Which two statements about using the CHAP authentication mechanism in a PPP link are true? (Choose two)
A. CHAP users a two-way handshake
B. CHAP authentication periodically occurs after link establishment.
C. CHAP uses a three-way handshake
D. CHAP authentication is performed only upon link establishment.
E. CHAP authentication passwords are sent in plaintext.
F. CHAP has no protection from playback attacks.
