I have an SQL server with 3 instances on it. If I connect to it with Management Studio i automatically connect to one of the instances. the same each time.
It looks like there is a default named instance between the instances.... is that true? and will it be the same thing if i connect withour an instance name from another client than Management Studio (fx a SSIS package)?
Thx Nicolaj
The SQL Server browser service is responsible for directing connections into the server to the appropriate instance of SQL Server. When you connect to SQL Server using only the computer name, it assumes that you are connecting to the default instance and directs you to port 1433. When you connect to a named instance, it takes the name of the instance and translates that to the port that that instance is listening on (by default it uses dynamic ports). You could bypass the browser service altogether and just connect directly to the port that you want, the name is just a shortcut to keep you from having to look up the port all the time.
If you take one of your named instances and change the port from dynamic to 1433, you will be able to connect to it with only the server name since 1433 is the default port. So in your case, either you have 2 named instances and one default instance and you're connecting to the default instance every time, or someone has changed the port of one of your named instances to 1433.