How to enable cors on a different site collection?

Question

I want to make a rest call to get web properties (i.e. /_api/web), for a different web application than the current. I have added the response headers

Access-Control-Allow-Credentials : true
Access-Control-Allow-Origin : *
Access-Control-Request-Method : GET,POST,HEAD,OPTIONS

in IIS.

Then I tried to make a ajax call

    $.support.cors = true;
    $.ajax({
        url: "http://othersite/_api/web",
        type: "GET",
        //timeout: 8000,
        //contentType: "application/json;odata=nometadata",
        //cache: false,
        crossDomain:true,
        headers: {
            "Accept": "application/json;odata=verbose"
        },
        xhrFields: { withCredentials: true },
        success: function(data) {
            console.log('worked');
        },
        error: function(jqXHR, textStatus, errorThrown) {
            console.log('error');
        }
    });

but it doesn't work. I get 401 unauthorized. Does anyone know what is wrong?

Thanks

I even tried this

http://www.thesharepointguide.com/create-a-list-item-in-another-site-collection/

but same problem.