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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)

Absolute (Fully-Qualified) and Relative (Partially-Qualified) Domain Name Specifications 1 DNS Hierarchical Authority Structure and the Distributed Name Database

The DNS name space consists of a hierarchy of domains and subdomains. From the root we have a number of top-level domains, then second-level domains below them, and still lower-level domains below that. The obvious questions then become: how do we determine the shape and structure of the name space, and who will manage it? More specifically, who will control the root of the tree and decide what the top-level domains will be called? How will we then subdivide control over the rest of the name space? How do we ensure there are no conflicts in choosing the names of sibling subdomains within a domain?

DNS can be used on private networks controlled by a single organization, and if so, the answer to my questions above is obviously, “that organization”. We'll discuss private naming, but in reality, it's just not that interesting. The vast majority of DNS use occurs on the public Internet. Here, we have a much greater challenge, because we have to construct a name space that spans the globe and covers millions of machines managed by different organizations. For this, we need a very capable name registration process and administration methods to support it.

In this section I describe the process of name registration and how authorities are managed within the Domain Name System, focusing on the public Internet. I begin with a description of the DNS hierarchical authority structure and how it relates to the hierarchical name space, and a discussion of the concepts behind the DNS distributed name database. I describe the Internet's organizational and geopolitical top-level domains, and how they are administered by various authorities. I then discuss how authority is delegated to the second-level and lower-level domains, and how public registration of domain names works, including how public registration issues and problems are resolved. I explain how the DNS name space is partitioned into administrative zones of authority, and conclude with a brief discussion of private DNS name registration.

Absolute (Fully-Qualified) and Relative (Partially-Qualified) Domain Name Specifications 1 DNS Hierarchical Authority Structure and the Distributed Name Database