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The TCP/IP Guide  9  TCP/IP Application Layer Protocols, Services and Applications (OSI Layers 5, 6 and 7)       9  TCP/IP Key Applications and Application Protocols            9  TCP/IP File and Message Transfer Applications and Protocols (FTP, TFTP, Electronic Mail, USENET, HTTP/WWW, Gopher)                 9  Usenet (Network News) and the TCP/IP Network News Transfer Protocol (NNTP)                      9  Usenet Overview, Concepts and General Operation

Usenet Communication Model: Message Composition, Posting, Storage, Propagation and Access 1 2 3 4 Usenet Message Format and Special Headers

As the previous topic mentioned, a key concept in Usenet communication is the newsgroup. Newsgroups are in fact the addressing mechanism for Usenet, and sending a Usenet article to a newsgroup is equivalent to sending e-mail to an electronic mail address. Newsgroups are analogous to other group communication venues such as mailing lists, chat rooms, Internet Relay Chat channels or BBS forums—though calling a newsgroup a “list”, “room”, “channel” or “BBS” is likely to elicit a negative reaction from Usenet old-timers.

Like any addressing mechanism, newsgroups must be uniquely identifiable. Each newsgroup has a newsgroup name that describes what the topic of the newsgroup is about, and differentiates it from other newsgroups. Since there are many thousands of different newsgroups, they are arranged into sets called hierarchies. Each hierarchy contains a tree structure of related newsgroups.

The total collection of newsgroup hierarchies is in many ways similar to the domain name tree structure used in DNS. Each Usenet hierarchy is like a collection of all the domain names within a DNS top-level domain. Just as a domain name like www.pcguide.com is formed by appending the label of the top level domain “com” to the second-level domain name “pcguide” and the subdomain “www”, newsgroup names are created in the same way. They are created from a top-level newsgroup hierarchy name, to which are attached a set of descriptive label that describe the newsgroup's place in the hierarchy.

One difference between DNS and Usenet hierarchies is that while DNS names are created from right to left as you go “down the tree”, Usenet newsgroup names are formed in the more “natural” (for English speakers) left to right order. For example, one of the main Usenet hierarchies is the “comp” hierarchy, devoted to computer topics. Within “comp” is a sub-hierarchy on data communications called “dcom”, and within that a group that discusses data cabling. This group is called comp.dcom.cabling. Almost all newsgroups are structured in this manner.

Usenet Communication Model: Message Composition, Posting, Storage, Propagation and Access 1 2 3 4 Usenet Message Format and Special Headers