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  Name System Issues, Concepts and Techniques

Name Spaces and Name Architectures (Flat and Hierarchical) 1 2 Name Resolution Techniques and Functional Elements of A Name Resolution System

It seems obvious that for our name system to be implemented, we need some method of assigning names to each of the devices that will use the system. Just as a name system has a name space that is comparable to an addressing system's address space, it also must implement a set of rules and procedures for assigning names, just as an addressing system assigns addresses. This is called name registration.

In general, name registration encompasses the following concepts and tasks:

• Name Assignment and Guaranteeing Uniqueness: The core task of the name registration process is of course assigning names to devices. Like all identification schemes, a key requirement of name registration is ensuring that each name is unique. Duplicated names cause ambiguity and make consistent name resolution impossible.
  
  
• Central Registration Authority Designation: Ensuring uniqueness of names requires that there be someone “in charge” of the name assignment process. This central registration authority may be a single individual that maintains a file containing names, or an organization that is responsible for the overall name registration process. The authority is also charged with resolving problems and conflicts that may arise in registrations.
  
  
• Registration Authority Delegation: In smaller name systems, the central registration authority may be responsible for the actual registration process for all devices. In larger, hierarchical name systems, having this process centralized is impractical. Instead, the central registration authority will divide the name space and delegate authority for registering names in different parts of it to subordinate organizations. This requires a delegation policy to be developed and implemented.
  
  
• Defining Hierarchical Structure: When a hierarchical name space is used, the central authority is responsible for defining how the structure will look. This in turn dictates how names can be registered in different parts of the hierarchy, and of course, also impacts how authority is delegated.

The complexity of the name registration process depends to a great extent on the size and complexity of the name system as a whole, and in particular the architecture of the name space. In a simple name system using a flat name space, registration is usually accomplished using a single authority. There is no structure, of course, and usually no delegation of authority, so there isn't much to registration.

For hierarchical name systems, name registration is tied tightly to the hierarchy used for names. The central authority defines the structure of the hierarchy, and decides how the hierarchy is to be partitioned into subsets that can be independently administered by other authorities. Those authorities may in turn delegate subsets of their name spaces as well, creating a flexible and extensible system.

This ability to delegate authority for name registration is one of the most powerful benefits of a hierarchical name space. For example, in the TCP/IP Domain Name System, a central authority is responsible for name registration as a whole; it is in charge of deciding what top-level domains, such as “.com”, “.edu”, “.info” and “.uk” are allowed to exist. Authority for managing each of these subsets of the worldwide hierarchy is then delegated to other organizations. These organizations continue the process of dividing the hierarchy as they see fit. Eventually each organization is able to decide how it will name its own internal systems independently; for example, IBM can register names in any way it sees fit within the “ibm.com” name.

Name Spaces and Name Architectures (Flat and Hierarchical) 1 2 Name Resolution Techniques and Functional Elements of A Name Resolution System