Hmm it was wild guess, some time ago I've learnt that SQL in local connection can fall back to NTLM. But if you still see NTLM from a remote machine, you can check this article.

http://mssqlwiki.com/2013/12/09/sql-server-connectivity-kerberos-authentication-and-sql-server-spn-service-principal-name-for-sql-server/