The 411 system uses a Rocks RPC service called channeld to communicate with client nodes. The client nodes run the RPC service, and the frontend has a RPC client which sends out alerts on its multicast channel. When the clients receive a 411-alert RPC message, along with the name of the file that changed, it does a pull of the file using 411get.
411 is akin to a distributed database, and is not a centralized lookup service like NIS. While scalable, 411 does not provide instantaneous distribution of new files. The delay between running the 411 makefile and all nodes receiving the changed file depends on cluster size. A large password file on a cluster with many nodes can take up to a minute to fully synchronize on all nodes.