A method monitors a data transmission network having a plurality of devices connected to one another over fixedly prescribed signal transmission paths, for anomalies. One of the devices is a master device that has a counter and a trigger apparatus, by which a prescribed signal feature of a signal is acquired, and upon the acquisition, a master counter state corresponding thereto is read. The method provides for an evaluation apparatus to determine, under predetermined conditions, a setpoint value of at least one network-specific parameter defined by a physical property of the network, before an actual value of the network-specific parameter is determined from a difference between the master counter state and a further counter state, and an anomaly is indicated if a predetermined deviation criterion between the actual value and the setpoint value is met.