Explaining each step of DNS resolution

DNS resolution – What is it?

The DNS resolution is an entire behind-the-scene process that includes obtaining the IP address of a particular domain name. The Domain Name System (DNS) is built-in hierarchal order, and it includes several levels responsible for different information about the domain. 

Every server storing original DNS information for a DNS zone is also known as an authoritative DNS server. This is because it can provide the newest and correct information about the domain name. Recursive DNS servers, also known as DNS resolvers, are the other important participants in the DNS resolution process. Their purpose is to search and obtain the DNS data and to store it for a time period defined by the TTL values.

The process of DNS resolution

The DNS resolution process is triggered every time you want to connect with a website you haven’t visited before. So, let’s break down the process into several steps.

1. It all starts when you type the domain name in your browser. A DNS query is made, and the DNS lookup process begins for finding the IP address of the domain name.
2. The recursive DNS server receives the DNS query. First, it is going to check if the needed data is available in its DNS cache. In case it is not found there, this server is going to ask the rest of the DNS servers and gather all of the needed data. 
3. The Root server is the first stop of the search of the recursive DNS server. On the DNS hierarchy, the Root is on the highest level. It provides information about the location of the TLD (Top-Level Domain) server for the precise domain name. For example, .info, .com, .net and so on.
4. The TLD server, which is one level below the Root server, provides details about the accurate nameserver for the domain name.
5. Then the Recursive DNS server asks the authoritative nameserver for the exact domain name. Finally, this last server is able to give the proper information and IP address.
6. Once the Recursive DNS server has the answer to the DNS query, it brings it back to the user. Additionally, it is going to save it in its DNS cache for further use.
7. The browser presents the requested website, and you can explore it.

Why is it important?

The process of DNS resolution is fundamental for humans. It would be a severe challenge for standard users to use the Internet. If we look back at the time when the Domain Name System (DNS) was not developed, it was necessary to remember the IP addresses for the websites you wanted to visit. It sounds like a hard assignment!

Thankfully, the DNS now allows us only to remember the simple domain names, and we can easily explore the requested content.