Please Whitelist This Site?

I know everyone hates ads. But please understand that I am providing premium content for free that takes hundreds of hours of time to research and write. I don't want to go to a pay-only model like some sites, but when more and more people block ads, I end up working for free. And I have a family to support, just like you. :)

If you like The TCP/IP Guide, please consider the download version. It's priced very economically and you can read all of it in a convenient format without ads.

If you want to use this site for free, I'd be grateful if you could add the site to the whitelist for Adblock. To do so, just open the Adblock menu and select "Disable on tcpipguide.com". Or go to the Tools menu and select "Adblock Plus Preferences...". Then click "Add Filter..." at the bottom, and add this string: "@@||tcpipguide.com^$document". Then just click OK.

Thanks for your understanding!

Sincerely, Charles Kozierok
Author and Publisher, The TCP/IP Guide


NOTE: Using software to mass-download the site degrades the server and is prohibited.
If you want to read The TCP/IP Guide offline, please consider licensing it. Thank you.

The Book is Here... and Now On Sale!

Searchable, convenient, complete TCP/IP information.
The TCP/IP Guide

Custom Search







Table Of Contents  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  TCP/IP Network News Transfer Protocol (NNTP)

Previous Topic/Section
NNTP Overview and General Operation
Previous Page
Pages in Current Topic/Section
1
2
34
Next Page
NNTP Client-Server Communication Process: News Posting and Access
Next Topic/Section

NNTP Inter-Server Communication Process: News Article Propagation
(Page 2 of 4)

Basic NNTP Propagation Methods

Now let's look at how messages are actually propagated between servers using NNTP. There are two techniques by which this can be done:

  • “Pushing” News: In the push model, as soon as a server receives a new message, it immediately tells its upstream and downstream neighbors about the message and asks them if they want a copy of it.

  • “Pulling” News: In the pull model, servers do not offer new articles to their neighbors. The neighboring servers must ask for a list of new messages if they want to see what has arrived since the last connection was established, and then request that the new messages be sent to them.

There are advantages and disadvantages to both of these techniques, but pushing is the model most commonly used today.

Key Concept: One important role that NNTP plays is its propagation of articles between Usenet servers, which is what makes the entire system possible. Two models are used for article propagation: the push model, in which a server that receives a new message offers it to connected servers immediately, and the pull model, where servers that receive new messages hold them until they are requested by other servers. The push model is usually preferred since it allows for quicker communication of messages around the system.



Previous Topic/Section
NNTP Overview and General Operation
Previous Page
Pages in Current Topic/Section
1
2
34
Next Page
NNTP Client-Server Communication Process: News Posting and Access
Next Topic/Section

If you find The TCP/IP Guide useful, please consider making a small Paypal donation to help the site, using one of the buttons below. You can also donate a custom amount using the far right button (not less than $1 please, or PayPal gets most/all of your money!) In lieu of a larger donation, you may wish to consider purchasing a download license of The TCP/IP Guide. Thanks for your support!
Donate $2
Donate $5
Donate $10
Donate $20
Donate $30
Donate: $



Home - Table Of Contents - Contact Us

The TCP/IP Guide (http://www.TCPIPGuide.com)
Version 3.0 - Version Date: September 20, 2005

© Copyright 2001-2005 Charles M. Kozierok. All Rights Reserved.
Not responsible for any loss resulting from the use of this site.