A network endpoint may issue network traces directed to another endpoint. Completed traces may provide information pertaining to possible paths between the endpoints. In response to a failed trace, a component along a possible path between the endpoints may be associated with a value that indicates an assessed contribution of the component to the network failure. The value may be used to initialize a parameter to a statistical calculation that iteratively refines the estimate to form a probability estimate regarding a likelihood that the component is contributing to a network fault.