ENARSI Exam - Question 571

Question

Refer to the exhibit. Which configuration resolves the issue?

Examice · Accepted Answer

The OSPF adjacency issue is caused by a mismatch in authentication configuration. The configuration for the neighbor (cryptographic authentication enabled with HMAC-SHA-256) suggests that a key chain with HMAC-SHA-1 algorithm is required. The correct configuration to resolve the issue should include setting up a key chain with the required cryptographic algorithm and applying it to the interface. Therefore, the correct option is the one that configures the OSPF authentication with a key chain using HMAC-SHA-1.

Pietjeplukgeluk · Answer

Seems:"Rollover in progress, 1 neighbor(2) using old key(s): key id 1 algorithm MD5"
Indicated neighbor uses MD5 authentication.

To fix please set MD5 authentication configuration back:

CSR103(config)#interface fastEthernet 0/0
CSR103(config-if)#ip ospf message-digest-key 1 md5 cisco
CSR103(config-if)#ip ospf authentication message-digest

Above will automatically "remove" wrongly configured "ip ospf authentication key-chain ospf"

[Removed] · Answer

B is corerct

bk989 · Answer

C is currently configured on the router, but with a different hma-sha-256:
show ip ospf interface e0/0
 Cryptographic authentication enabled
    Sending SA: Key 1, Algorithm HMAC-SHA-1 - key chain ospf

ENARSI Exam - Question 571

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