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The DNS Hierarchy

The DNS Namespace is based on a "tree" structure, with a small(ish) number of generic Top Level Domains (eg, .com, .edu, .org) and a large number of country-based domains (eg .au, .my, .uk). Each TLD supports a group of "second-level" domains, and so on, all the way down to individual hosts.
DNS namespace
  1. A domain name is a dotted sequence describing a path through the name hierarchy from the root, maybe with a trailing dot, thus: bindi.bendigo.latrobe.edu.au.
  2. An individual name component must be less than 63 characters, must begin with a letter, etc...
  3. Upper and lowercase may be used, although name lookups are case insensitive by definition.

 

 
Lecture 9: The Domain Name System (DNS) Copyright © 2002 P.Scott, La Trobe University Bendigo.

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