Sql-server – where to see SQL Server start/stop logs

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.

This could also be caused by having the AUTO_CLOSE option set to ON. When this is the case, the database will be stopped after the last user connection to that database is closed. The database will be started again when a new connection is made to the database. The default for SQL Express editions is ON, and OFF for all other server editions.

When set to ON, the database is shut down cleanly and its resources are freed after the last user exits. The database automatically reopens when a user tries to use the database again.

When set to OFF, the database remains open after the last user exits.