Execute the following command (command prompt) on your sql server:

sqlcmd -L


Note: -L must be uppercase!

Lists the locally configured server computers, and the names of the server computers that are broadcasting on the network. This parameter cannot be used in combination with other parameters. The maximum number of server computers that can be listed is 3000. If the server list is truncated because of the size of the buffer a warning message is displayed.

For more info: