load balancing decision and cookie persistence

Or maybe if I try a http cookie passive method with fallback src_ip persistence. In this case If in the 1st request from the customer the correct cookie key value that maps to the correct pool member is added in the header, will it work to direct to the correct pool and persist on it? and if the cookie is not inserted in the header or not the correct one, then it will fallback to src_ip persistence? In this case we will avoid irule. My question here if the logic is right, then what will happen regarding load balancing if no persistence record is matched.