What is DNS? Full Form, Servers, and How It Works

What is a DNS server? Put simply, a DNS server is the internet’s telephone directory, allowing you to translate website names (example.com) to the numbers (IP addresses) computers use to find one another. Without DNS servers, web browsing would be much more difficult; you’d have to remember long IP addresses in memory each time you wanted to visit a website. In this guide, we’ll cover what DNS is, how DNS servers work, and why they are critical to our everyday use of the internet.

What is DNS?

DNS (Domain Name System) is a phonebook for the Internet. It helps translate website names like “example.com” to IP addresses, numbers (like 203.0.113.72) that computers use to find each other on the internet.

When you type a website name in to your browser, you can’t see it, but DNS is the system that connects you to the IP address for that website. This process happens behind your browser, but is essential for surfing the web.

Different organizations, like internet providers, universities, and businesses, have their own IP addresses and domain names. They also manage DNS servers to link these names to the correct addresses. So, whenever you visit a website, DNS helps you find it quickly.

How DNS Works?

DNS (Domain Name System) is like an address book for the Internet. It helps convert the easy-to-remember website names (like “example.com”) into IP addresses (like 203.0.113.72) that computers can understand.

Here’s how DNS works step by step:

1. User Enters a Web Address:
   When you type a website address (like “example.com”) into your browser, the browser needs to figure out which IP address corresponds to that website.
   
2. Recursive DNS Query:
   The browser sends a request called a recursive DNS query to the Internet. This request asks for the IP address linked to the domain name you entered.
   
3. Recursive DNS Server (or Resolver):
   The recursive DNS server (also called a recursive resolver) receives this query. This server is usually managed by your internet service provider (ISP). If this server already knows the IP address, it directly sends it back to your browser, and the webpage loads.
   
4. Querying Other Servers:
   If the recursive DNS server doesn’t know the answer, it will ask other servers to find the correct IP address. These servers are:
   
   • DNS Root Name Servers: The first place the query is sent. These servers know the address of other servers but don’t have the full answer.
     
   • Top-Level Domain (TLD) Name Servers: After root servers, the query is sent to TLD servers (for example, “.com” or “.org”).
     
   • Authoritative Name Servers: These are the final servers that hold the actual IP address for the domain name. They provide the answer and send it back to the recursive DNS server.
     
5. IP Address Found:
   The authoritative name server sends back the IP address (DNS record) to the recursive DNS server, which in turn sends it to your browser. The webpage then loads.
   
6. Caching the IP Address:
   To speed things up, the recursive DNS server stores (or “caches”) the IP address of the domain name for a period of time. So, if the same address is requested again, it can respond directly without asking other servers.
   
7. Error Handling:
   If the query reaches the authoritative server and it can’t find the information, it returns an error message.

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Key Terms

• DNS: Stands for Domain Name System, which is responsible for translating domain names into IP addresses.
• DNS Server: A server that handles DNS queries. It helps translate domain names into IP addresses.
• Recursive Resolver: The DNS server that handles requests and finds the IP address by querying other servers.
• Authoritative Name Server: The server that has the final answer for the IP address of a domain name.
• A Record: A DNS record that links a domain name to an IP address.

Why is DNS important?

Without DNS servers and the Domain Name System, we’d have to remember long strings of numbers (IP addresses) to go to websites, rather than easy-to-remember domain names. DNS resolution is what allows us to quickly and easily browse the World Wide Web, translating human-friendly names to machine-friendly IP addresses.

Authoritative DNS Servers vs Recursive DNS Servers: What’s The Difference?

When you’re browsing the web and you type in a URL, there are two main types of DNS servers involved: Authoritative DNS servers and Recursive DNS servers. Let’s break down what each one does and how they work together.

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Authoritative DNS Server

Think of an Authoritative DNS server as the “final authority” in the world of domain names. If DNS was like a phone book, the authoritative server is the one that holds the actual phone numbers (IP addresses) for each name (domain). So, when you want to find out where a website is, the authoritative server is the one that has the correct information.

To use a simple analogy:

• The domain name is like a person’s name.
• The IP address is like their phone number.

The Authoritative DNS server holds the list of domain names and their matching IP addresses. When a recursive DNS server can’t find the answer in its own cache (we’ll get to that in a second), it goes to the authoritative server for the correct info.

These servers are responsible for certain parts of the internet, like a specific country, organization, or even a local area. They do two things:

1. They keep the list of domain names and their associated IP addresses.
2. They respond to recursive DNS servers with the right IP address for a requested domain.

Once the recursive server gets the IP address from the authoritative server, it sends it back to your browser, and the website loads.

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Recursive DNS Server

Now, think of a Recursive DNS server as the middleman. It’s the one that helps you get from a domain name to the actual website. When you type a URL into your browser, it’s this server that first takes a look at whether it already knows the IP address for that domain.

Here’s how it works:

1. The recursive DNS server checks its memory (called cache) to see if it already knows the IP address for the domain.
2. If it does, it sends the IP address right back to your browser, and the website loads quickly.
3. But if the recursive DNS server doesn’t know the IP address, it’s like a detective—it has to go through a series of steps to find the answer.

It will start by querying root DNS servers, then top-level domain (TLD) servers, and finally it reaches the authoritative DNS server to get the correct IP address. Once it gets the answer, it sends the IP address back to your browser and stores it in its cache for a certain amount of time, so next time you visit, it can respond faster.

The amount of time it keeps the IP address is called Time To Live (TTL). This TTL is set by the owner of the domain, and it tells the recursive server how long to remember the IP address.

Both types of servers work together to help you reach the website you want to visit. The recursive server does the legwork to find the IP address, and the authoritative server holds the correct and final information.

Conclusion

DNS (Domain Name System) is like the internet’s phonebook that takes the human website name and converts that into numbers that computers can understand. As humans, we would have a difficult time finding websites if we had to remember long numbers in order to get to them. DNS operates through recursive servers, which search for the correct IP and save it for later use, and authoritative servers, which ultimately have the answer. In this way, DNS allows us to get to our websites in a quick and easy process by simply typing in their name.