What Is DNS Server and How It Works?
Have you ever wondered how your computer is able to find a website when you type its domain name in the browser’s address bar? The magic behind this process is performed by a technology called DNS (Domain Name System) and its associated servers. In this article, we will dive into the world of DNS servers and understand how they work.
DNS is like a phone book for the internet. It translates human-readable domain names (such as www.example.com) into machine-readable IP addresses (such as 192.168.0.1). This translation is necessary because computers communicate with each other using IP addresses, but remembering numbers for every website would be impractical.
The Role of DNS Servers:
DNS servers play a vital role in the translation process. When you enter a domain name in your browser, your computer sends a request to a DNS server to resolve the corresponding IP address. There are different types of DNS servers involved in this process, including recursive resolvers, authoritative servers, and root servers.
A recursive resolver is usually provided by your Internet Service Provider (ISP) or a third-party service like Google Public DNS or Cloudflare DNS. Its primary function is to receive your request for translating a domain name into an IP address and perform all necessary steps to find the answer.
Authoritative servers are responsible for storing specific domain information. When a recursive resolver receives your request, it starts by querying an authoritative server that holds the relevant information for the requested domain.
Root servers are the backbone of the DNS system. They store information about the top-level domains (TLDs) like .com, .net, .org, and country-specific TLDs. They help in resolving queries by directing them to the appropriate authoritative servers.
The DNS Resolution Process:
Now that we have an overview of the different types of DNS servers, let’s understand how they work together to resolve a domain name.
- Your computer sends a request to a recursive resolver to resolve a domain name.
- The recursive resolver checks its local cache for the requested domain’s IP address. If found, it returns the IP address directly to your computer.
- If not found in the cache, the recursive resolver queries the root servers to find the appropriate TLD server.
- The recursive resolver then queries the TLD server for further direction on which authoritative server holds the requested domain’s information.
- The recursive resolver finally queries the authoritative server and receives the IP address for your requested domain.
- The recursive resolver stores this information in its cache for future use and returns the IP address to your computer.
Caching and TTL:
To improve performance and reduce load on DNS servers, caching is used at multiple levels. Recursive resolvers cache responses they receive from various servers, reducing subsequent query times for frequently visited websites. Each response also includes a Time-to-Live (TTL) value, which specifies how long this information can be considered valid before it needs re-validation from authoritative servers.
DNS servers are crucial components of our internet infrastructure. They facilitate seamless translation between user-friendly domain names and machine-friendly IP addresses. Understanding how they work helps us appreciate the complexity involved in resolving domain names and accessing websites on the internet.
So, the next time you enter a domain name in your browser, remember that behind the scenes, DNS servers are working diligently to make sure you reach your destination.