SQL Server Authentication

Classification:
Windows Authentication mode and Mixed mode
Platform:
Windows
Properties:
Authentication Mode

The differences between these two types of authentication modes are:
(1) Windows authentication Mode
Only Windows authentication is performed. The user cannot specify a SQL Server 2000 login ID. This is the default authentication mode for SQL Server 2000. You cannot specify Windows Authentication mode for an instance of SQL Server that is running on Windows 98 because this operating system does not support Windows authentication.
(2) Mixed mode
If a user provides a SQL Server 2000 login ID at logon, the system validates it with SQL Server authentication. If you do not provide a SQL Server 2000 login ID or request Windows authentication, use Windows authentication to authenticate it.
These modes are specified during installation or by using SQL Server Enterprise Manager.
Windows authentication has some advantages over SQL Server authentication, primarily due to its integration with Windows NT 4.0 and Windows 2000 security systems. Windows NT 4.0 and Windows 2000 security systems provide more features such as security authentication and password encryption, auditing, password expiration, minimum password length, and locking accounts after multiple logon requests are invalid.
Because Windows NT 4.0 and Windows 2000 users and groups are maintained only by Windows NT 4.0 or Windows 2000, when a user connects, SQL Server reads the membership information about the user in the group. If changes are made to the accessible permissions of the connected user, the changes take effect the next time the user connects to the SQL Server instance or logs on to Windows NT 4.0 or Windows 2000 (depending on the type of change).
Description: Windows Authentication mode is not available when the instance of SQL Server is running on Windows 98 or Microsoft Windows Millennium Edition.

SQL Server Authentication