ASP.NET 2010 connect to database question

Question

I am working on a C# 2010 web form application that uses linq to sql connections. In the  various *.dbml files that are used, most of the .dbml files use the following connection string:

ConnectionString1 (Web.config), that  points to the web.config file.

However in one of the situations, one .dbml file points to

DBConnectionStrings2 (Settings).

Thus can you tell me where the DBConnectionStrings2 (Settings) is referring to? What is the settings that are being referred to?