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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)

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TCP/IP Host Table Name System
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DNS Overview, Functions and Characteristics
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TCP/IP Domain Name System (DNS)

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.

Background Information: I assume in this section that you are already familiar with the basics of name systems, and make reference to appropriate topics in the name system overview as needed. You should also be familiar with how TCP/IP host tables work, as described in the topic preceding this section.


Note: Now, for a quick terminology note. First, even though the abbreviation “DNS” usually stands for “Domain Name System”, you will also sometimes see the “S” stand for other words, especially “Service” or “Server”. Second, some documents refer to this name system as “the DNS”. Most people just say “DNS” without the definite article, and that's the convention I follow here as well.


Quick navigation to subsections and regular topics in this section



Previous Topic/Section
TCP/IP Host Table Name System
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DNS Overview, Functions and Characteristics
Next Topic/Section

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