What is DNS?
On the internet computers identify each other’s with unique numbers called IP addresses, computers do not understand human languages, then how will they load a website when we search for it in the web browser? That’s where DNS comes in. DNS translates the domain name (ex: facebook.com) to an IP address for computers (Domain Name System) maintains IP tables where website domain names are mapped to their IP addresses.
How DNS works internally?
DNS servers work together to provide IP address of the requested website to the web browser, now what are these DNS servers, there are four types of DNS servers
DNS recursive resolver/DNS resolver is provided by internet service provider, it connects the web browser of our computer with DNS name servers
Root name server there are 13 sets of root name servers logically named as letter.root-servers.net where letter ranges from ‘a’ to ‘m’ and these are operated by 12 different organizations each set has a number of servers placed around the world, and it gives the gives the details of appropriate Top-Level Domain (TLD) server based on the extension(.com/.in/.org)
Top Level Domain / TLD name server stores the information of all domain names sharing a common domain extension for example .com TLD name server stores information of all websites ending with .com extension.
Authoritative name server stores the most up to date information of domains and their associated IP addresses.
Let’s understand DNS with below scenario
Suppose you are typing facebook.com in the web browser as the web browser needs IP address it forwards the query to computer OS , operating systems are configured to forward the query to DNS resolver , Now DNS resolver will check whether it has the IP address of the requested website is stored in its cache memory, if not DNS query is forwarded to the root name servers ,root name servers checks the extension of the website whether it is .com .net .org etc based on the extension the root name server provides the IP address of TLD name server to the DNS resolver then the DNS resolver contacts “.com” TLD name server which then provides the IP address of authoritative name server which should necessarily store the IP address of the requested website, finally the authoritative name server provides the exact IP address of the requested website to the DNS resolver, DNS resolver stores this information in its cache for future use and provides the IP address to the computer operating system , OS then forwards it to the web browser , now web browser contacts the Facebook server and loads the requested website that is facebook.com.
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This blog is written by Checkmate Global Technologies, cloud engineering team. Please reach out to them if you have any production issue to be discussed. We will be glad to assist you.
