Information processing server, information processing system, and system processing method

[Solution] An information processing server. A transmission signal, transmitted from a signal transmission device attached to a domestic animal and relayed to the information processing server by at least one or more signal relay devices installed to correspond to a rearing region of the domestic animal, includes a transmission device identifier for specifying the signal transmission device and a relay device identifier for specifying the signal relay device, the information processing server including: a control unit configured to determine whether or not the domestic animal stays in a rearing region corresponding to a rearing stage on a basis of the relay device identifier and individual information regarding the domestic animal corresponding to the transmission device identifier; and a notification information generation unit configured to generate notification information for controlling notification in an information terminal on a basis of the determination by the control unit.