DNS (Domain Name System)
DNS is the system that translates human-readable domain names like example.com into the numerical IP addresses that computers use to locate and connect to web servers.
The Domain Name System (DNS) is often called the "phone book of the internet." Just as a phone book translates a person's name to their phone number, DNS translates domain names (like google.com) to IP addresses (like 142.250.80.46) that computers use to find each other on the internet. When you type a website address in your browser, a series of DNS lookups happen almost instantly.
If none of these have the answer, the query travels through the DNS hierarchy: root servers, top-level domain servers (like .com), and finally the authoritative nameserver for the specific domain. DNS records come in several types.
In practice
- A company switched from their domain registrar's default DNS to Cloudflare's DNS and saw a 40ms improvement in DNS resolution time globally
- A business lost all email for three days because a DNS migration accidentally deleted their MX records; understanding DNS would have prevented this
- A startup uses DNS-based failover: if their primary server goes down, DNS automatically routes traffic to a backup server within 60 seconds
- A global SaaS company uses GeoDNS to route users to the nearest data center: US users hit US servers, European users hit EU servers, reducing latency by 100-200ms
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