1. A method of selecting a content source for an application from a plurality of potential content sources, comprising: maintaining a mapping between a network resource and a static URL to be accessed by an application when updating, over an electronic network, content used in the application; receiving, at the network resource, a configuration request providing the static URL; receiving, at the network resource, program information that at least identifies the application and version of the application; determining a second URL based on the received information that is specific to the identified application version and from which content specific for that application version can be obtained; and providing the second URL to the application in response to the request.