How to Get Window NT Logged User Name Using ASP.NET

1) System.Security.Principal.WindowsPrincipal p = System.Threading.Thread.CurrentPrincipal as System.Security.Principal.WindowsPrincipal;

string strName = p.Identity.Name;

2) string strName = HttpContext.Current.User.Identity.Name.ToString();

3) string strName = Request.ServerVariables["AUTH_USER"]; //Finding with name

string strName = Request.ServerVariables[5]; //Finding with index