There are three types of Name Servers which control the entire.
Domain Name System:
1. Root Name Server - top-level server which contains entire DNS tree, maintained by ICANN. There are 13 servers.
2. Primary / Master Name Server - contains zone resource records. These records are updatable by domain name holders such as organizations.
3. Secondary / Slave Name Server - contains a copy of primary server files. This server has no authority to update, but reduce the workload of the master server by sharing the queries.

Every zone has the server which contains a database called zone file.

Each node in the DNS tree-like structure has a name, called a label. Label is a string having a maximum of 63 characters.

A server can contain more than one zone files (Zones).

Domain Name space is an entire collection Domains, Sub domains and Zones

(i) The resolver is a program which is responsible for initiating the translation of a domain name into an IP address.
(ii) Since a resolver is stored in the host. There is no need of any protocol to form a connection between the resolver and the user program.

Zone is a group of contiguous domains and subdomains. If the zone has a single domain, then zone and domain are the same.

(i) www.tn.gov.in
(ii) www.google.com
(iii) www.Quora.com
(iv) www.wikipedia.org

URL (Uniform Resource Locator) is the address of a document on the Internet. URL is made up of four parts: protocols, hostname, folder name and file name. Each part has its own specified functions.

The types of IP address
(i) IPv4 Address and
(ii) IPv6 Address