The Domain Name System is a popular approach used in the translation of domain names to their IP addresses. This system maps each domain name with the IP address stored against them. This way, users never need to recall the IP address of each website. In this article, we will be going through the DNS server along with other relevant concepts of it.

🌐 What is DNS?

The Domain Name System (DNS) is a client-server model that aims at mapping domain names to IP addresses. Users don't need to remember the IP address of each website but can refer to the IP address using the domain name. For instance, when you type "www.example.com" in the address bar and hit enter, the first task is to map the domain name to the IP address. This procedure is called "translation."

Domain names are alphabetical, making them easier to remember than the stream of numbers in an IP address. When you use a domain name, the DNS service converts the name to the corresponding IP address, making the web address more convenient. Reverse lookup is a strategy where we query the domain names associated with the specified IP address.

🔢 What is the IP address?

An IP address is a unique combination of digits for a device connected to the internet. An IP address can also exist within the same Local Area Network (LAN). IP stands for "Internet Protocol," which is a set of protocols that handles the format of data and what principles the users and network engineers must follow when the data is transmitted over the internet or a local network.

An IP address is a sequence of digits separated by dots. Each IP address block is represented by a four-digit permutation, such as 192.158.1.38. Each integer in the set can have a value between 0 and 255. As a result, the IP addressing range extends from 0.0.0.0 to 255.255.255.255.

The Internet Assigned Numbers Authority (IANA), a division of the Internet Corporation for Assigned Names and Numbers (ICANN), assigns IP addresses to each device. It is a non-profit organization founded in the United States in 1998 to help preserve the security and accessibility of the internet.

IP addresses are also helpful in transferring files over the network, especially while working with virtual machines. The IPv4 address scheme has four sections where each value ranges from 0 to 255. While IPv4 is common, many modern systems are transitioning to IPv6 VPS solutions to accommodate more devices.

The IP address can be either dynamic or static. A static IP address scheme does not change the address, while a dynamic address scheme keeps changing the address. A static address scheme is usually used for computer engines and live gaming, where a static IP address is required.

🖥️ What is a DNS server?

A DNS server is a giant database of domain names that are mapped to IP addresses. Consider them as a phone book where you don't need to remember the contact number of each person but can get it using the contact name saved against it. If you are managing your own infrastructure, you might even look into Windows Server DNS setup to handle internal queries.

There can be multiple DNS servers for each ISP. DNS servers communicate with one another by exchanging domain names, IP addresses, or pointers to other DNS servers that are authoritative for that domain.

The most famous example of a DNS server is the Google DNS server. This is also considered a public DNS server and it is free to use.

📂 Types of DNS servers

Server Type Primary Role Analogy
Recursive Resolver Receives client requests and finds the IP. The Librarian
Root Nameserver Directs the resolver to the correct TLD. The Information Desk
TLD Nameserver Handles specific extensions (.com, .net). The Category Shelf
Authoritative Nameserver Holds the actual IP address record. The Specific Book

🔍 DNS recursive resolver

This is the first gateway that interacts with the client request. This server acts as a middleman between the client and DNS nameserver. It either returns cached data or will forward the request to the root name server.

🌳 DNS root nameserver

A root server accepts a recursive resolver's request containing a domain name. This server responds by directing the recursive resolver to a TLD nameserver based on the domain's extension. The extension can be .com, .net, .org, and so on. The Internet Corporation for Assigned Names and Numbers (ICANN) manages the root nameservers.

🏷️ TLD nameserver

This server contains information related to common extension domain names. For instance, the ".net" server includes information on all the domain names having this extension.

👑 Authoritative DNS server

The authoritative nameserver has information specific to the domain name it serves (example.com) and provides the IP address of the requested domain name to the recursive resolver. A DNS server is the authoritative (point of origin) server for the DNS zone whose data you're looking for.

⚙️ How DNS servers work

The client-server network architecture underpins DNS. When you navigate through websites, your web browser acts as a client (DNS Resolver), requesting DNS servers from your ISP (internet service provider) to determine whether the domain name is resolved on a server.

When a DNS server receives a request, it temporarily assumes the role of a DNS client. If the address cannot be resolved, the server forwards the request to another DNS server, and the process is repeated until the request reaches a server with a matching IP address. The response is then routed through the DNS server chain back to your browser.

The DNS resolver is the client-side of the DNS resolution mechanism. These resolvers are typically divided into three types:

  • Recursive: The resolver does all the work to find the IP.
  • Non-recursive: The resolver knows exactly where the record is or it's in cache.
  • Iterative: The resolver refers the client to another server if it doesn't have the answer.

DNS is a protocol in and of itself and does not make use of HTTP GET or POST requests. The DNS protocol can communicate via UDP or TCP. UDP is preferred for regular queries because most requests are small, reducing latency.

🗺️ DNS server zones and records

A DNS Zone is an administrative control unit. It has a domain and possibly multiple subdomains, as well as at least three DNS records - the SOA (Start of Authority) record and two NS (Name Server) records. In practice, a zone is a collection of DNS records that are managed as a unit.

A DNS record is a single item that describes a specific feature of a zone. Essential records include:

  • A record: Connects a name (www.example.com) to an IPv4 address.
  • AAAA record: Similar to the A record but uses an IPv6 address.
  • CNAME: Forwards one domain to another domain (Alias).

⚡ How to optimize the DNS query

We can store the results locally in order to reduce the effort put on the DNS servers. The results that we get from the servers have the Time-to-Live (TTL) associated with it. This determines after what time we need to discard or refresh the results. If you encounter issues, you might need to learn how to flush DNS entries to clear old data.

There are many optimized DNS servers out there. To choose the best DNS server, you can use specialized tools or check an updated list of free addresses. Using a faster DNS can significantly improve your browsing speed and security.

🎯 Conclusion

In this article, we went through the details of DNS servers and saw how they solve a significant problem in the networking world. We explored the sequence of servers that contribute to the translation of domain names to IP addresses, ensuring the web remains accessible and user-friendly.

Since it is not possible for a human to memorize the unique IP addresses of every machine in the global network, we rely on the Domain Name System to bridge the gap. By understanding how these servers function, from caching to record types, you can better optimize your own network performance.

People also read: