I am trying to find out why there is no Kerberos authentication on my SQL instance :

SELECT COUNT (auth_scheme) as nb, auth_scheme --net_transport, client_net_address 
FROM sys.dm_exec_connections
GROUP BY auth_scheme

nb auth_scheme

2 (Unknown)

151 NTLM


Using KerberosConfigurationManager, requiered SPNs seems to be correctly and automatically registered:

enter image description here

Here's the error log regarding the SPN for the instance :

enter image description here

Could you provide ideas to investigate why there is no Kerberos authentication?

All the conditions list at this Microsoft Docs page have been met.


Cannot add the output because this is confidential info, but the instance is correctly registered :


  • There are no duplicate SPNs? What does the SQL Server error log show, SPN-related? – Max Vernon May 3 '18 at 12:31
  • No there is no duplicate SPN, you can see entries twice because there are 2 sql server instances running on the same server. the sql server log show SPN registration (instance name + dynamic port) for the related instance – Mickael May 3 '18 at 12:49
  • run setspn -L <domain\account>, and add the output to your question with the edit link. BTW, It's better to add the detail as text not and image. – Max Vernon May 3 '18 at 13:45
  • edit added to the post – Mickael May 3 '18 at 15:23
  • Are the clients connecting from a remote host using host name that matches the SPN? – David Browne - Microsoft May 3 '18 at 15:59

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.