Glossary · Definition
DNS
DNS (Domain Name System) is the internet's distributed phonebook — it translates human-readable domain names like 'freetoolarena.com' into the IP addresses servers actually use. Every browser request starts with a DNS lookup.
Definition
DNS (Domain Name System) is the internet's distributed phonebook — it translates human-readable domain names like 'freetoolarena.com' into the IP addresses servers actually use. Every browser request starts with a DNS lookup.
What it means
When you type a URL, your operating system asks a DNS resolver (your ISP, 1.1.1.1, 8.8.8.8) to find the IP for the domain. If the resolver doesn't have it cached, it walks the authoritative chain: root nameservers → TLD nameservers (.com, .io) → the domain's registered nameservers → the actual record. Common record types: A (IPv4), AAAA (IPv6), CNAME (alias to another domain), MX (mail server), TXT (verification, SPF, DKIM), NS (delegation). Every record has a TTL — how long resolvers may cache it — typically 300-3600 seconds.
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Why it matters
DNS is the layer where domain ownership, deployment, and email plumbing all meet. Switching hosts means updating A/CNAME records and waiting for TTLs to expire. Setting up email needs MX, SPF (TXT), DKIM (TXT), DMARC (TXT). Adding a CDN often means CNAME-ing your apex to the CDN. DNS misconfiguration is the most common cause of 'site is down' for hours after a deploy. DNSSEC adds cryptographic signatures so resolvers can verify records weren't tampered with — adoption is partial but growing.
Frequently asked questions
How long does DNS propagation take?
As long as the highest TTL on any cached record. Most resolvers refresh within an hour for low-TTL records; some misbehaving caches can hold for a day. Lower TTLs to 60-300s before planned migrations.
What's the difference between A and CNAME?
A points directly at an IP address. CNAME points at another domain (which itself resolves further). You can't put a CNAME at the apex (root) of a domain — use ALIAS or ANAME at registrars that support it, or A records.
1.1.1.1 vs 8.8.8.8?
Public DNS resolvers from Cloudflare and Google respectively. Both are faster than typical ISP DNS and don't log your queries (Cloudflare also encrypts queries via DoH/DoT).
Related terms
- DefinitionCDNA CDN (Content Delivery Network) is a globally distributed network of edge servers that cache your site's static content (HTML, CSS, JS, images, fonts) close to users so each request hits a nearby PoP instead of your origin server.
- DefinitionHTTPSHTTPS is HTTP wrapped in a TLS-encrypted tunnel. Everything between your browser and the server — URLs, form data, cookies, response bodies — is encrypted in transit so a network observer (cafe Wi-Fi, ISP, anyone in between) can't read it or change it.