1. A method comprising: identifying a set of network nodes within a network; iteratively filtering the set of network nodes in accordance with a testing policy comprising at least one policy rule, wherein iteratively filtering comprises: in an initial iteration, filtering out network nodes that are endpoints of the network from the set of network nodes; for each subsequent iteration: determining a filter criteria from one or more of the policy rules; filtering out network nodes from the set of network nodes produced by the immediately previous iteration based on the filter criteria; invoking a network test scheme that is compliant with the testing policy and is limited to execution against the set of network nodes produced by the iterative filtering.