Hi Ning Li,
The thing is this I managed to get the SNC working, with out any maintaining user in su01, as I am using with out logon option in the Network tab, but only on the application server. BUT, the problem is this now, I am trying to login in to the server that is not on the domain as the sap is installed I am able to connect to the server with out the SNC enabled. Hence the earlier screenshot which I am getting the error.