A simple solution for service scaling is to have the clients know about the protocol used for service replication. When a new service is deployed, the load balancing protocol can be hard-wired into the client programs. A well-known example is the hidden mirroring in the Netscape browser, which detects requests to the netscape.com server and maps them to requests to a range of servers (www1.netscape.com to www32.netscape.com). Similar approaches can be taken for clients of other services. A more general approach is to download client programs from the server site in form of applets and to equip them with the appropriate protocol for load balancing and the contingency plans for server failures. Such an approach is taken in [27]. For many applications, in particular data dissemination, intelligent clients alone are of little benefit. We described earlier the problems caused to Web caches by mirroring, of which Netscape's hidden mirroring is a special case. This is an example where intelligent clients may actually undermine network-wide efforts for service scaling.