I am running into this error on my PDC. I can't log into the server with any accounts, but I do have member servers. Full error:
The KDC encountered duplicate names while processing a Kerberos authentication request. The duplicate name is cifs/ (of type DS_SERVICE_PRINCIPAL_NAME). This may result in authentication failures or downgrades to NTLM. In order to prevent this from occuring remove the duplicate entries for cifs/ in Active Directory.
When I run setspn -X the query doesn't have any results. I am not 100% sure how to find the duplicate accounts other than what shows in the event viewer. I have two accoutns showing cifs/ and host/. I am not sure the best way to remove them as well.
Any thoughts there?