Name servers are system processes that maintain databases of information about objects existing in computer networks, and answer user queries concerning them. Naming services are becoming increasingly important as computers are connected into networks and eventually into internetworks. This report describes our design and implementation of the DARPA Internet name servers in the Berkeley Unix environment. The naming service and the information it provides are both distributed and replicated. user update queries, as well as retrieval queries, were implemented, and zones of network information are kept up to date by incremental zone refresh operations.