Today, Usenet has grown to enormous proportions. Sites that carry the whole of netnews usually transfer something like a paltry sixty megabytes a day. Of course this requires much more than pushing around files. So let's take a look at the way most systems handle Usenet news.
News is distributed through the net by various transports.
The historical medium used to be UUCP, but today the main traffic is carried by Internet sites. Any article generated or received by the local news system is forwarded to them, unless it has already been seen at that site, in which case it is discarded. This header contains a list of all systems the article has been forwarded by in bang path notation. On the other hand, the newsgroups exchanged may be limited by both the sending or receiving system. The set of newsgroups and distributions allowed for transmission to a site are usually kept in the sys file.