port number of SQL Server

Solution 1:

The default instance uses port 1433. Named instances will use dynamically negotiated ports (but can be configured to listen on specified ports-- see http://msdn.microsoft.com/en-us/library/ms177440.aspx).

Edit:

By default when a named instance of SQL Server starts it chooses a randomly unused port and registers that with the SQL Browser service. Clients send requests to that service (UDP port 1434) to retrive the port number for the instance they're trying to connect. You are correct in that the dynamic port number will remain the same throughout a single execution of a given instance. If you stop / restart that instance, though, the port number will change. So, there is no "fixed" value for the dynamic port.