Answer by Adrian Morson for Error: Cannot Generate SSPI context

Cannot generate SSPI context can mean exactly that. When a client connects to an SQL server it uses a generation method that includes the service type (MsSQLsvr) Server FQDN and port. It uses DNS to generate the server name so if it resolves the name incorrectly due to CNAMEs or host file etc the generation will fail. Ping the desired server and see what reply you get. If it isn't the FQDN of the SQL server then the SPN will be generated incorrectly causing this error.