如何在 asp.net MVC 4和 MVC 5中设置默认控制器

the best way is to change your route. The default route (defined in your App_Start) sets /Home/Index

routes.MapRoute(
"Default", // Route name
"{controller}/{action}/{id}", // URL with parameters*
new { controller = "Home", action = "Index",
id = UrlParameter.Optional }
);

as the default landing page. You can change that to be any route you wish.

routes.MapRoute(
"Default", // Route name
"{controller}/{action}/{id}", // URL with parameters*
new { controller = "Sales", action = "ProjectionReport",
id = UrlParameter.Optional }
);

I didn't see this question answered:

How should I setup a default Area when the application starts?

So, here is how you can set up a default Area:

var route = routes.MapRoute(
name: "Default",
url: "{controller}/{action}/{id}",
defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional }
).DataTokens = new RouteValueDictionary(new { area = "MyArea" });

Set below code in RouteConfig.cs in App_Start folder

public static void RegisterRoutes(RouteCollection routes)
{
routes.IgnoreRoute("{resource}.axd/{*pathInfo}");
routes.MapRoute(
name: "Default",
url: "{controller}/{action}/{id}",
defaults: new { controller = "Account", action = "Login", id = UrlParameter.Optional });
}

IF still not working then do below steps

Second Way : You simple follow below steps,

1) Right click on your Project

2) Select Properties

3) Select Web option and then Select Specific Page (Controller/View) and then set your login page

Here, Account is my controller and Login is my action method (saved in Account Controller)

Please take a look attached screenshot.

In case you have only one controller and you want to access every action on root you can skip controller name like this

routes.MapRoute(
"Default",
"{action}/{id}",
new { controller = "Home", action = "Index",
id = UrlParameter.Optional }
);