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 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)

TCP/IP Host Table Name System 1 DNS Overview, Functions and Characteristics

The creation of host tables to map computer names to addresses greatly improved the usability of the early Internet and the TCP/IP protocol suite that implemented it. Unfortunately, while the host table name system worked well when the internetwork was small, it did not scale particularly well as the Internet started to grow in size and complexity. The name system had to stay but the use of host tables had to be dispensed with in favor of a newer, more capable system.

Over the period of several years, many engineers worked to create a system that would meet not just the needs of TCP/IP internetworks of the time, but also of the future. The new name system was based on a hierarchical division of the network into groups and subgroups, with names reflecting this structure. It was designed to store data in a distributed fashion to facilitate decentralized control and efficient operation, and included flexible and extensible mechanisms for name registration and resolution. This new name system for TCP/IP was called the Domain Name System (DNS).

In this section I describe the concepts behind TCP's Domain Name System, as well as its operation. The section is divided into four subsections. The first provides and overview of DNS, including a description of its characteristics and components. The next three subsections describe how DNS implements each of the three primary name system functions: the DNS name space and architecture; the DNS name registration process, including hierarchical authorities and administration; and the DNS name resolution process, focusing on how name servers and resolvers work. Finally, I have a topic that briefly highlights the changes made to DNS to support the new version 6 of the Internet Protocol, and its much longer addresses.

TCP/IP Host Table Name System 1 DNS Overview, Functions and Characteristics