Ramblings from another nerd on the grid
Kerberos authentication provides a highly secure method to authenticate client and server entities (security principals) on a network. To use Kerberos authentication with SQL Server, a Service Principal Name (SPN) must be registered with Active Directory, which plays the role of the Key Distribution Center in a Windows domain. In addition, many customers also enable delegation for multi tier applications using SQL Server. In such a setup, it may be difficult to troubleshoot the connectivity problems with SQL Server when Kerberos authentication fails.
The Kerberos Configuration Manager for SQL Server is a diagnostic tool that helps troubleshoot Kerberos related connectivity issues with SQL Server. It can perform the following functions:
Go get it @ http://www.microsoft.com/en-us/download/details.aspx?id=39046.