Getting CORS issue when passing x-auth-token to headers from ajax request

I am getting CORS error when passing x-auth-token to my ajax request. When I knock off the auth code then the CORS issue is getting resolved. But for my application, I do need the authentication and x-auth to be passed.

Below is my code:

<script>


window.onload = function() {
    var username1 = 'username';
  fetchData(username1);
};
function fetchData(username1) {

    $.ajax({
        type:'post',
        url: 'http://xample.com/lcc_Overview.php',
        dataType: 'json',
        headers: {'Access-Control-Allow-Headers': 'Content-Type, Authorization, Content-Length, X-Requested-With'*/ 
                'Access-Control-Allow-Origin': '*',
                'x-auth-token': 'asjgkasjhgusigjkascbjhsgajghjagsdjdhhjsdhj'
        },
        data:
            {
                username:username1,
                courseid:1994
            },
        success: function(result) {
            console.log(result);
        }
        });
        }

</script>

Can anyone suggest me why the CORS error is getting for x-auth and how it can be resolved.