A mechanism to ensure that the same server/proxy is selected by different server/proxy discovery mechanisms executed in a network control element and a terminal equipment, respectively. A first selection of a server/proxy is executed by a network control element on the basis of a first discovery procedure. Then, a second selection of a server/proxy is started by a terminal equipment on the basis of a second discovery procedure. A relay agent element is used for responding to the request on behalf of a configuration server or for modifying a configuration server response so that the same server/proxy is selected by the network control element and the terminal equipment.