The DNS namespace is the structure of the domains that combine to form a complete domain name. For example, in the domain name comp.workstation.com, “com” is the top-level domain, “workstation” identifies the secondary domain name (a site hosted by an organization or institution), and “comp” identifies a sub-domain within the larger network. Each computer in an internet DNS domain is identified by its Fully Qualified Domain Name (FQDN) such as “comp.workst.fsu.edu
Example of an Internet used DNS
The top-level domain is burgerking.com; the nodes under the top-level domain are marketing.burgerking.com and sales.burkerking.com. The two sub-domains are both DNS name spaces for marketing and sales nodes. Under marketing.burgerking.com there can be other nodes such as ny.marketing.burgerking.com and atl.marketing.burgerking.com.
Active Directory is Microsoft’s LDAP directory services used primarily in Windows environments. Active Directory is used for authentication, authorization and managing organizational units such as workstations or any other resource located at the workstations.
The top-level domain is the “maincompany” domain. The level below it can be the geographical layer consisting of the “main office”. Under the main office there is the “administrative layer” consisting of the servers, workstations and probably the user accounts. Lastly the bottom-level has several machines under the servers, several workstations and workers who log into the user accounts.