Internet Series: DNS and How It Works? – Medium

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The internet is a giant network that connects millions of devices around the world. Every time you visit a website, you type in its name, like www.google.com or www.facebook.com. But how does your computer know where to find the website? This is where DNS, or the Domain Name System, comes in. DNS is like the internet’s phonebook. It helps computers turn website names into something they understand: IP addresses. Without DNS, using the internet would be much harder.
Let’s talk about what DNS is, how it works, and why it’s so important.
The Domain Name System (DNS) is like a phonebook for the internet. Imagine you want to visit your friend’s house. You know their name, but you don’t know their address. Similarly, when you type a website’s name, like www.example.com, your computer doesn’t know where that website is. DNS helps by finding the address of the website, also known as its IP address.
For example:
When you type www.google.com, DNS finds the IP address so your computer can connect to the website.
Before DNS, people had to remember IP addresses to visit websites. Imagine trying to memorize numbers like 192.168.1.1 or 216.58.214.14 for every website. DNS makes life easier by letting us use simple names instead of numbers. It also keeps things flexible. If a website changes its IP address, DNS updates it without you having to do anything.
DNS is organized like a tree with different levels. Each level has a specific job to do. Let’s break it down step by step.
The DNS system has four main parts:
Root servers are at the very top of the DNS system. There are 13 root servers in the world, but each one has many copies in different places. These servers don’t have the IP addresses of websites. Instead, they point to the next layer: the TLD servers.
Example: If you type www.example.com, the root server sends your query to the .com TLD server.
TLD servers handle domain extensions like .com, .org, .net, or country-specific ones like .pk (Pakistan) or .uk (United Kingdom). These servers direct your query to the authoritative name servers for the specific domain.
Example: For www.example.com, the .com TLD server points you to the authoritative name server for example.com.
Authoritative name servers store the actual DNS records for a domain. These records tell your computer the IP address of the website you want to visit.
Example: The authoritative name server for example.com might return the IP address 192.0.2.1.
Recursive resolvers are not part of the hierarchy, but they play a big role. They act like helpers between your computer and the DNS system. When you type a domain name, the resolver does all the work of asking the root, TLD, and authoritative servers to find the IP address.
Example: If you type www.example.com, the resolver:
Let’s go through an example to see how DNS works in real life. Suppose you want to visit www.example.com:
Imagine you want to call a friend named Sarah. You know her name but not her phone number. You look up her name in a phonebook, find her number, and call her. DNS works the same way:
Think of a domain name as a store’s name, like “Best Coffee Shop.” The IP address is the store’s street address, such as “123 Coffee Lane.” DNS acts like Google Maps, helping you find the store’s location based on its name.
To make things faster, DNS uses caching. Once your computer finds the IP address of a website, it remembers it for a while. The next time you visit the same website, your computer doesn’t need to go through the whole DNS process again. It just uses the stored information.
Example: If you visit www.google.com, your computer saves its IP address. The next time, the website loads faster because the IP address is already known.
DNS is distributed, which means it’s not all handled by one server. This prevents overload and ensures that even if one server goes down, others can handle the requests.
DNS records are like instructions that tell DNS servers how to handle specific domain names. Each type of record serves a particular purpose. Let’s break down the most common types of DNS records:
Each of these records plays a crucial role in making websites, email, and other internet services function smoothly.
DNS resolution is the process of converting a domain name into an IP address so your browser can connect to a website. Here’s how it works step by step:
This entire process happens in just a few seconds, allowing you to browse the internet seamlessly.
DNS caching is a way to speed up DNS resolution by storing the results of previous queries temporarily. It reduces the time and effort needed to resolve a domain name again. Here’s how it works:
Example of DNS Caching in Action:
Caching ensures faster browsing and reduces the load on DNS servers, but it also means changes to DNS records (like a new IP address) might take some time to update everywhere.
DNS propagation refers to the time it takes for DNS changes to spread across the internet. When you update DNS settings, like changing a domain’s IP address, these changes don’t take effect instantly everywhere. Here’s why:
How Long Does DNS Propagation Take?
Example of DNS Propagation:
Tips to Minimize Propagation Delays:
While DNS is crucial for the internet, it’s also a target for cyberattacks. To keep DNS secure, various measures are in place. Let’s explore the most common threats and protections:
What Is DNSSEC?
Why Is DNS Security Important?
DNS is the backbone of the internet, acting as a bridge between human-friendly domain names and machine-readable IP addresses. It ensures that we can access websites, send emails, and use online services seamlessly. From DNS records that guide how domain names are handled, to caching that speeds up access, and security measures like DNSSEC that protect users from attacks, every component plays a vital role.
Understanding how DNS works gives us an appreciation for its complexity and importance in our daily digital lives. Whether you’re a regular internet user or someone managing websites, knowing about DNS can help you navigate the internet more effectively and securely.
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I’m Qurat Ul Ain (Ainy), and I create simple projects to learn and grow. I share what I learn through blogs, videos, and designs.
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