Abstract: A set of computing devices are networked together. Each device maintains data about the other computing devices in the set, namely, a time and location of a last successful connection between the device and one or more of the other devices. The data at a device is updated as computing devices in the set move out of communication range with one another, for example (a) when the particular computing device itself loses contact with one of the other computing devices in the set, or (b) when the particular computing device receives a notification from one of the other computing devices that such other computing device has lost contact with a computing device that the other computing device had been in contact with. The connection table data is then used to locate a lost computing device, or the identity of a device that has such information in its connection table.