Checking if the query is made async or sync on SQL Server 2008 R2 I have tried to make async calls to my SQL Server instance as you may see on my SO post:

ASP.NET MVC 4 asyncronous database call: never returns the HTTP response

I did a benchmarking and the sync version is better than async one when there is even lots of concurrent loads. I am not sure if I got this right and opened the connection as async to my SQL Server instance.

The query does not take too much time and considering the fact that asynchronous code has much more overhead than the sync one, this might be the issue here as well. On the other hand, honest to say, I am not sure how to check if I opened the connection successfully as async or not.

Is there any chance I could check if the query is successfully completed as asynchronously?
As far as I can tell, SQL Server doesn't know a query is asynchronous. It's always synchronous to SQL Server. The connection string change appears to affect the client only.

sys.dm_exec_connections etc don't have anything to show whether a query is asynchronous or not