Implementing Cisco Network Security (IINS, legacy) — Question 1

Which command do you enter to enable authentication for OSPF on an interface?

Answer options

• 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

Correct answer: C

Explanation

The correct command for enabling OSPF authentication on an interface is 'router(config-if)#ip ospf message-digest-key 1 md5 CISCOPASS', which specifies the key type and value. Options A and D configure authentication at the area level and do not apply directly to an interface. Option B is incorrect because it uses a different command that sets the authentication key for OSPF but not specifically for an interface.