Microsoft SQL Server can run on a network, or it can function without a network.
Running SQL Server on a Network
For SQL Server to communicate over a network, the SQL Server service must be running. By default, Microsoft Windows automatically starts the built-in SQL Server service. To find out whether the SQL Server service has been started, at the command prompt, type the following:
If the services associated with SQL Server have been started, the following services will appear in the net start output:
Analysis Services (MSSQLSERVER)
SQL Server (MSSQLSERVER)
SQL Server Agent (MSSQLSERVER)
Running SQL Server Without a Network
When running an instance of SQL Server without a network, you do not need to start the built-in SQL Server service. Because SQL Server Management Studio, SQL Server Configuration Manager, and the net start and net stop commands are functional even without a network, the procedures for starting and stopping an instance of SQL Server are identical for a network or stand-alone operation.
When connecting to an instance of a stand-alone SQL Server from a local client such as sqlcmd, you bypass the network and connect directly to the instance of SQL Server by using a local pipe. The difference between a local pipe and a network pipe is whether you are using a network. Both local and network pipes establish a connection with an instance of SQL Server by using the standard pipe (\\.\pipe\sql\query), unless otherwise directed.
When you connect to an instance of a local SQL Server without specifying a server name, you are using a local pipe. When you connect to an instance of a local SQL Server and specify a server name explicitly, you are using either a network pipe or another network interprocess communication (IPC) mechanism, such as Internetwork Packet Exchange/Sequenced Packet Exchange (IPX/SPX) (assuming you have configured SQL Server to use multiple networks). Because a stand-alone SQL Server does not support network pipes, you must omit the unnecessary /<Server_name> argument when connecting to the instance of SQL Server from a client. For example, to connect to a stand-alone instance of SQL Server from osql, type:
osql /Usa /P <saPassword>