Abstract: Systems and methods for locating network errors. The system includes a plurality of host nodes in a network of host nodes and intermediary nodes, and a database storing route data for each of a plurality of host node pairs. The system includes a controller configured to identify a subject intermediary node to investigate for network errors and select, using route data stored in the database, a set of target probe paths. Each target probe path includes a respective pair of host nodes separated by a network path including at least one target intermediary node, which is either the subject intermediary node or an intermediary node that is a next-hop neighbor of the subject intermediary node. The controller is configured to test each target probe path in the set of target probe paths and to determine, based on a result of the testing, an operational status of the subject intermediary node.