Embodiments of the present disclosure provide methods, apparatus and computer program products for service discovery. A method implemented at a primary Network-Function Repository Function, NRF, in a communication network, wherein the communication network comprising at least one primary NRF and at least one secondary NRFs, the method comprising: receiving a discovery request from a first secondary NRF, wherein the discovery request comprises a service query information for a target Network Function, NF, obtaining target NF information, providing the target NF information to the first secondary NRF.