DNS namespace: DNS is the name service provided by the Internet for TCP/IP networks. DNS is broken up into domains, a logical organization of computers that exist in a larger network. The domains exist at different levels and connect in a hierarchy that resembles the root structure of a tree. Each domain extends from the node above it, beginning at the top with the root-level domain. Under the root-level domain are the top-level domains, under those are the second-level domains, and on down into subdomains. DNS namespace identifies the structure of the domains that combine to form a complete domain name. For example, in the domain name sub.secondary.com, “com” is the top-level domain, “secondary” identifies the secondary domain name (commonly a site hosted by an organization and/or business), and “sub” identifies a subdomain within the larger network. This entire DNS domain structure is called the DNS namespace. The name assigned to a domain or computer relates to its position in the namespace.