What are difference between Default instance and Named instance in SQL Server?
A SQL Server installation is referred to as an instance. Up to and including SQL Server 7.0, only one installation of SQL Server was possible on a server, but that restriction didn’t suit a number of deployment scenarios that customers required, including high-availability and consolidation. With the release of SQL Server 2000, multiple installations of SQL Server were possible on a single server and were known as SQL Server instances. SQL Server 2008 continues with this model and with very few changes. A default instance has much the same profile that SQL Server installations have had in past; you install SQL Server and then connect using the computer name of the server. Your Windows Server can only have one computer name, so you can only use it to connect to one SQL Server instance. This is called the default instance. If you install additional instances of SQL Server, these are referred to as named instances. You connect to them using the <computername><instanc