Search all running SQL Server instances over LAN

Sometimes you need to know how many and what instances of SQL Server running in your organization over Network. You can easily see in simple steps

•    Go to SSMS.
•    Object Explorer
•    Click on Connect

•      Go to Server Name Dropdown and Select Browse for More

There are two options Local Servers and Network Servers.

•           Local Servers: It lists all instances installed on your local machine.
•       Network Servers: It lists all instances installed on your Network.

Further,There are various utilities with more functionality to achieve the same.

I find some utility as

·       Quest Discovery Wizard for SQL Server 

Quest Discovery Wizard for SQL Server makes it simple to detect all the SQL Server instances in your organization and monitor your network for changes. It even helps you find SQL Server instances that native tools cannot detect.

With Discovery Wizard, you can:

Create an inventory of the databases on your network and the amount of data they contain

Select databases for consolidation

Review database history, including installation and creation dates

Find out which SQL Server versions and service packs are deployed

Learn server, instance, and operating system names

See who your end users are.

                         http://www.quest.com/discovery-wizard-for-sql-server/

·        The Microsoft Assessment and Planning Toolkit

The Microsoft Assessment and Planning Toolkit make it easy to assess your current IT infrastructure for a variety of technology migration projects. This Solution Accelerator provides a powerful inventory, assessment, and reporting tool to simplify the migration planning process.

      http://blogs.msdn.com/b/petersad/archive/2012/11/09/using-the-map-toolkit-8-0-beta-to-discover-sql-server-instances.aspx