URL concatenation in VS2013

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C#

Hi Friends,
I am developing web project in C# VS 2013.
i give URL link to menus.
i have the following menus:
Home,Course,Application,Contact
URL for menus:
Home->/Default
Course->/PageInfo/Course
Application->/PageInfo/Application
Contact->/Contact
below is my Routeconfig code

// Register a route for Page/{PageName}
          routes.MapPageRoute(
             "Page Informations",           // Route name
             "PageInfo/{PageInfo}",                  // Route URL
             "~/Page.aspx"              // Web page to handle route
          );

          routes.MapPageRoute(
         "Home Page",           // Route name
         "Home",                  // Route URL
         "~/Default.aspx"              // Web page to handle route
     );
          routes.MapPageRoute(
      "Contactus Page",           // Route name
      "Contact",                  // Route URL
      "~/Contact.aspx"              // Web page to handle route
  );

if i click Course page, the URL automatically changed as following:
Home->PageInfo/Default
Course->PageInfo/PageInfo/Course
Application->PageInfo/PageInfo/Application
Contact->PageInfo/Contact

anyone knows why the URL Concatenate with others like this.
here my menu code

<ul id="nav">
                <li><a href="Default.aspx">Home</a></li>
                <li><a href="PageInfo/Course">Course</a></li>
                <li><a href="PageInfo/faculty">Faculty</a></li>
                <li><a href="PageInfo/Application">Application</a></li>
                <li><a href="ReachUs">Reach Us</a></li>
                <li><a href="Contact.aspx">Contact Us</a></li>
</ul>