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What is DNS?


DNS stands for Domain Name System, it’s a hierarchical naming model in networking which converts the domain name such as www.spiralcomputing.com, www.google.com, into Internet Protocol (IP) addresses such as: 172.16.0.5.

It can be called as the phonebook of internet. When an user accesses information online through domain names, the web browsers interact through IP addresses and DNS translates domain names to IP addresses so browsers can load the Internet resources.

Every device that is connected to the Internet has an unique IP address which other machines use to find that device. DNS servers eradicates the need for users to memorize IP addresses such as 192.168.2.1 (in IPv4), or more complex (newer way) alphanumeric IP addresses such as 2402:cb00:2046:2::c739:d9a3 (in IPv6)


How does DNS works after all?


The process of DNS resolution involves translating the hostname (such as www.example123.com) into a computer-friendly IP address (such as 192.168.1.1). An IP address is given to each device on the Internet which is like a street address which is used to find a particular home. When a user wants to load a webpage, a translation must occur between what a user types into their web browser (example123.com) and the machine-friendly address necessary to locate the example.com webpage.

Note: Here we will use the library system to facilitate how DNS works.

DNS Servers can also be programmed by JAVA, for which you need to check How to program DNS Server by using UDP Sockets


There are 4 DNS servers involved for DNS resolution, such as:


DNS Recursor: Here, the recursor server can be thought  as a librarian who is asked to go find a particular book somewhere in a library. The DNS recursor is a server which is designed to receive queries from client machines through applications like web browsers.

Root Name Server: The root server is the first step in translating (resolving) host names into IP addresses. It can be thought as an index in the library that points to different shelf of books - typically it serves as a reference to other more specific locations.

TLD Name Server: TLD means top-level domains, such as .com or .in extensions. The TLD servers can be thought as a specific shelf of books in a library where it will find some specific IP addresses which has domain name extension like .com or .in.

Authoritative Name Server: The authoritative name server can be thought as a dictionary on a rack of books, in which a specific domain name can be translated into its IP address. The authoritative name server is the end in the name server query. Finally the authoritative name server will access the requested record and it will return the IP address for the requested hostname back to the DNS Recursor (the librarian) that made the initial request.

The picture below clearly describes how does DNS works,

dns full form, dns server
DNS Server


2 comments:

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    ReplyDelete
  2. Hi there,

    Thank you for clearing up my concept on DNS.


    You are literally awesome! !! Your explanations are exactly
    what an interviewer want. everything is explained in detail
    and easy to understand. Happy Learning! Thanks a lot. Good day man

    Best Regards,

    www.hellodraweasy.com

    ReplyDelete

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