DNS
Domain Name System — the distributed directory that resolves human-readable domain names (example.com) to IP addresses (203.0.113.42) and makes the entire internet navigable.
The Domain Name System (DNS) is the phone-book layer of the internet: every browser, app and mail server first asks a DNS resolver which IP address belongs to a hostname. Resolution runs hierarchically: root servers → TLD servers (.com, .org) → the domain's nameservers → final answer. Important record types: A (IPv4 address), AAAA (IPv6), CNAME (alias to another domain), MX (mail exchanger), TXT (free text, often for SPF, DKIM, domain verification), NS (responsible nameservers), CAA (which CAs may issue certificates). TTL (Time-to-Live) controls how long resolvers cache an entry — drop the TTL to 300 seconds two days before a migration so the cutover takes effect without delay.
Also known as
Domain Name System
Related terms
Sources
Updated: 16.05.2026