The DNS infrastructure is really helping the experience of Internet surfing pleasant and easy. One of the main responsible participants is the recursive DNS server. So let’s explain a little more about it and its role in the complex DNS process.
DNS – What is it for?
The Domain Name System, or DNS for short, is a well-established method of translating domain names into IP addresses. When a user wants to visit a website, it will usually search in its browser for it. To accomplish this task, the user is going to write the domain name of the website. Unfortunately, the machines don’t understand words and names, and they work only with numbers to communicate. So in the middle is the Domain Name System, and it is solving this issue by pointing the particular domain name to its corresponding IP address.
Recursive DNS server explained.
Recursion in computing is often associated with a method of solving a particular issue. Thus, it involves a program or solution that will keep repeating itself till it reaches its goal.
Recursive DNS servers operate between the user and the authoritative DNS servers. They perform the required searches for specific information to find an answer to the queries of the users.
As we mentioned, the users make a request for a particular domain through a browser. Yet, the process of searching for the correct IP address is performed by a recursive DNS server. Therefore, it is important to note that they are not the holders of the database with information. They are the searchers. After the recursive DNS server finds the required IP address, it gets back to the device and provides it to the browser that requested it. Finally, the device is able to connect to the IP address, and the user reaches the website.
Globally the number of recursive DNS is significant. The most popular of them are the ones of your Internet service provider (ISP).
The two types of lookup
The recursive DNS server performs its lookup in one of two ways. They are the following:
The first type one is considered a lot easier and quicker. This is because it contains the IP address from its cache memory. For a particular time, these servers can store the information in their cache. For what amount of time they should hold it is a decision made by the administrators. They can determine more or less time by the time-to-live (TTL) value. It is all based on the strategy of the administrators actually.
Receiving the query, the recursive DNS server is going to first search for the IP address in its cache memory. If that information is still available there and the TTL has not expired yet, the assignment is completed. It is very beneficial because the response is fast, and the recursive DNS server doesn’t need to search further in other servers.
The second type of search requires a little bit more time to be completed. It occurs in the cases when the TTL in the cache is expired. For that reason, the IP address is no longer available there. However, the recursive DNS server goes a long way to obtain the desired information. It passes through the root server, TLD (Top-Level-Domain) server, and finally to the authoritative server, which is the one able to provide the answer to the query.
Therefore, the original goal of the recursive DNS server is only to search for information.