Fiber network for interrogating fiber-optic sensors in a first Passive Optical Network (PON) and in a second PON, the fiber network comprising a test signal transceiver for emitting query signals and for receiving response signals, a first PON and a second PON. Each PON comprises a light source for generating telecommunication signals and a fiber-optic sensor. Each PON can transmit the telecommunication signals to a plurality of subscribers, and is optically connected to the test signal transceiver such that the query signals can be fed into the respective PON and propagate in the PON to the fiber-optic sensor, and such that the test signal transceiver can receive response signals from the fiber-optic sensor through the PON. The fiber network further comprises a query signal splitter, optically connected to the test signal transceiver and to the PONs such that it can feed a query signal into the PONs simultaneously, and such that it can feed response signals from the PONs into the test signal transceiver.