How to route this in ASP MVC - asp.net-mvc

Question

This is my first ASP MVC project so I'm not sure how to do this.
I have a section called Admin, which has an Admin controller. I'm using this for just an index page.
In the Admin section, there are different sections. Let's say Company and Line Of Business
I want to handle everything for those in their own CompanyController and LineOfBusinessController
I want the routes to be prefixed with Admin though ie. Admin/Company, Admin/Company/Add
I have achieved this by adding a route before the Default route that is this
routes.MapRoute(
name: "Admin",
url: "Admin/{controller}/{action}/{id}",
defaults: new { controller = "Admin", action = "Index", id = UrlParameter.Optional }
);
The problem is now all my routes choose this one over the default, meaning everything else becomes Admin/Section ie Admin/Home etc.....
I tried using Html.RouteLink instead of ActionLink and the URL's were formatted correctly, but when I go to Admin/Company it can't find because it assumes Company is in AdminController
How can I route this properly?
EDIT
Here are my routes, and then my links
public static void RegisterRoutes(RouteCollection routes)
{
routes.IgnoreRoute("{resource}.axd/{*pathInfo}");
routes.MapHttpRoute(
name: "DefaultApi",
routeTemplate: "api/{controller}/{id}",
defaults: new { id = RouteParameter.Optional }
);
routes.MapRoute(
name: "Admin",
url: "Admin/{controller}/{action}/{id}",
defaults: new { controller = "Admin", action = "Index", id = UrlParameter.Optional }
);
routes.MapRoute(
name: "Default",
url: "{controller}/{action}/{id}",
defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional }
);
}
Links
<li>#Html.ActionLink("Home", "Index", new { controller = "Home" }, ViewBag.SelectedNav == "Home" ? new { #class = "active" } : null)</li>
The link ends up /Admin/Home
UPDATE
Did not mark an answer here as I ended up exploring, and ultimately using Areas. It was suggested in the one answer, but the rest of the answer is not correct so I did not want to mislead anyone. Thanks for the Area suggestion however

Answer 1

Have the generic routing below your specific one. The order of routing definition is important. When MVC finds a matching route for a request, it won't process the rest.
routes.MapRoute(
name: "Admin",
url: "Admin/{controller}/{action}/{id}",
defaults: new { controller = "Admin", action = "Index",
id = UrlParameter.Optional }
);
routes.MapRoute(
"Default", // Route name
"{controller}/{action}/{id}", // URL with parameters
new { controller = "Home", action = "Index",
id = UrlParameter.Optional } // Parameter defaults
);
Also it is better for your to use Areas in this scenario. It is a better approach when you want to structure your app in to different sections like Admin / Normal user etc..

Answer 2

Since I don't know what the link behavior should be, the best thing I can suggest is to debug your routes and see which route is handling which URL's.
1) Go into Visual Studio and install the RouteDebugger
PM> Install-Package routedebugger
2) Add some code to your global file
protected void Application_Start(object sender, EventArgs e)
{
RegisterRoutes(RouteTable.Routes);
RouteDebug.RouteDebugger.RewriteRoutesForTesting(RouteTable.Routes);
}
3) Run your site and request your questionable links.
4) Review your results and modify accordingly
Edit: it appears as though RouteDebugger v2 is now RouteMagic
PM> Install-Package RouteMagic
And you can find the source code on github