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!

Get The TCP/IP Guide for your own computer.
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  Name Systems and TCP/IP Name Registration and Name Resolution
           9  TCP/IP Name Systems: Host Tables and Domain Name System (DNS)

Previous Topic/Section
Overview and History of TCP/IP Host Names and Name Systems
Previous Page
Pages in Current Topic/Section
123
4
Next Page
TCP/IP Domain Name System (DNS)
Next Topic/Section

TCP/IP Host Table Name System
(Page 4 of 4)

Use of the Host Table Name System In Modern Networking

That said, the host table name system has not gone away entirely. There are two circumstances in which this technique is still of value:

  • Small “Island” Networks: If you are setting up a small local area network using TCP/IP, and you don't need the names of your devices to be accessible by those outside your network, then guess what? You have the equivalent, of sorts, of the early Internet, and the host table system is as applicable to you as it was to the Internet in the 1970s. You can simply set up host tables on each device and manage them manually. As long as the LAN is small enough that editing these files periodically is not a hassle, this is actually a fast and effective name system, because no exchange of messages is needed for resolution. You can even maintain a master file on one machine and copy it to the others when changes are required using a script, to save time.

  • Providing Local Name Mappings To Supplement DNS: Even though modern systems use DNS for most name resolution, they also usually still support the use of host table files. You can manually enter common name mappings into this file, even for devices that are on the global Internet. Your system can then be set up to consult this list before making use of its assigned DNS server.

The use of the HOSTS file in conjunction with DNS allows you to manually specify mappings for commonly-accessed sites, which may provide a slight performance improvement since there is no need to access a server. Since the HOSTS file doesn't enforce any particular structure to names, it is naturally quite possible to put DNS-style hierarchical names into the file, as I showed in Table 161. The file is loaded into memory and used to override the normal DNS process for names listed in it.

Of course, you then subject yourself to all the potential maintenance headaches of manually-edited files: you must update these files as host names or addresses are changed in the DNS system. For this reason, this second use of the HOSTS file for Internet sites served by DNS is less popular than the use of the file for local machines.

Key Concept: Even though the host table name system is not the primary mechanism used for TCP/IP naming, it still used in two circumstances. The first is to implement a basic name system in a small local TCP/IP internetwork.The second is as an adjunct to DNS, where it allows manual mappings to be created that override the DNS process when needed.


 


Previous Topic/Section
Overview and History of TCP/IP Host Names and Name Systems
Previous Page
Pages in Current Topic/Section
123
4
Next Page
TCP/IP Domain Name System (DNS)
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.