Note: Many topics at this site are reduced versions of the text in "The Encyclopedia of Networking and Telecommunications." Search results will not be as extensive as a search of the book's CD-ROM.

The NNTP protocol is the delivery mechanism for the USENET newsgroup service. USENET runs on the Internet and other TCP/IP-based networks and provides a way to exchange messages, articles, and bulletins throughout the Internet. Articles are put in central databases throughout the Internet and users access the database to get the articles they need. This reduces network traffic and eliminates the need to store a copy of each article on every subscriber's system.

There are thousands of different newsgroups related to computers, social issues, science, the humanities, recreation, and other topics. See "USENET" for more information on USENET itself. This topic discusses the operation of the NNTP protocol.

USENET servers use NNTP to exchange news articles among themselves. NNTP is also used by clients who need to read news articles on USENET servers. The server-to-server and user-to-server connections are described here:

• Server-to-server exchanges    In the server-to-server exchange, one server either requests the latest articles from another server (pull) or allows the other server to push new articles to it. In either case, both servers engage in a conversation in which specific newsgroup information is requested and then delivered. A primary goal is to prevent the sending system from sending articles that the receiver already has. Select newsgroups and articles can be blocked.


• User-to-server connections    Users run news readers, which are now included with most Web browsers. The user first connects with a newsgroup server (usually located at an ISP (Internet service provider), then downloads a list of available newsgroups. The user can then subscribe to a newsgroup and begin reading articles available in that group or post new articles.

Before NNCP, USENET servers used UUCP (UNIX-to-UNIX Copy Program) to exchange information. UUCP is a "flood broadcast" mechanism. Hosts send new news articles they receive to other hosts, which in turn forward the news on to other hosts that they feed. Usually, a host receives duplicates of articles and must discard those duplicates-a time-consuming process and waste of bandwidth.

NNTP uses an interactive command and response mechanism that lets hosts determine which articles are to be transmitted. A host acting as a client contacts a "server" host using NNTP, and then inquires if any new newsgroups have been created on any of the serving host systems. An administrator can choose to create similar newsgroups on the host he or she manages.

During the same NNTP session, the client requests information about new articles that have arrived in all or some of the newsgroups. The server then sends the client a list of new articles and the client can request transmission of some or all of those articles. The client can refuse to accept articles that it already has.

Readers interested in the details of NNTP commands and responses should read RFC 977 (A Proposed Standard for the Stream-Based Transmission of News, February 1986).

Some organizations may prefer to set up their own USENET systems on their TCP/IP-based intranet rather than deploy groupware and collaborative applications. If you plan on setting up your own news server, refer to "USENET."

Copyright (c) 2001 Tom Sheldon and Big Sur Multimedia.
All rights reserved under Pan American and International copyright conventions.