During cluster fallover testing，the administrator determines that additional work is required to stop existing test applications on the standby node，prior to starting the production applications on the surviving node.  To manage this type of requirement，which step should be performed first？（）  

• A、 Create a custom pre/post event.
• B、 Add a custom user defined event.
• C、 Define custom error notification.
• D、 Modify the test application server.