Testing CORS Locally

I have an Api that accepts CORS requests.

I tried to test this application by reassigning my hostsfile to c:\windows\System32\drivers\etc\hostsas follows:

127.0.0.1 localhost.mydomain.com

So, I disabled my calling application:

localhost.mydomain.com

And my Api is off:

localhost

And found that the Api call returned Error: Access denied.in IE10

However, in Chrome, the same configuration worked fine.

Then I searched for a while, I understand that IE10 fully supports CORS, so I was surprised that this did not work.

I eventually got CORS requests to work with another entry in my hosts file

127.0.0.1 localapi.mydomain.com

Is there anything specific that stops IE10 that can call Localhost in another domain?

thank