Introduction to Domain Name System
If you have ever registered a domain or made a website live, then you have interacted with the Domain Name System (DNS). The Domain Name System is a hierarchical decentralized naming system that maps human-readable domain names to IP addresses, which identifies a server and its location in the network.
What is DNS and How Does it Work?
When you type a website name (domain name) in the browser’s address bar, the computer sends a query to the local DNS resolver. The resolver checks its cache (memory) to see if the IP address for that domain name is cached. If the IP address is not cached, the resolver sends a query to the internet root servers to find the authoritative DNS server for the top-level domain (TLD) of the website’s name.
After the authoritative DNS server is located, the resolver queries the authoritative DNS server to receive the IP address for the website’s name. Once the IP address is retrieved, the DNS resolver caches it and returns it to the computer, which sends a request to the IP address to establish a connection and load the website.
Expired Domains and DNS
When a domain name expires, the DNS records for that domain are deleted from the authoritative DNS servers. This means that the IP address and hostname of the expired domain are no longer accessible via DNS.
However, the deleted DNS records can still be accessed via the DNS cache of computers that previously accessed the website. Expired domains that still have cached DNS records can be re-registered by anyone who knows how to access the cache and replicate the DNS records.
Conclusion
The Domain Name System is an integral part of the internet that makes it possible for users to easily access websites using human-readable domain names. Expired domains, which have lost their DNS records, can still be re-registered by accessing the cached DNS records on computers that previously accessed the website. Understanding how DNS works can help you in the process of domain registration and management.