This is an old post, but I will post it here so others and myself could check this Kerberos authentication setting.

According to MSDN, you could check Kerberos login from application server (or whatever server that the client requested) event viewer (Security). I found another [blog][1] that also mention how to check Kerberos working.

If client successfully authenticate using Kerberos it will show

    Logon Process: Kerberos
    Authentication Package: Kerberos

[![Event Viewer][2]][2]

In KList command it will also display Kerberos, like this picture.

[![KList][3]][3]


  [1]: https://blog.blksthl.com/2012/09/26/the-final-kerberos-guide-for-sharepoint-technicians/
  [2]: https://i.sstatic.net/iY6CF.png
  [3]: https://i.sstatic.net/DVpv9.png