Configuring Kerberos Authentication

Configuring Kerberos Authentication (requires registration) but a very good article

http://www.sqlservercentral.com/articles/Security/65169/#

The query to check connections on SQL server (including their authentication type) is

   1:  SELECT

   2:  s.session_id

   3:  , c.connect_time

   4:  , s.login_time

   5:  , s.login_name

   6:  , c.protocol_type

   7:  , c.auth_scheme

   8:  , s.HOST_NAME

   9:  , s.program_name

  10:  FROM sys.dm_exec_sessions s

  11:  JOIN sys.dm_exec_connections c

  12:  ON s.session_id = c.session_id

Kerberos is configured usually using an Active Directory admin account and the utility SETSPN to set the service principle names required for proper operation.