPP link is established, the host sends a "challenge" message to the remote node. The remote node responds with a value calculated using a one-way hash func tion. The host checks the response against its own calculation of the expected hash value. If the values match, the authentication is acknowledged; other wise, the connection is terminated.
Reference: http://www.cisco.com/c/en/us/support/docs/wan/point-to-point-protocol-ppp/10241- ppp-callin-hostname.html
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