Esri Javascript - HttpGet call on a Windows AD authentication application with .net API

Question

I need to make an API call to my .NET 4.5.1 application that uses Windows AD for authentication. Making the call via Dojo/Request and Esri/Request, I am returned with a UNAUTHORIZED response code. I need to find the correct syntax for passing Username and Password to an API endpoint which uses Windows AD.

esri/Request (returns UNAUTHORIZED):

  var requestHandle = esriRequest({
     "url": "https://myWindowsADwebsite.net/api/contact/get"}, 
         {headers : {"Username": "myUser", "Password": "myPass" }
   });
 requestHandle.then(this.requestSucceeded, this.requestFailed);

Dojo/Request (returns UNAUTHORIZED):

request("https://myWindowsADwebsite.net/api/contact/get/", {
             headers: {
            "Username": "myUser",
            "Password" : "myPass"
        }

There is a way to pass credentials to a Windows AD endpoint, but it is not via the headers based on what I have tested. All help is appreciated.