The Domain Name System Hierarchy. This hierarchy has multiple levels from 0 to 127 with a root at the top. The domain hierarchy is read from right to left with each section denoting a subdivision.
Domain Names are hierarchical and each part of a domain name is referred to as either the root top level second level or as a sub-domain. All resolvers treat dots as separators between the parts of the domain name. The Domain Name System DNS has a hierarchical inverted tree structure.
The domain hierarchy is read from right to left with each section denoting a subdivision.
In the Domain Name structure computer IP address mappings equivalent to files are placed in domains and these domains can contain other domains sub domains. The domain hierarchy that is shown in the following figure is a leaf of the huge DNS namespace supported on the global Internet. DNS is a big hierarchically distributed system where domain name service is maintained and operated by hundreds of independent authoritative operators and network of thousands of server computers. These top-level domains TLD became known as domain name extensions and represent the highest level in the Domain Name System hierarchy.