When you do conn.open() IIS opens a physical connection to DB.
When u do conn.close() IIS moves to the connection pool.
If some request is made using the same connection string IIS will use it.
In the same app if you do:
IIS will use the same physical connection.
But if you do:
IIS will open two physical connections.
You can return the 2 connections to pool by doing
If you do not close connections conn1 and conn2 will remain open for a long time and wont return to connection pool.
So if there are new connection like conn3 and conn4, IIS will have a total 4 physical connections. If your website hits traffic on black friday, there will be hundreds of such connections which will crash your site :).