Network News Transfer Protocol (NNTP) defines two types of feeds: pull and push/accept. With a pull feed, a server connects to the ISP's NNTP server and pulls down the articles from the groups that it wants. With a pull feed, your NNTP server behaves like a newsreader client retrieving any new unread articles. The connection is unidirectional, so to send articles that your users generate, your server establishes a second connection to upload your users' posts. Like a pull feed, the push/accept feed is unidirectional and defines what to send and accept when articles are transmitted. This feed is more complex to configure because it requires several definitions on both sides of the connection. The ISP configures a push feed that determines which articles to send to your server. On your side, you configure an accept feed that matches the ISP's configuration for which groups it will send.
If the group specifications for the two parts of the feed don't match, any mismatched groups will be ignored. For example, if the ISP's push feed defined that you would receive groups A, B, C, and D, but your accept feed specified groups A, B, and C, your server will reject the transmission of the D newsgroup articles. From your perspective, this type of push/accept feed configuration is an inbound feed. Because a feed is unidirectional, push/accept configurations require the definition of an outbound feed where your server specifies the groups to push and your ISP defines the groups to accept. Not only do the groups defined in the push portion and accept portion of the outbound feed need to match, but you must ensure that the same groups are defined in the outbound and inbound feed definitions so that your users' article postings will be uploaded. Because the push/accept feeds offers more control options for governing sending and receiving articles, it is generally the preferred feed type.
