NDB defines a protocol for use with relational database systems in a TCP/IP environment. It has the following objectives:

• To allow any workstation/mainframe users and applications to issue SQL statements interactively or imbedded within the application programs, to access any database on any operating system.
• To distribute the applications of a database host to a requester machine.

NDB is built on the Remote Procedure Call (any arbitrary implementation of RPC) using the client/server model. Please see Figure - Components in the Network Database (NDB) Protocol for an overview of the various NDB components.

http://www.pms.ifi.lmu.de/mitarbeiter/ohlbach/multimedia/IT/IBMtutorial/3376c423.html
http://www.mysql.org/doc/refman/5.1/en/mysql-cluster-glossary.html

J'ai trouvé sont utilisation dans Inferno (embeded os), Plan9 (os) et MySql Cluster.

http://ndbserver.rutgers.edu/. The NDB is supported by funds from the National Science Foundation and the Department of Energy.

A Non-Directional Beacon (NDB) is a radio broadcast station in a known location, used as an aviation or marine navigational aid.