What is a DNS?

DNS (Domain Name System) is a fundamental component of the internet. DNS is a hierarchical and distributed system used to translate human-friendly domain names (like www.example.com) into IP (Internet Protocol) addresses that computers use to identify one another on the network. In essence, DNS serves as the "phone book" of the internet, allowing you to access websites and online services using easily recognizable domain names instead of numerical IP addresses.

Here's how DNS works:

• User Input: When you type a website's URL (Uniform Resource Locator) into your web browser (e.g., www.example.com), your device needs to find the corresponding IP address to establish a connection with the web server hosting that website.
• DNS Query: Your device sends a DNS query to a DNS resolver (usually provided by your internet service provider or a third-party DNS service). The query contains the domain name you want to visit.
• DNS Resolution: The DNS resolver checks its local cache to see if it already knows the IP address for the requested domain. If the information is not in the cache or has expired, the resolver needs to fetch the IP address.
• Recursive DNS Server: If the resolver doesn't have the information, it contacts a recursive DNS server. This server is responsible for finding the IP address of the requested domain.
• Root DNS Server: The recursive DNS server begins a series of queries starting at the root level of the DNS hierarchy. The root servers have information about the top-level domains (TLDs), such as .com, .org, .net, and country code TLDs like .uk or .jp.
• TLD DNS Server: The root DNS server directs the recursive server to the TLD DNS server, which manages the specific top-level domain of the requested domain name (e.g., .com or .org).
• Authoritative DNS Server: The TLD server points the recursive server to the authoritative DNS server responsible for the requested domain. This authoritative server stores the definitive IP address for the domain.
• IP Address Retrieval: The recursive server retrieves the IP address from the authoritative DNS server and caches it for future use.
• DNS Response: The IP address is sent back through the chain to your device, allowing your browser to establish a connection with the web server.
• Web Page Retrieval: With the IP address in hand, your browser can communicate directly with the web server hosting the requested website, and the webpage content is retrieved and displayed.

DNS is a crucial part of internet infrastructure that ensures you can access websites using human-readable domain names. Without DNS, you'd need to remember numerical IP addresses for every site you want to visit, which would be highly impractical.