Domain Name System Explained

DNS Explained

The DNS (Domain Name System) is one of the most significant internet services in existence, without which we wouldn’t be able to access any online content or even send an email. In fact, every time we try to connect to a website or any other online service, DNS root server help our computers find and reach the desired addresses. To acquire information online, humans search through domain names like,; DNS involves translating this into IP addresses for the content to load.

How does DNS Root infra work?

When a user types an address name into the browser, the operating system checks the information in local cache system. If not found, a query seeking to match the domain name with its IP address is send over the Internet to find the website which is often provided by your ISP(Internet Service Provider). The first server the ISP interacts with is the Recursive Resolver which is the first designed to receive queries through applications such as web browser. The recursor will make requests to the website assuming that it already has a response cache and if not it goes through DNS hierarchy in order to satisfy the client’s DNS query. The recursive talks to first type of DNS server called Root Server. It translates the human readable hosts into IP addresses. The top level domain (TLD) server is the next step in the search for a specific IP address, and it hosts the last portion of a hostname (In, the TLD server is “com”). The TLD server will then return the Authoritative Name Server where the desired domain is stored. This is when the server that made the request sends a query to the authoritative server hosting the zone of the domain in question. Once the request has reached the authoritative server, it will respond to the requesting server that is recursive resolver with the IP address for The browser can send request to view the website’s content using the IP address that it received.

DNS Diagram




Types of DNS Queries:

  • Recursive Query:In recursive query, a DNS client provides a name resolution, and the DNS Resolver “must” provide an answer – it either responds with either a relevant answer that is record, or an error message if it can’t be found.
  • Iterative Query:In an iterative query, the name server, will not go and fetch the complete answer for your query, but will give back a referral to other DNS server’s, which might have the answer. This process continues with additional DNS servers down the query chain until either an error or timeout occurs.
  • Non-recursive Query:In this kind of query, DNS resolver already knows the answer. It immediately returns because the answer already exists in the cache. In such cases, a response is immediately returned to the client.

recursive & non recursive query




The whole process of requesting a server might seem complicated, but in real, query resolution take place in a blink of an eye. This is just a step-by-step process which is faster than tenths of second.

DE-CIX India is an Internet Exchange in India that hosts Route Server Peering and DNS Root Servers to improve the DNS queries by its connected networks and helps them to optimize the time required to resolve the DNS queries. There are 13 such DNS root servers available in the world out of which DE-CIX India hosts 4 of them such as PCH, Verisign, RIPE Atlas Probes and K-Root Server. DE-CIX India currently interconnects around 175+ networks and all these networks are able to peer with these DNS root servers through its platform. Reach out to us in case if you wants to peer with these DNS root Servers.

We hope the above blog seems more informative to you and able to value add to your knowledge. Do let us know your feedback / concerns if you think something needs to be corrected or added.


Who Provides Internet Service to Internet Service Providers – ISPs

Who Provides Internet Service to Internet Service Providers – ISPs

You need to understand what an Internet Service Provider is before understanding who offers an internet service to ISPs or internet service providers.

Definition of Internet service provider:

An ISP (Internet service provider) is an organization that offers services for using and accessing the Internet. The structure of internet service providers can take many different forms, including commercial, community-owned, non-profit, or other types of privately owned businesses.

An ISP community is the only industry which helps us in utilizing the benefits of internet and the great opportunities it holds for us. It only requires a modem and router for getting started.

The services provided by the ISP can include,

  1. Internet transit
  2. Internet access
  3. Domain name registration
  4. Collocation
  5. Usenet service

Now the question is who provides the internet to the ISPs?

ISPs provides data connection to their subscribers by virtue of which they can connect smartphones and other gadgets by using Wi-Fi routers available for providing internet. Also, they establish a high bandwidth connection(s) to either an internet exchange, or other ISPs, or as a combination of both. ISPs can also connect directly to (content) service providers or even host their servers directly inside one of their facilities (common with Google, Facebook, Netflix, etc.)

Let’s discuss some common terms used.


Peering is a method that allows two networks to connect and exchange traffic directly without having to pay a third party to carry traffic across the Internet.

In order to acquire the most traffic, two different types of tier networks are typically used, along with peering and bridging. The majority of large businesses choose to set up their own peering connections.

This approach is used by reputable internet service providers. They offered the subscribers access to their own network at the time of ISP peering. The entire processing is free, and neither ISP is paid by the other.

Peering at Internet Exchange Point (IXP

There are two types of Peering, one is public peering and another is private peering.

Peering at Internet Exchange Point (IXP) –

What is Internet Exchange Point (IXP)

Internet Exchange Point is a position where many ISPs interconnect their network together. Probably several peering sessions can be established across a single IXP peering.


Small data providers prefer for IP-transit to operate.

This is typically utilized in situations where the ISP is unable to connect to the outside world.

As a result, IP-transit reaches people that ISPs cannot. In general, it involves transporting internet traffic that exists between continents.

Thus, it can be connected to different types of ISP that is a paid service. The payment of the ISP depends on the amount of traffic attracted by the IP-Transit.

Network Tiers available in the market

       1. Tier 1

It is the huge network intended for offering the internet to ISPs. Therefore, it is a kind of transit free network that is required for peering with every other tier 1.

      2. Tier 2

This kind is required for peering with different type of networks, but still goes for payment settlement in order to reach some segment of the internet.

      3. Tier 3

Tier 3 is a type of network, which purchases the transit from different types of networks in order to reach the internet.

These tiers are available depending on the cost and quality. All the three kinds of tiers are known as the high performance networks.

The major goal of employing these levels is to direct customers toward the preferred providers. The easiest strategy to reduce costs while maintaining the top tier is in this way. These layers are important because they protect customer choice.

Consequently, the networks are perfect for allowing the users to provide the widest types of internet service provider.