What is DNS?

The Domain Name System turns names people remember, like example.com, into the IP addresses computers use. It is the internet's distributed phone book.

What happens when you open a website

1. Your device asks a recursive resolver, usually your provider's or a public one such as 1.1.1.1 or 8.8.8.8.
2. If the answer is not cached, the resolver asks a root server, which points to the servers for the top-level domain (.com).
3. The .com servers point to the domain's authoritative name servers (its NS records).
4. The authoritative server returns the record, say an A record with the IP address, and the resolver caches it for its TTL.

All of this usually takes a few milliseconds, and cached answers are nearly instant.

Main record types

• A / AAAA: IPv4 / IPv6 address of the name.
• CNAME: alias to another name (cannot coexist with other records on the same name).
• MX: mail servers for the domain.
• TXT: text records for SPF, DKIM, DMARC and domain verification.
• NS: which servers are authoritative for the domain.
• CAA: which certificate authorities may issue certificates.

See any domain's records with the DNS lookup.

Common DNS problems

• DNS_PROBE_FINISHED_NXDOMAIN / "server not found": the name does not exist. Check the spelling, the domain's registration and its NS records.
• Changes not visible: old answers are cached until their TTL expires. Wait, or flush your local cache (ipconfig /flushdns on Windows).
• Email going to spam: missing or wrong SPF, DKIM or DMARC TXT records.
• Slow first load: a slow resolver. Switching your device or router to a fast public resolver often helps.

Is DNS private?

Classic DNS travels unencrypted, so your network operator can see which names you look up. DNS-over-HTTPS (DoH) and DNS-over-TLS (DoT) encrypt those queries; modern browsers and operating systems support both.