How does a Recursive DNS server operate?

Recursive DNS server: What does it mean?

In computers, recursion refers to a technique for addressing a problem. That calls for an answer or a strategy that will keep repeating itself until it achieves its objective. So, the Recursive DNS server is in charge of looking up the information required to respond to DNS requests made by users.

Recursive DNS servers serve as a bridge between end users and authoritative DNS servers. A recursive DNS server will look up the IP address whenever a domain name is entered. This server returns to the browser on the requested device after determining the precise IP address for the requested domain name. By connecting to that IP address, the device is finally able to access the required website, and the website is loaded.

Weaknesses of Recursive DNS servers

Recursive DNS server and DNS cache poisoning

The attacker halts the request when a recursive DNS server looks up an IP address from another DNS server. The attacker will provide an incorrect response in place of the actual information. Typically, this response is an IP address for a rogue website. The DNS cache poisoning attack has thus been effective.

The recursive server provided the user’s bogus IP address, but it is not the only issue. Additionally, the server will keep the solution in its cache. This fact creates a significant problem. Users attempting to access the same domain will be assigned a phony IP address to connect them to the malicious website. Consider a scenario where that domain is prevalent. There will be many visitors who this incident will impact.

How does it operate?

There are two ways a Recursive DNS server operates.

This server can temporarily store DNS data in its memory, not indefinitely. The TTL (time-to-live) set on the DNS records determines that duration (DNS data). Data will no longer be accessible in the server’s memory after the TTL has passed. Therefore, a thorough search must be performed to obtain the DNS information when visiting a domain for the first time. The information from your prior search can be cached once you’ve been there at least once.

Replay the situation where the user types a domain name into the browser. This will cause a Recursive DNS server to look up the domain’s IP address. The server’s first option is to perform a direct check in its cache memory. The specified IP address’s TTL must be present if it hasn’t already expired. The server will respond to the user’s request very quickly if it is.

However, it is possible that the server does not currently cache the IP address. Then, it will conduct a more in-depth search by traversing the DNS tree (DNS Hierarchy). It will first contact the root server to determine which TLD server can assist in locating the requested material. Then it will visit that TLD server to find out which nameserver is the official one for the second-level domain name that houses such information. The IP address will then be obtained from this final server. The user’s browser will provide the IP address to load the domain. Even though the Recursive DNS server must go through extra steps to perform this search, everything happens in milliseconds!


Finally, you may proudly state that you know the Recursive DNS server’s function. Its ability to cache data information is its key advantage. As a result, it offers a prompt response to the query.