DNS (Domain Name System) is a hierarchical, distributed naming system that converts domain names into IP addresses and stores other service records. It's the internet's address book, allowing you to type a domain name instead of memorizing numeric IP addresses.
How it works
When you visit a website, your device (stub resolver) queries a recursive resolver, which then follows a chain of referrals: root servers → top-level domain servers → authoritative name servers for that domain. Each step returns the answer or a pointer to the next step. The recursive resolver caches the result and returns it to you.
DNS data is stored as Resource Records (RRs) — these include A records for IPv4 addresses, AAAA records for IPv6, MX records for email routing, CNAME records for aliases, TXT records for verification, and many others.
Key details
DNS queries use UDP port 53 by default, with TCP as a fallback for larger responses or zone transfers. Each record includes a TTL (Time To Live) value that controls how long resolvers cache it before re-querying.
Because DNS is distributed and cached, changes don't propagate instantly worldwide — DNS propagation can take hours or longer as different resolvers' caches expire.
For security, DNSSEC adds cryptographic signatures to verify authenticity. Use our DNS lookup tool to inspect records for any domain.
TipKeep your authoritative DNS in one place so records, TTLs and DNSSEC stay consistent — zones scattered across providers are the most common source of drift.