Methods and apparatus for addressing of Virtual Network Functions, VNFs. A registration controller of a VNF instance controls a transmitter to transmit a registration request to a VNF Service Registry, VNF-SR, the registration request identifying a public address of the VNF instance. A receiver of the VNF-SR receives the registration request and a VNF address determiner determines a VNF address for the VNF instance based on the received registration request. A Database Management System, DBMS, stores the determined VNF address in a memory. An event subscriber of a Virtual Network Function Manager, VNFM, controls a transmitter to transmit a subscription request to the VNF-SR, the subscription request comprising an identifier for a VNF. A receiver of a Virtual Configuration Server, VCS, receives a notification from the VNF-SR when a change has occurred in configuration and/or address data stored in the memory of the VNF-SR and relating to one or more VNF instances. A configuration manager determines a configuration instruction for the one or more VNFs based on the received notification, and controls a transmitter to transmit the configuration instruction to the one or more VNF instances.