How to: Enable Kerberos Authentication on a SQL Server Failover Cluster
Kerberos is a network authentication protocol designed to provide strong authentication for client/server applications. Kerberos provides a foundation for interoperability and helps to enhance the security of enterprise-wide network authentication.
You can use Kerberos authentication with SQL Server stand-alone instances or with SQL Server failover cluster instances. For additional information, see Registering a Service Principal Name and the Knowledge Base article, "How to use Kerberos authentication in SQL Server."