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What is DNS? Basics and Types of Servers and Queries

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It is common knowledge that the computer language differs from the languages humans use. While we use domain names like “example.com” to identify websites, computers use IP addresses composed of numbers. Imagine how tough it would be for humans to memorize numbers such as 192.158.1.389 as each website has a unique ID, so we would have to remember hundreds of number combinations like this.

Hence, words must be translated into numbers so the system can read and understand them. This is what DNS is for.

What is DNS?

DNS stands for Domain Name System. It can be understood as the “phonebook of the internet”. DNS is the system that helps to map the name of a host website to its numerical address on the internet. It is a database where the domain names are translated into IP addresses and are stored.

DNS is very useful as it makes the task of remembering domain names easy for humans. Browsing on the internet mainly relies on DNS - it acts as the bridge between users and web hosts. Every time a user makes a request, known as a query, to access a particular domain, a DNS server translates it to enable the user to access the website.

A Brief History of DNS

In the 1970s, during the infant stages of the internet, host servers were easy to maintain in a single place, but things went out of hand soon. In 1983, the Domain name System was created to make the internet more efficient and organized.

Since the 1980s, DNS has been evolving along with the complex evolution of computers and the internet. Today, it is impossible to think of web browsing without thinking of DNS - the system has evolved to be a hierarchical, decentralized structure that can help clients access what they want in mere seconds.

Read More on Reddit about DNS 

How does DNS Work?

To understand the workings of a DNS, we need to first understand the different components of the system and how they work. Here are the four main servers involved with a Domain Name System:

DNS Recursor

The DNS recursor is the server that receives the data from the client side. This is where the information goes when you type in a domain name on the search bar. The server receives the client’s query so the DNS request can be satisfied through browsers. From here, the query is passed to three servers for the IP address that needs to be located.

Root Nameserver

The decoding process begins through the root server. Once the query is received by the recursor, the root server points it to more specific locations where the code can be translated into an IP address.

TLD Nameserver

TLD expands to Top Level Domain - this server helps in searching for more specific IP addresses. It hosts the top-level domains like .com, .org, .net, etc. When the IP address cannot be placed by this server as well, it is directed to the final server.

Authoritative Nameserver

This is the last stop where the query can be translated into an IP. The authoritative server is the final authority on finding the requested record. Once the information is placed, the server returns the IP address to the initial client who made the request.

The magic of DNS is that this entire process takes place in seconds - the user cannot perceive how fast the process is done. DNS servers find IP addresses from both inside and outside of their domains.

Types of DNS Queries

During the entire process of a DNS system requesting and returning an IP address query, 3 main types of queries take place:

Recursive DNS Queries

This is the type of query where the server searches for information requested by the client and returns it back to them. This type of query exchange takes place between the recursive server and the person who made the request. A recursive query could answer by giving the right address or producing an error message. 

Iterative DNS Queries

Iterative queries can either be an answer or a referral to a more specific server that can fetch information. This type of query happens between a recursive resolver and the other servers like TLD, root, or authoritative ones. A recursive resolver is a local DNS, while the other servers are non-local. It is not necessary for an iterative query to fetch the address - it usually refers the client to the other servers.

Nonrecursive Queries 

For a nonrecursive query, the recursive resolver knows where to fetch the right address. This can be either of these options - the result is cached on the resolver or the local server directly contacts the authoritative server for the address. It is called a nonrecursive query because the process ends with this query. There are no more queries involved in retrieving the necessary information.

Why is DNS Important?

  • Simply put, DNS helps you connect to all the websites on the internet.
     
  • Not only does DNS enable connection with websites, but it also ensures that this is done smoothly and as quickly as possible.
     
  • DNS makes the internet user-friendly for everyone. It also improves the security of a website.
     
  • DNS is versatile - it is compatible with multiple search engines and evolving technologies.
     
  • Businesses and organizations often benefit from DNS, as the system allows changes.

Summing It Up

The Domain Name System acts as the bridge between the user and the internet - it translates the query entered by the user to return with the IP address and the corresponding website. This process is done by the DNS through a set of servers that process different types of queries or requests. The entire DNS process is completed within seconds. DNS acts as the backbone of the internet - without the system, we will not be able to access websites quickly and safely.

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https://devopsden.io/article/what-is-route-53

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