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How to set the correct SPN for a storage controller

Last Updated:

Applies to

  • Data ONTAP 8 7-Mode
  • Data ONTAP 7 and earlier


  • There are times when the Service Principal Name (SPN) defined during CIFS Setup does not match the required SPN that a client attempts to look up.
    • This results in the following error being identified in the packet trace: KRB_ERR_S_PRINCIPAL_UNKNOWN
    • This in turn, causes the Microsoft Client to fall back and then use NTLM for authentication instead of Kerberos.
  • There are three common causes for this:
    • When CIFS setup was run on the storage controller, the value defined in options dns.domainname did not match the FQDN of the domain that was being joined.
    • When clients attempt to access the storage controller, they are using a Netbios Alias.
    • When clients attempt to access the storage controller, they are using a DNS Alias.


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