What Is DNS? Domain Name System Explained
The Domain Name System (DNS) is the internet's distributed address book. It translates human-readable domain names (example.com) into the numeric IP addresses (93.184.216.34) that computers use to route traffic. Without DNS, every user would need to memorise IP addresses.
How DNS Resolution Works
When you visit example.com, your browser checks its local cache. If not found, it queries your OS resolver, then your ISP's recursive resolver. The recursive resolver asks a root nameserver which TLD nameserver (.com) to contact, then the TLD nameserver for example.com's authoritative nameserver, which finally returns the IP address. This full lookup takes ~100 ms; cached lookups are near-instant.
Common DNS Record Types
A record: domain → IPv4. AAAA: domain → IPv6. CNAME: domain → another domain (canonical name alias). MX: mail server for the domain. TXT: arbitrary text — used for SPF (email anti-spoofing), DKIM, site verification. NS: authoritative nameservers for the domain. TTL (Time to Live) controls how long resolvers cache each record.
DNSSEC and DNS over HTTPS
DNSSEC cryptographically signs DNS records, preventing cache poisoning attacks where an attacker injects a false IP. DNS over HTTPS (DoH) and DNS over TLS (DoT) encrypt DNS queries, preventing ISPs or networks from seeing or tampering with your DNS lookups. Major public resolvers (Cloudflare 1.1.1.1, Google 8.8.8.8) support both.