Which command is used to enable CHAP authentication, with PAP as the fallback method,
on a serial interface?
A.
Router(config-if)# ppp authentication chap fallback ppp
B.
Router(config-if)# ppp authentication chap pap
C.
Router(config-if)# authentication ppp chap fallback ppp
D.
Router(config-if)# authentication ppp chap pap
Explanation:
This command tells the router to first use CHAP and then go to PAP if CHAP isn’t available.