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DNS(Domain Name System): The Unsung Hero Behind Every Webpage You Visit

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Kushagra Singh
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17 min read

DNS(Domain Name System): The Unsung Hero Behind Every Webpage You Visit

Table of contents

Introduction

Welcome, to the wonderful world of DNS! Today, we embark on an exciting journey to discover how the internet knows where to find the websites we love. DNS, which stands for Domain Name System, is like the address book of the internet. It helps us find our way to websites using names instead of numbers. Let's dive in and uncover the secrets of DNS in a way that even the youngest minds can understand!

What is DNS?

Imagine the internet is like a big city with lots of buildings and houses. Each building has a unique address called an IP address, which is like a street address for that building. Now, instead of remembering all those long numbers, we have DNS, which is like a magical translator that turns easy-to-remember names into those numbers. DNS serves as a crucial component of internet communication by facilitating the translation between domain names and IP addresses.

DNS has two primary purposes

Name Resolution

Load Distribution

Imagine you want to visit a website called "SuperCoolToys.com" on your computer. To do that, you would normally type "SuperCoolToys.com" in your web browser, right? Well, before your computer can connect to the website, it needs to know the address of the server where the website is located. This is where DNS comes in!

  1. Name Resolution: DNS helps translate the domain name "SuperCoolToys.com" into the IP address of the server that hosts the website. An IP address is like a unique identifier for a computer on the internet. It's a series of numbers that looks something like this: 192.168.0.1. Just like how you need a street address to find a house, your computer needs an IP address to find a server on the internet.

    So, when you type "SuperCoolToys.com" in your web browser and hit Enter, your computer asks a DNS server, "Hey, what's the IP address for SuperCoolToys.com?" The DNS server checks its records and replies, "The IP address for SuperCoolToys.com is 123.45.67.89." Now your computer knows the IP address and can connect to the server that hosts the SuperCoolToys website. It's like your computer getting the right directions to find the website.

  2. Load Distribution: Now let's talk about load distribution using DNS. Imagine the SuperCoolToys website is very popular and gets a lot of visitors every day. To handle all that traffic, the website might have multiple servers working together.

    DNS can help distribute the visitors across these servers to make sure no single server gets overwhelmed. It's like having more than one checkout counter in a store to handle all the customers faster.

    One way DNS does this is through round-robin load balancing. Let's say the SuperCoolToys website has three servers with IP addresses 1.2.3.4, 5.6.7.8, and 9.10.11.12. When you type "SuperCoolToys.com" in your web browser, the DNS server can give you a different IP address each time you visit the website. So, one time it might give you 1.2.3.4, the next time 5.6.7.8, and so on. This way, the visitors are distributed evenly among the servers.

    Another way DNS can distribute load is through geographic load balancing. Let's say the SuperCoolToys website has servers in different parts of the world, like one in the United States, one in Europe, and one in Asia. When you visit the website, the DNS server can look at your location (which it knows based on your IP address) and give you the IP address of the server closest to you. This helps reduce the time it takes for the website to load because the server is physically closer to you.

    So, in summary, DNS helps your computer find the right address of a website (name resolution) and can distribute the visitors across multiple servers (load distribution) to make sure the website works fast and doesn't get overwhelmed.

Hierarchical structure: domains, subdomains, and TLDs

Imagine you want to visit a website called "SuperCoolToys.com". Just like before, you type "SuperCoolToys.com" in your web browser. Now let's understand the hierarchical structure behind it.

  1. Domains: A domain is like the main category or the big umbrella under which websites are organized. It's like a big family that has many members. In our example, "SuperCoolToys.com" is a domain. It represents a specific website and all the pages and content related to it.

  2. Subdomains: Within a domain, you can have subdomains. Subdomains are like smaller groups or divisions within the main family. They are used to organize and separate different sections or functions of a website. For example, "shop.SuperCoolToys.com" and "blog.SuperCoolToys.com" are subdomains of the "SuperCoolToys.com" domain.

Subdomains help keep things organized and make it easier to navigate different parts of a website.

  1. Top-Level Domains (TLDs): At the top level of the domain hierarchy, we have the top-level domains (TLDs). TLDs are like the main branches of the family tree. They are the last part of a domain name, appearing after the final dot. Examples of TLDs are .com, .org, .net, .edu, and .gov.

  • ".com" stands for "commercial" and is commonly used for business websites.

  • ".org" stands for "organization" and is often used by non-profit organizations.

  • ".net" stands for "network" and is sometimes used by internet service providers or network-related websites.

  • ".edu" stands for "education" and is reserved for educational institutions like schools and universities.

  • ".gov" stands for "government" and is used for official government websites.

These TLDs give some information about the type of website you're visiting. For example, if you see ".edu" at the end of a domain name, you know it's related to education.

In summary, domains represent the main category or website, subdomains divide the website into smaller sections, and TLDs indicate the type or category of the website. The hierarchical structure helps organize and identify websites on the internet.

DNS Resolution Process

When you want to visit a website, it's like going on an adventure to find a special place on the internet. But to reach that place, you need to know the address. The DNS resolution process is like using a magical map that helps your computer to find that address. Here's how it works:

  1. Recursive and Iterative Queries:

    When you want to visit a website, your computer asks a helper (DNS resolver) to find the IP address for you. Imagine you have a magic book that knows all the addresses of different places. When you want to find an address, you can either ask someone to find it for you (recursive) or follow hints and clues to find it yourself (iterative).

    Recursive Query:

    Imagine you are trying to find your friend's house in a new neighborhood. In a recursive query scenario, you would ask another person (let's call them a "helper") to find the exact address for you. The helper would take on all the work and make several phone calls to various people to gather the necessary information.

    1. You: "Hey, can you help me find my friend's house?"

    2. Helper: "Sure! Let me take care of it."

    3. Helper starts making calls to different people, asking for directions.

    4. Helper: "Hello, I'm trying to find John's house. Can you help me with the address?"

    5. Person 1: "I'm not sure, but I think he lives on Main Street."

    6. Helper: "Thank you! Let me check with someone else just to be sure."

    7. Helper calls another person.

    8. Person 2: "Yes, John lives on Main Street, number 123. His house is the blue one with a white picket fence."

    9. Helper: "Got it! John's address is 123 Main Street. That's your friend's house."

    10. Helper provides you with the final answer: "John's house is at 123 Main Street."

In this example, the helper (DNS resolver) took on all the work of contacting multiple people (DNS servers) to gather the necessary information (IP address) and provided you with the final answer.

Iterative Query:

Now, let's consider the iterative query scenario where the helper asks for directions and collects information step by step until finding the address.

  1. You: "Hey, can you help me find my friend's house?"

  2. Helper: "Sure! Let's find it together. Do you know if your friend's house is on Main Street?"

  3. You: "I'm not sure, but I think it might be on Main Street."

  4. Helper: "Okay, let's start by going to Main Street and see if we find any familiar landmarks."

  5. You both reach Main Street and see a store.

  6. Helper: "Let's ask someone in the store if they know where John lives."

  7. You and the helper approach the storekeeper.

  8. Helper: "Excuse me, do you know where John lives? We're looking for his house."

  9. Storekeeper: "Oh, John lives a few blocks down this street. Just keep walking straight, and you'll find it."

  10. Helper: "Thank you! Let's continue walking and see if we find John's house."

  11. You and the helper follow the storekeeper's instructions and find John's house eventually.

In this example, the helper (DNS resolver) didn't take on all the work but instead asked for directions (queries) step by step until finding the address (IP address). It's like asking for directions and following the instructions until you reach your destination.

In summary, recursive queries involve the helper doing all the work of gathering information from multiple sources and providing the final answer, while iterative queries involve the helper collecting information gradually, step by step, until reaching the desired result.

  1. DNS Caching

    The helper (DNS resolver) has a good memory. It remembers the IP addresses it found before and keeps them in its cache. So, if you or someone else asks for the same website again, it can quickly give you the answer without searching all over again.

    Imagine you're a kid who loves reading books, and you often go to the library to borrow books. In this example:

    1. You: "Hi, Librarian! Can you help me find a book called 'The Adventures of Alice'?"

    2. Librarian: "Sure, let me check our records and shelves for you."

    3. The librarian searches through the catalog or asks other librarians for the book's location.

    4. Librarian: "Yes, we have 'The Adventures of Alice.' It's in the Fiction section, aisle 3, shelf 2."

    5. You go to the specified location, find the book, and borrow it.

Now, let's say a few days later, you want to borrow the same book again:

  1. You: "Hi, Librarian! Can you help me find 'The Adventures of Alice'?"

  2. Librarian: Instead of searching all over again, the librarian remembers that you borrowed the book recently and has a good memory.

  3. Librarian: "Yes, I remember you borrowed it last time. Let me check our records."

  4. The librarian quickly finds the book's information in their records without having to search for it physically.

  5. Librarian: "Here it is! 'The Adventures of Alice' is still in the Fiction section, aisle 3, shelf 2."

  6. You go directly to the location mentioned by the librarian and borrow the book again.

In this example, the librarian's ability to remember that you borrowed the book recently and quickly provide its location without searching again is similar to DNS caching.

In the context of DNS (Domain Name System), the helper (DNS resolver) acts as a librarian. When you visit a website, your computer asks the DNS resolver to find the IP address associated with the website's domain name. The DNS resolver, just like the librarian, remembers the IP addresses it has found before and keeps them in its cache.

So, if you or someone else asks for the same website again, the DNS resolver can quickly provide the answer without searching all over again. It checks its cache first and retrieves the IP address from there, saving time and effort. This caching mechanism helps improve the speed and efficiency of browsing the internet.

In summary, DNS caching is like the librarian's memory, where the DNS resolver remembers IP addresses it has found before and can quickly retrieve them from its cache when someone asks for the same website again, without needing to search for the information anew.

  1. DNS Servers

    Let's explain DNS servers using an analogy of a city, neighbourhoods, and buildings.

    Imagine you're in a big city, and you want to find a particular building. In this analogy:

    1. You: "Hey, I'm looking for the ABC Building. Can you help me find it?"

    2. Helper (DNS resolver): "Sure! Let's find the information you need."

Now, let's explore the different types of DNS servers that help you find the right building:

  1. Root DNS Servers: These servers are like the city's main information centers. They know which DNS servers to ask for specific neighbourhoods or TLDs (Top-Level Domains). It's like they have a list of phone books or directories for different parts of the city.

    In our analogy:

    • You and the helper approach the main information centre in the city.

    • Helper: "Hello, we're looking for information about the ABC Building. Do you know which neighborhood we should go to?"

  2. TLD DNS Servers: These servers specialize in specific types of websites. They know where to find the information for domains within their TLDs. It's like they have the city's directory for each type of building (e.g., schools, hospitals, businesses).

    In our analogy:

    • The root DNS server provides you with the name of the neighbourhood where the ABC Building is located.

    • Helper: "According to the main information centre, the ABC Building is in the Business District. Let's go there."

    • You and the helper head to the Business District.

  3. Authoritative DNS Servers: These servers hold the actual information for specific websites. They have the IP addresses for the websites in their neighbourhood or domain. When the helper needs an IP address, it asks the authoritative DNS server for that website.

    In our analogy:

    • You and the helper reach the Business District and find a building labelled "ABC Building Authority."

    • Helper: "This is the authoritative DNS server for the ABC Building. They have the information we need."

    • The helper approaches the building and asks for the IP address of the ABC Building.

    • Authoritative DNS Server: "Sure, the IP address for the ABC Building is 123.456.789.0."

With the obtained IP address, you can now reach the ABC Building and access the website it hosts.

In summary, DNS servers are like information centres in a city that help you find specific buildings. The root DNS servers provide general directions, the TLD DNS servers have specialized directories for different types of buildings, and the authoritative DNS servers hold the actual information (IP addresses) for specific websites in their respective neighbourhoods. The DNS resolver acts as your helper, navigating through these servers to find the correct IP address and allowing you to reach the desired website.

DNS Records

Imagine you have a magic notebook, and each page of the notebook has important information about different places. When you want to find a specific place, you look at the page in your notebook that has the right information. DNS records are like those special pages in your notebook that help you find the right IP address for a website.

Here are some common types of DNS records and what they do:

  1. A (Address) Record: An A record is like a note that tells you the IP address of a website. It's like finding the exact location of a place on a map. For example, let's say you have an A record that says "SuperCoolToys.com = 192.168.1.1." This means that when you want to visit the SuperCoolToys.com website, you need to go to the IP address 192.168.1.1.

  2. CNAME (Canonical Name) Record: A CNAME record is like a note that says a website has a different name but leads to the same place. It's like having an alias or nickname. For example, if there's a CNAME record that says "Shop = SuperCoolToys.com," it means that when you visit the Shop website, it takes you to the same place as SuperCoolToys.com.

  3. MX (Mail Exchanger) Record: An MX record is like a note that tells you where to send emails for a specific domain. It's like having a special mailbox for emails. For example, if there's an MX record that says "Mail = mailserver.com," it means that when someone sends an email to a , the email should be sent to the mail server at mailserver.com.

  4. TXT (Text) Record: A TXT record is like a note that contains additional information about a domain. It's like having a little message attached to the address. For example, a TXT record can be used to verify that a website is authentic or to provide instructions for email servers.

Let's summarize with an example: Imagine you have a notebook with a page that says "SuperCoolToys.com = 192.168.1.1." This means that if someone wants to visit SuperCoolToys.com, you tell them to go to the address 192.168.1.1. But if you also have another page that says "Shop = SuperCoolToys.com," it means that when someone wants to visit Shop, they can go to the same address, 192.168.1.1. The notebook also has pages for other special instructions, like where to send emails or additional information about the domain.

So, DNS records are like important notes in a magic notebook that help you find the right IP address for a website, provide aliases or nicknames, direct emails, and contain additional information.

DNS Zone Files

Imagine you have a special folder that contains important papers about a specific place, like a treasure map. This folder is called a DNS zone file. In this case, let's say the folder is called SuperCoolToys.com.

Inside the SuperCoolToys.com folder, there are different papers that tell you important things about that place. Each paper is like a special note that helps you find or understand something specific about SuperCoolToys.com.

Here are some types of notes (DNS records) you might find inside the SuperCoolToys.com folder:

  1. Address Note (A Record)

  2. Alias Note (CNAME Record)

  3. Email Note (MX Record)

  4. Special Note (TXT Record)

So, the DNS zone file for SuperCoolToys.com is like a special folder that holds all these important papers (DNS records). Each paper (record) has specific information about the toy store's address, nickname, email server, or additional details.

Remember, zone files exist for different domains or places on the internet, and they help computers find the right addresses and other important information.

DNSSEC and security considerations

Imagine you have a special lock and key to protect the toy store from any bad guys who might want to pretend to be the toy store or cause trouble. DNSSEC is like that special lock and key that helps keep the toy store safe.

Here's how it works:

  1. Digital Signatures: When you receive a package from the toy store, you want to make sure it's really from them and hasn't been tampered with. DNSSEC uses digital signatures, which are like special stamps of approval, to ensure that the information coming from the toy store is genuine and hasn't been changed.

  2. Authenticity and Integrity: Imagine the toy store sends you a letter with a secret code that only they know. With DNSSEC, the toy store signs their messages using this secret code. When the letter arrives at your house, you can check the signature using the secret code to make sure it's really from the toy store and hasn't been altered.

  3. Protecting Against Bad Guys: Sometimes, bad guys try to trick you by pretending to be the toy store. They might send you a fake letter or give you the wrong address. DNSSEC helps protect against these bad guys by making sure you only trust information that has been properly signed and verified by the toy store.

In our example, let's say the toy store has implemented DNSSEC. When you visit their website, your computer checks if the information it receives from the DNS server is properly signed with a digital signature. It ensures that the website you're accessing is the real SuperCoolToys.com and not a fake one created by bad guys.

Additionally, security considerations involve taking extra precautions to keep the toy store and its information safe. This includes:

  • Access Controls: It's like having security guards at the entrance of the toy store who only allow authorized people to enter. Similarly, access controls in DNS ensure that only trusted and authorized individuals or computers can make changes or access sensitive information.

  • Regular Updates: Just like the toy store needs to regularly check its security systems and make improvements, updating DNS servers and implementing security patches help keep everything secure and up to date.

By using DNSSEC, access controls, and regular updates, the toy store can protect itself from bad guys and make sure that only trustworthy information is shared with its visitors.

So, DNSSEC is like a special lock and key system that ensures the toy store's messages and information are genuine, protecting against fake or altered information. Security considerations involve additional measures like access controls and regular updates to keep everything safe.

Conclusion

Our exploration of DNS has shed light on its importance as a vital infrastructure of the internet. By understanding the components, resolution process, and security considerations, we have gained a comprehensive overview of DNS and its significance in our daily online interactions. In our next adventure, we will delve into the details of HTTP (Hypertext Transfer Protocol) - the foundation of data communication on the World Wide Web. Stay tuned as we unravel the inner workings of HTTP and discover how it enables seamless browsing and interaction with websites.

Stay curious, and let's explore the web together!

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