To test the online responder, you can create a new computer certificate. After you have exported this certificate to a CER file, run certutil –URL c:\temp\MyCertificate.cer. This command opens the window as shown below.
URL Retrieval Tool
Select OCSP and click on Retrieve. The status of this certificate should change to Verified. Now, you can revoke this certificate on your CA and publish the CRL again. If you click again on Retrieve now, the status should change to Revoked.