Refresh only content place holder without refreshing master page

Refresh only content place holder without refreshing master page

• Create menu.ascx and edit as 

<div class="menu">

    <ul>

        <li><a href="Default.aspx?menu=Home">Home</a></li>

        <li><a href="Default.aspx?menu=Admin">Admin</a></li>

        <li><a href="Default.aspx?menu=About">About</a></li>

    </ul>   

</div>

• Create 

1. Home.ascx
2. Admin.ascx
3. About.ascx

• change masterpage.master.cs file

 protected void Page_Load(object sender, EventArgs e)

    {

        LoadMenu();

    }

    private void LoadMenu()

    {

        string menu = Request.QueryString["menu"];

        Control c;

        switch (menu)

        {

            case "Home":

                c = Page.LoadControl(Request.ApplicationPath + "/UserControlMenu/LeftMenuHome.ascx");

                break;

            case "Admin":

                c = Page.LoadControl(Request.ApplicationPath + "/UserControlMenu/LeftMenuAdmin.ascx");

                break;

            case "About":

                c = Page.LoadControl(Request.ApplicationPath + "/UserControlMenu/LeftMenuAbout.ascx");

                break;

            default:

                c = Page.LoadControl(Request.ApplicationPath + "/UserControlMenu/LeftMenuHome.ascx");

                break;

        }

        leftMenuContentPlaceHolder.Controls.Add(c);

    }