Domain Name System (DNS)
The Domain Name System (DNS) is the phonebook of the Internet. Humans access information online through domain names, like nytimes.com or espn.com. Web browsers interact through Internet Protocol (IP) addresses. DNS translates domain names to IP addresses so browsers can load Internet resources.
Record Types: 1. A (IPv4). 2. AAAA (IPv6). 3. CNAME (Alias). 4. MX (Mail). 5. TXT (Metadata/Verification). Ports: UDP/TCP 53, HTTPS 443 (DoH), TLS 853 (DoT).
graph LR
Center["Domain Name System (DNS)"]:::main
Rel_oracle["oracle"]:::related -.-> Center
click Rel_oracle "/terms/oracle"
Rel_delegated_proof_of_stake["delegated-proof-of-stake"]:::related -.-> Center
click Rel_delegated_proof_of_stake "/terms/delegated-proof-of-stake"
Rel_internet_of_things_iot["internet-of-things-iot"]:::related -.-> Center
click Rel_internet_of_things_iot "/terms/internet-of-things-iot"
classDef main fill:#7c3aed,stroke:#8b5cf6,stroke-width:2px,color:white,font-weight:bold,rx:5,ry:5;
classDef pre fill:#0f172a,stroke:#3b82f6,color:#94a3b8,rx:5,ry:5;
classDef child fill:#0f172a,stroke:#10b981,color:#94a3b8,rx:5,ry:5;
classDef related fill:#0f172a,stroke:#8b5cf6,stroke-dasharray: 5 5,color:#94a3b8,rx:5,ry:5;
linkStyle default stroke:#4b5563,stroke-width:2px;
🧒 Explain Like I'm 5
Imagine the internet is a giant city, and every website is a house. Instead of remembering the exact map coordinates for every house, you just use a phonebook. You look up 'Joe's Pizza', and the phonebook tells you it's at '123 Main Street'. [DNS](/en/terms/dns) is that giant, automatic phonebook for the whole internet.
🤓 Expert Deep Dive
Technically, a DNS query follows a 'Recursive' path. 1. Your device asks the 'Recursive Resolver' (usually your ISP or 1.1.1.1). 2. The resolver asks the 'Root Server'. 3. The Root points to the 'TLD Server' (.com). 4. The TLD points to the 'Authoritative Nameserver'. 5. The Authoritative server provides the actual record (e.g., an 'A Record' for IPv4). To speed this up, DNS relies heavily on 'Caching'—storing results for a period determined by the 'TTL' (Time To Live). Modern DNS also includes 'DNSSEC'—a set of security extensions that use digital signatures to verify that the DNS data hasn't been tampered with. This prevents 'Cache Poisoning' attacks where a hacker redirects you to a fake version of a website.