What is the best way to resolve this issue?

Refer to the exhibit.

What is the best way to resolve this issue?
A . Install a server certificate signed by a well-know public CA on the WL
C . Disable certificate checks on the client.
D . Install a server certificate signed by a well-known public CA on the Radius Server
E . Use the certificate authority on the Cisco Identity Services Engine.

View Answer

Answer: C

Explanation:

From: Event: 5400 Authentication failed Failure Reason: 12321 PEAP failed SSL/TLS handshake because the client rejected the ISE Local C certificate

Cisco ISE authentication failed because client reject certificate | AAA, Identity and NAC | Cisco Support Community https://supportforums.cisco.com/discussion/11697966/cisco-ise-authentication-failed-because­client-reject-certificate

The error you are seeing in ISE is pointing to your client, if you have the eap settings set to "validate server certificate" then you must manually set it to trust the rootCA that signed the ISE certificate, or you can disable this option for testing. You can try to remove this wireless network profile, and recreate it and see if the popup appears which asks you to validate the server’s identity..

Note: This is an indication that the client does not have or does not trust the CiscoISE certificates. Possible Causes The supplicant or client machine is not accepting the certificate from Cisco ISE. The client machine is configured to validate the server certificate, but is notconfigured to trust the Cisco ISE certificate. Resolution The client machine must accept the Cisco ISE certificate to enable authentication. certificate signed by unknown authority

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https://supportforums.cisco.com/discussion/11697966/cisco-ise­authentication-failed-because-client-reject-certificate

Possible Causes for this The supplicant or client machine is not accepting the certificate from Cisco

issue ISE. The client machine is configured to validate the server certificate, but is not configured to trust the Cisco ISE certificate.