DNS Network

Understanding Recursive DNS server

Today, we will take a deep look at the Recursive DNS server. What is its primary purpose, its specification, and the types of lookups, we will explore now. So, let’s start.

Recursive DNS server – A detailed explanation 

The Recursive DNS server is in charge of looking up information. The purpose is to react to queries submitted by users. In technology terms, recursion refers to a method for resolving a problem. It entails a solution or program that will keep repeating until it achieves its purpose.

Consider it in this light. It functions as a link between authoritative servers and end-users.

This DNS server looks up a domain name’s IP address whenever it receives a request for it. It returns the proper IP address to the device or browser that originated the request once it gets it. Then, the machine receives the information and connects to the assigned IP address. Finally, the domain can be accessed.

Different kinds of lookups

The lookup could be completed in two ways by the Recursive DNS server:

  1. The first form is thought to be much simpler and speedier. This is because the IP address is stored in its cache memory. These servers can retain information in their cache for a period of time. The administrators will decide how long they should keep it. They can use the time-to-live (TTL) value to calculate more or less time. Actually, everything depends on the administrators’ strategy. When the Recursive DNS server receives the query, it will first look for the IP address in its cache memory. The assignment is complete if that information is still available there and the TTL has not yet expired. It’s helpful since the response is quick, and the Recursive DNS server doesn’t have to look for information on other servers.
  1. The second type of search will take a little longer to finish. It occurs when the cache’s TTL has passed its expiration date. As a result, the IP address is no longer accessible. On the other hand, the Recursive DNS server goes a long way toward obtaining the needed information. It travels from the root server to the TLD (Top-Level-Domain) server to the authoritative server, which is the one that can answer the question.
    As a result, the Recursive DNS server’s primary aim is to search for information.

Recursive DNS server dangers

Because cybercriminals understand how vital a Recursive DNS server is, they take advantage of it.

Some Recursive servers are visible to the public network, making them easy targets for criminals. 

Black hat hackers can use them to launch DoS (or DDoS) attacks and DNS poisoning. In addition, they can target servers directly to bring them down, also known as DNS outage.


Recursive DNS servers are critical components for the DNS resolution process to run quickly and for the Internet to be a pleasant experience most of the time. Without them, it may be challenging to meet the high volume of requests that are generated on a daily basis. The fact that there are so many of these servers in the world is not by chance!

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