Question

What is domain name space? Explain.

Answer 1

1. Domain name space was designed to achieve hierarchical name space.
2. In this, the names are represented as a tree like structure with a root element on the top and this tree can have a maximum of 128 levels starting from root element taking the level 0 to level 127.
   
   Domain Name Space
3. The domain name space where the root element is present at the top most level i.e., level 0.
4. The root element always represents the NULL string (empty string).
5. The next level to the root element is node (children of root element). Each node in the tree has a label and a domain name.

• Label:

1. It is a string which can have maximum of 63 characters.
2. Each node in that level should have different labels thereby assuring the individuality of the domain name.
3. In other words, Labels are the names given to domains.
4. Domain is a sub tree in domain name space tree structure. The domain can be further divided into sub domains.
   
   Domain Name and Label

• Domain name-

1. It is the sequence of labels. In domain name the sequence of labels are separated by dot (.).
2. The domain name is always read from the lower level to the higher level i.e., from the leaf node to the root node.
3. Since the root node always represents NULL string, all the domain name ending with a dot.

• Basic rules of Domain names-

1. Domain can consists of Alphabets a through z, and the digits 0 through 9.

1. Hyphens are allowed, but hyphens cannot be used as first character of a domain name.
2. Spaces are not allowed
3. Special symbols (such as !, $, &,. not permitted