How to list available SQL Server instance in a network?

I want to write a program that allows user to select one SQL Server instances in an network. How can I list available instances in a C# program?

Addition questions: How can I know that a database is currently mirroring? Is there a way to kno开发者_如何转开发w what instance is it's partner and it's witness?

Thank you very much!

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This may help http://www.zuhaib.in/how-to/c-sharp-obtain-list-of-sql-server-instances