Which command do you enter to enable authentication for OSPF on an interface?
A. router(config-router)#area 0 authentication message-digest
B. router(config-router)#ip ospf authentication-key CISCOPASS
C. router(config-if)#ip ospf message-digest-key 1 md5 CISCOPASS
D. router(config-if)#ip ospf authentication message-digest
D is the right one.
D.
https://community.cisco.com/t5/networking-documents/ospf-authentication/ta-p/3131640
B) Enabling OSPF Authentication:
OSPF authentication can be enabling in two ways:
1) Per interface: Authentication is enabling per interface using the “ip ospf athentication” command.
2) Area authentication: Authentication for area can enable using “area authentication” comman
From Netacad.com CCNA security course:
Enable OSPF MD5 authentication globally:
ip ospf message-digest-key key md5 password interface configuration command.
area area-id authentication message-digest router configuration command.
This method forces authentication on all OSPF enabled interfaces.
****If an interface is not configured with the ip ospf message-digest-key command, it will not be able to form adjacencies with other OSPF neighbors.******
Enable MD5 authentication on a per interface basis:
ip ospf message-digest-key key md5 password interface configuration command.
ip ospf authentication message-digest interface configuration command.
I think it is C
Yes, it’s D
I agree with “D” is the correct answer
D. router(config-if)#ip ospf authentication message-digest