The Role Of DNS

DNS (Domain Name System)

Computers communicate with other computers (i.e. Servers) through a number label called IP(Internet Protocol) Address. Each device connected to the Internet is known by its IP addresses and IP addresses are generated from DNS.

What is DNS?

DNS is the address book of the Internet which translates a simple web name we type into our browsers to its specific server IP addresses.

DNS is one application layer protocol that facilitates message exchange between Clients and Servers. For seamless communication, both ends should know each other's IP addresses.

Need Of DNS

Each device connected to the Internet has a unique IP address and DNS removes the need to remember all these IP addresses.

Overview

Source: https://media.geeksforgeeks.org/wp-content/uploads/20200822065029/UntitledDiagram.png

Working Of DNS

They are four servers that work together to deliver an IP address to the client(browser) for the requested query.

They are

1. DNS Resolver
2. Root Name Servers
3. TLD Name Servers
4. Authoritative Name Servers

Source: https://media.istockphoto.com/photos/domain-name-system-drawing-on-whiteboard-picture-id182759904?s=612x612

• DNS Server interacts with the other three servers and hunts down the correct IP address then an HTTP request for the requested IP is made to the web server. In this quest, the DNS Resolver itself act as a client for the other three servers
• Root Name Server hunts the information of the top-level domain requested by the client. The root name server routes the local DNS Server to the TLD server based on the domain's extension, which can be .com, .in, .org and many others. They are 13 root servers all around the world which includes the global list of top-level domains in its root zone. There are multiple copies of each one all over the world which use the Anycast routing to provide speedy requests. The root zone contains Generic top-level domains such as .com and .net and.org Country code top-level domains such as .in for India

Source: https://www.netnod.se/sites/default/files/styles/banner/public/2018-06/ROOT%20%281%29.png?itok=Qmc-T9fk

• The Top-Level Domain Server maintains information for all the domain names which share common domain extensions such as .com or whatever comes after the last dot in the URL. The root zone contains Generic top-level domains such as .com, and .net and.org Country-code top-level domains such as .in for India
• The authoritative Name server is the last server involved in a specific domain IP address quest. The local DNS server is provided with the IP address of the requested server found in the DNS A record, or on the CNAME record

After receiving the IP address, the HTTP request and response cycle are established between the client (browser) and the server.

References

1. https://www.cloudflare.com/en-in/learning/dns/what-is-dns/
2. https://youtu.be/DO7YFq4uSGY

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