Recursive DNS server is really important. Without it, looking for something on the Internet could be really frustrating. Right now, you can reach this article thanks to a Recursive DNS server’s service! They work a lot to our benefit, but we don’t realize it because they are kind of low-profile components.
Let’s get familiar with the Recursive DNS server to give it proper credit!
What’s a Recursive DNS server?
A Recursive DNS server or DNS resolver is a professional searcher. Yes, it’s the one that searches for the necessary data to answer users’ DNS requests.
It’s a vital and efficient component of the DNS machinery. Recursive comes from recursion, a word that in the context of computing points out a solution or a specific process that will replicate as many times as needed for accomplishing an objective. And that description matches very well with the way a Recursive DNS server operates.
Every time a user wants to visit a domain, when he or she requests it through the browser, a DNS resolver comes to the scene to look for the domain’s corresponding IP address. Getting it can be fast and easy or take more steps and time. But the server won’t stop searching until it gets it. Then it will send it to the browser for the user (device) to finally load and visit the requested domain.
How does a Recursive DNS server work?
A Recursive DNS server works in two ways.
This type of server can cache DNS data in its memory during a specific period, not permanently. That time is defined by the TTL (time-to-live) established on the DNS records (DNS data). Once the TTL expires, data won’t be available in the server’s memory anymore. So when you visit a domain for the first time, a complete search must be made to get the DNS data. But once you have visited it at least once, data from the previous search can be cached.
Let’s repeat the scenario of a user typing a domain name in the browser. This will trigger the search of the domain’s IP address by a Recursive DNS server. The first choice for the server is to check directly within its cache memory. If the TTL of the requested IP address hasn’t expired yet, it must be there. If it’s found, the server will answer the user’s request really fast.
But it can happen that the IP address is not in the server’s cache. Then, it will execute a deeper search that involves walking through the DNS tree (DNS Hierarchy). It will visit the root server first to know which TLD server can help to find the requested data. Then it will go to that TLD server to know which is the Authoritative nameserver for the second-level domain name that stores such data. And finally, it will get the IP address from this last server. The IP address will be sent to the user’s browser to load thedomain. This search definitely takes extra steps for the Recursive DNS server, but still, everything happens in milliseconds!
Recursive DNS servers work in the DNS backstage, and they are critical for domains and online services to be accessed. On one side, you have Authoritative DNS servers that host DNS data of domains and the IP addresses linked to every domain. On the other, you have users, your potential clients! A Recursive DNS server plays in between them, connecting them!