Ques 1. Which protocols are supported by SQL Server and how are they used?
In SQL Server, there are 4 protocols.
• Shared memory (for local connections and troubleshooting purpose).
• Named pipes (for connections which are in LAN connectivity).
• TCP/IP (for connections which are in WAN connectivity).
• VIA-Virtual Interface Adapter (requires special hardware to set up by vendor and also deprecated from SQL 2012 version).
Ques 2. What is the default port of SQL Server for connectivity?
TCP port 1433 is the default port for SQL Server.
Ques 3. When you try to connect to SSMS, the following error message appears: "A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections.". What is the most probable cause?
Most likely, your SQL Server service is not running. So go to Services and start your SQL Server Service.
Another reason could be that TCP/IP protocol is disabled for MSSQL protocols. So enable the TCP/IP protocol and restart SQL Server service