Exam C2150-609 topic 1 question 13 discussion

A stateful junction /WebApp is added to a Web reverse proxy instance with two backend HTTP servers. When one of the backend server stops responding to the requests, the users are getting the "Third Party Not Responding" error message even though one of the backend server continues to respond.
Which parameter needs to be added to the configuration file so that "Third Party Not Responding" error page is not rendered and the user is connected to the backend server that is responding?