What configure mode you used for the command ip ospf authentication-key (something) ?
A.
global
B.
priviliged
C.
in-line
D.
…
Explanation:
BD
ip ospf authentication-key is used under interface configuration mode, so it’s in interface level, under global
configuration mode. If it asks about interface level then choose that.
interface Serial0
ip address 192.16.64.1 255.255.255.0
ip ospf authentication-key c1$c0