DNS (Domain Name System)

DNS stands for Domain Name System. It is an application layer protocol that provides a mapping between a host's name on the network and its numerical IP address.

Importance of DNS:

• DNS allows users to use user-friendly names (like ftp.EduSoft.com) instead of remembering numerical IP addresses (like 132.147.165.50).
• It is essential for the functioning of the internet, as it translates domain names into IP addresses, allowing for easier navigation across the web.

Types of Domain Names:

1. Generic Domains:

   • Defines registered hosts by their generic behavior (e.g., .com, .org).
   • Uses three-character labels to describe the organization type.

2. Country Domain:

   • Follows the same format as generic domains but uses two-character country codes (e.g., us for the United States).

3. Inverse Domain:

   • Used for mapping an address to a name. For security purposes, the DNS server checks if the client is authorized by mapping the address back to a domain name.

Working of DNS:

• DNS operates on a client/server model:

  • DNS Clients send requests to DNS servers.
  • DNS Servers respond with the corresponding information.

  DNS Lookups:

  • Forward DNS Lookup: A request where the client sends a domain name to get the corresponding IP address.
  • Reverse DNS Lookup: A request where the client sends an IP address to get the associated domain name.

• DNS uses a distributed database to store host names and IP addresses. When a DNS server doesn't have the IP address for a given hostname, it forwards the request to another DNS server.

How DNS Works:

1. A DNS resolver receives a hostname request from the client (e.g., a web browser).
2. The resolver queries the DNS server for the IP address of the hostname.
3. If the DNS server doesn’t have the IP address, it forwards the request to another DNS server.
4. The resolver receives the IP address and completes the request, allowing the client to connect to the host.