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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)                 9  TCP/IP Domain Name System (DNS)                      9  DNS Name Space, Architecture and Terminology

DNS Name Space, Architecture and Terminology 1 2 3 DNS Structural Elements and Terminology: Domains, Subdomains, and Nodes; Roots, Leaves and Branches; Parents, Children and Siblings

The Benefits of the DNS Hierarchical Name Architecture

Like a directory structure, the DNS hierarchical name architecture allows names to be organized from most general to most specific. It also has complete flexibility, allowing us to arrange the structure in any way that we want. For example, we could make a name system that is structured exactly paralleling the geopolitical organization chart I described earlier. We could have the root of the name structure represent the “United Nations”, and create a domain for each country. Then for those countries that have states, like the United States, we could create “state domains” within those countries. Smaller countries not needing those domains could have “city domains” directly under the country domain. The hierarchy is flexible, because at each level it can be given a suitable substructure.

It's important to remember that every standalone internetwork can have its own name space and unique hierarchical structure. Many times, people conflate the idea of “a DNS name space” with “the DNS name space”. The latter refers to the DNS hierarchy used for the global Internet, and it's obvious that this deserves a great deal of attention. But it is just one possible arrangement, if an important one, of an infinite number of possible structures.

In the remaining topics of this section, I continue the generic descriptions of DNS name space and architecture, including a look in the next topic at DNS names and terminology. The section on name registration and authorities provides more specific information on the Internet's DNS hierarchy. As we'll see there, geopolitical structures are in fact used in a manner similar to what I described above to assign names to some of the Internet's computers, but other parts of the hierarchy are different.

DNS Name Space, Architecture and Terminology 1 2 3 DNS Structural Elements and Terminology: Domains, Subdomains, and Nodes; Roots, Leaves and Branches; Parents, Children and Siblings