What is DNS and how does it work?

Introduction

DNS, or Domain Name System, is a fundamental component of the internet's infrastructure, acting as the internet's directory. It translates human-readable domain names like www.example.com into IP addresses that computers use to identify each other on the network. This system is crucial for the functioning of the internet as it allows users to access websites using easy-to-remember names instead of a string of numbers.

How Does DNS Work?

The DNS process involves several steps:

1. DNS Query Initiation: When a user enters a URL in their web browser, a DNS query is initiated.
2. Recursive DNS Resolver: This query is sent to a recursive DNS resolver, usually provided by the user's internet service provider (ISP). The resolver acts as an intermediary between the user and the DNS server.
3. Root DNS Servers: The resolver first contacts one of the root DNS servers. These servers do not know the IP address of the desired domain but can direct the resolver to the appropriate Top-Level Domain (TLD) server (e.g., .com, .org).
4. TLD DNS Servers: The resolver then queries the TLD server, which directs it to the authoritative DNS server for the specific domain.
5. Authoritative DNS Server: The resolver queries the authoritative DNS server, which contains the actual DNS records for the domain. It responds with the IP address of the requested domain.
6. Response to User: The resolver returns the IP address to the user's web browser, which can then request the web page from the web server at that IP address.

Components of DNS

The main components of DNS include:

• Domain Names: Hierarchical names used to identify entities on the internet. They are divided into labels separated by dots, such as www.example.com.
• DNS Records: Data entries that map domain names to IP addresses and other resources. Common types of DNS records include:
  • A Record: Maps a domain to an IPv4 address.
  • AAAA Record: Maps a domain to an IPv6 address.
  • CNAME Record: Maps a domain to another domain (canonical name).
  • MX Record: Directs email to mail servers.
  • TXT Record: Stores text information, often for verification and security purposes.
• DNS Zones: Segments of the DNS namespace that are managed by a specific organization or administrator. Each zone has its own set of DNS records.
• Root Servers: The highest level in the DNS hierarchy. They direct DNS queries to the appropriate TLD DNS servers.