1. A method comprising: forming a plurality of reports by a plurality of nodes, each node comprising a processor, a memory, and a network connection device interconnecting the nodes in a network, wherein each report: is formed by a respective node; and includes trace data obtained from the respective node and at least one other node; detecting by the processor an inconsistency in the trace data in a first report when compared with corresponding said trace data in a second report, wherein the detecting comprises: constructing an inconsistency graph having vertices that reference one or more nodes; adding an edge between at least two of the vertices if the referenced one or more nodes report inconsistent trace data; and deriving a set of nodes that explain the inconsistent trace data that is reported as a set of vertices in the inconsistency graph having a fewest number of vertices that cover the inconsistency graph; and finding a set of nodes that formed at least the first and second reports having the inconsistency in the trace data.