What is the Domain Name System?
The Domain Name System, or shortly DNS, is an infrastructure that brings simplicity for humans to using the Internet as we know it in present days. It has extensive functionality. However, at its core, it holds a database with all of the domain names that exist and their associated IP addresses.
When a user types a domain name that it wishes to visit is triggering a whole DNS process that is not so straightforward. The particular domain name has to make a transformation into a language that computers and machines understand and can use to communicate. We need the IP addresses (IPv4 and IPv6) for that purpose. Without such translation, the machines won’t be able to communicate and interact with each other.
After finding the IP address corresponding with the domain name, the process finishes when the browser of the user receives it, and it is able to connect with the website.
When we look back to when DNS did not exist yet, it was necessary to enter the IP address, like 188.8.131.52, to visit a specific web page. Instead, now we just have to remember easy names, like domain.net, which is much more convenient. Thanks to DNS, we access websites without any memory difficulties.
Domain Name System (DNS) lookup – What is it?
The DNS lookup refers to a long searching process that repeats millions of times every day. Let’s break it down!
- It starts with a user typing a domain name on its browser, which queries a recursive DNS nameserver. It asks for DNS data, like DNS records and IP addresses (IPv4 and IPv6).
- The recursive DNS server is going to seek that data in its cache memory. If it is available there, it is going to reply with it, and the search will be completed.
- However, if it’s not in the recursive DNS server cache memory, it is going to seek for it to the root server. The root server is able to give information which is the related TLD name server for the particular requested domain name.
- Next, the recursive DNS server is going to ask the TLD server to reveal which is the authoritative DNS server for the specific domain name. Then, the recursive is going to get from this final server the IP address.
- The recursive DNS server finally gets back with the IP address to the browser. Lastly, the browser connects to the domain name, and the user can explore the website.
The different DNS servers
- Root server. In the Domain Name System hierarchy, the root servers are on top, and they provide information about the TLD servers. They hold the root zone file, where is the entire information about all available TLDs.
- The TLD server. Top-Level Domain servers are authoritative name servers. Each of them is responsible for the different TLDs, such as .com, .net, .info, etc.
- Authoritative DNS server. The authoritative DNS name server holds the original zone file for the particular DNS zone it is accountable for. These servers are going to deliver an authoritative answer when they are queried.
- Recursive DNS servers. These servers do not hold original zone files. Recursive servers only cache duplicates for a brief period of time. Their main aim is to search for answers and respond to DNS queries.
Suggested article: DNS propagation: What is it, and how to check it?