First steps in understanding the Domain Name System

Domain Name System -What does it mean?

The Domain Name System, or just DNS for short, is a decentralized infrastructure built in a hierarchical way. It provides an easy and simple way for humans to use the Internet as we know it in the present day. In its fundamental grounds, the DNS holds a large database containing each existent pair of a domain name and its related IP address.

For visiting and exploring a particular website, a user has to type in its browser the domain name. So, the long DNS process for getting the needed IP address (IPv4 or IPv6) is triggered. That is necessary because the domain name should be converted into a language that machines understand for achieving successful communication, which is numbers. 

The browser of the user is capable of connecting to the needed website only when the associated IP address of the domain name is discovered.

When we look back at the times when the Domain Name System did not exist yet, things were way more complicated. To reach and explore a particular website, users would have to remember and write the challenging IP addresses, for instance, It was a serious memory test. On the other hand, it is way easier to remember a simple domain name, like 

The Domain Name System allowed both sides, humans, and machines to interact with their suitable language.

Main elements of the Domain Name System

  • DNS authoritative server. This is the primary DNS server. It stores the original zone file for the domain. In addition, it is the one capable of giving an authoritative answer to the DNS query. 
  • DNS recursive server. This server is running in the middle between the user’s browser and the other DNS servers. It has cache memory for storing DNS records for some amount of time. It caches the data when a DNS query is successfully answered that continues until the TTL value of the DNS record expires. The DNS recursive server will perform a new search if the DNS records are not accessible anymore. 
  • DNS record. They are in the form of text lines in the DNS zone file, and each of them has its own individual purpose. One of them, for illustration, is the A record, which points a domain name to its IP address. However, there are many DNS record types.
  • DNS query. The purpose of each query is to find a precise DNS record. The DNS query originates from a device and then jumps from a DNS server to another until one can solve it. 

What is a DNS lookup?

The DNS lookup is a process including broad search, which happens over and over every day.

First, the user has to type the website’s domain name that it wants to visit in the browser. From there, a DNS query is initiated to a recursive DNS server requesting the DNS records for the domain. 

Next, the recursive DNS server is going to check in its cache memory if that information is available there. In case it is these, the DNS query will be resolved. In case it is not there anymore, the recursive DNS server will proceed to the root server. The root is able to give information about the accountable TLD server for that domain. 

Next, the recursive DNS server asks the TLD server to give information about the authoritative nameserver in charge. From there, the recursive server is able to get an authoritative answer with the DNS records and the IP address.

Lastly, the recursive server gives the IP address to the browser, and the browser loads the website. 

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