It depends on what exactly you are trying to find out.
If you are wanting to know if SQL Server is installed, there is not a real way to do that from a PC connected to the network. There are many reasons a SQL Server would not show up in your list. You would have to use an "inventory scanner", like SCOM or MAP, which scans a machine for applications.
If you are trying to find how to connect to a remote SQL Server, again, there is no way to do that from a PC. There are some ways to "listen" to browser broadcasts, but those are not reliable and can be turned off.