DNS (Domain Name System)
The internet's system for translating human-readable domain names into IP addresses.
Definition
DNS functions as the internet's phone book, converting domain names like "example.com" into IP addresses that computers use to locate servers. When you type a URL, DNS servers resolve the name to an IP address before your browser can load the page.
DNS configuration includes A records, CNAME records, MX records for email, and TXT records for verification.
Why It Matters
DNS misconfiguration can make websites unreachable. Understanding DNS helps troubleshoot connectivity issues and implement features like subdomains and email routing.
DNS propagation delays—the time for changes to spread globally—affects website migrations and launches.
Examples in Practice
A company migrates to a new host by updating their A record to point to the new server's IP address.
DNS TTL settings are lowered before a migration to speed up propagation of the upcoming change.
An email deliverability issue is traced to missing SPF and DKIM DNS records.