title: Determining the name of a dropdownlist control that caused a post back onchange event in MVC
body: <p>I have two html helper dropdownlists for displaying districts and towns in my mvc web application. I am using vb.net
  below is two of my drop down lists in the view layer. </p>
  
  <pre><code>    @*Dropdownlist1*@
  
      @Html.DropDownList("Districts", Nothing, "All",
          htmlAttributes:=New With {.class = "form-control", .onchange = "$(this).closest('form').submit();"})
  
      @*Dropdownlist2*@
  
      @Html.DropDownList("Towns", Nothing, "All",
              htmlAttributes:=New With {.class = "form-control", .onchange = "$(this).closest('form').submit();"})
  </code></pre>
  
  <p>In my server side code, i need to know which of the two dropdownlists controls caused the post back after selection /change. 
  i need a way of passing the dropdownlist name, or an equivalent as part of the values that are submitted.</p>