Abstract: The present invention provides method and apparatus for testing a network, such as a printed circuit board, to check whether it conforms to its design as to having a plurality of network nodes and a predetermined node-connection pattern defining a division of the network nodes into a plurality of groups. In a conforming network, each network node is connected in common to all other network nodes in its group, and is isolated from the network nodes in each other group. In accordance with the invention, one of the network nodes is selected to serve initially as a present FROM node. There is thereafter selected repeatedly, from the network nodes that have not previously served as a present FROM node, a network node to serve temporarily as a present FROM node.