<link rel="shortcut icon" type="image/x-icon" href="@Url.Content("~/Content/images/favocin.ico")" />

routes.IgnoreRoute("{*favicon}", new { favicon = @"(.*/)?favicon.ico(/.*)?" });

routes.IgnoreRoute("favicon.ico"); // Подходит, только если favicon.ico находится в корне сайта.

<link rel="shortcut icon" type="image/x-icon" href="@Url.Content("~/Content/images/favocin.ico")" />

            routes.MapRoute(
                "/Content/images/favocin.ico",
                "Content/images/favocin.ico",
                new
                {
                    controller = "Home",
                    action = "Favicon"
                });

            routes.MapRoute(
                "Robots.txt",
                "robots.txt",
                new
                {
                    controller = "Home",
                    action = "Robots"
                });

        #region Service file actions.

        public FileResult Favicon()
        {
            Response.ContentType = "image/x-icon";
            return File("/Content/images/favicon.ico", "image/x-icon");
        }

        //Сделано по 
        //http://geekswithblogs.net/jjulian/archive/2012/04/25/adding-robots.txt-to-your-asp.net-mvc-3-applications.aspx

        public ActionResult Robots()
        {
            Response.ContentType = "text/plain";
            return View("~/Views/Home/ServiceFileViews/Robots.cshtml");
        }

        #endregion Service file actions.

            routes.MapRoute(
                "favicon.ico",
                "favicon.ico",
                new
                {
                    controller = "Home",
                    action = "Favicon"
                });