A (IPv4), AAAA (IPv6), CNAME (alias), MX (mail), TXT (verification, SPF, DKIM), NS (authoritative nameservers).

How does DNS resolution work?

Recursive resolver → root servers → TLD servers → authoritative nameserver → record. Cached at every hop; TTL controls staleness.

What's DNS propagation?

Old records persist in caches up to their TTL. 'Propagation' is really just waiting for caches worldwide to expire and re-fetch.

dig (Linux/macOS), nslookup (Windows), and online tools (dns.google, 1.1.1.1). Check authoritative vs cached results to isolate caching issues.

Record types, resolution, debugging, common snags. Part of the DevTools Surf developer suite. Browse more tools in the Info / Guides collection.

The Domain Name System was invented by Paul Mockapetris in 1983 (RFC 882/883), replacing a single HOSTS.TXT file that was manually distributed to every computer on ARPANET.
There are exactly 13 root DNS server addresses (A through M), operated by 12 organizations. Due to anycast, the actual number of physical servers exceeds 1,700.
The maximum length of a fully qualified domain name (FQDN) is 253 characters, and each label (between dots) can be at most 63 characters.

Common record types?: A (IPv4), AAAA (IPv6), CNAME (alias), MX (mail), TXT (verification, SPF, DKIM), NS (authoritative nameservers).
How does DNS resolution work?: Recursive resolver → root servers → TLD servers → authoritative nameserver → record. Cached at every hop; TTL controls staleness.
What's DNS propagation?: Old records persist in caches up to their TTL. 'Propagation' is really just waiting for caches worldwide to expire and re-fetch.
How do I debug?: dig (Linux/macOS), nslookup (Windows), and online tools (dns.google, 1.1.1.1). Check authoritative vs cached results to isolate caching issues.

Record types, resolution, debugging, common snags. Part of the DevTools Surf developer suite. Browse more tools in the Info / Guides collection.

The Domain Name System was invented by Paul Mockapetris in 1983 (RFC 882/883), replacing a single HOSTS.TXT file that was manually distributed to every computer on ARPANET.
There are exactly 13 root DNS server addresses (A through M), operated by 12 organizations. Due to anycast, the actual number of physical servers exceeds 1,700.
The maximum length of a fully qualified domain name (FQDN) is 253 characters, and each label (between dots) can be at most 63 characters.

Common record types?: A (IPv4), AAAA (IPv6), CNAME (alias), MX (mail), TXT (verification, SPF, DKIM), NS (authoritative nameservers).
How does DNS resolution work?: Recursive resolver → root servers → TLD servers → authoritative nameserver → record. Cached at every hop; TTL controls staleness.
What's DNS propagation?: Old records persist in caches up to their TTL. 'Propagation' is really just waiting for caches worldwide to expire and re-fetch.
How do I debug?: dig (Linux/macOS), nslookup (Windows), and online tools (dns.google, 1.1.1.1). Check authoritative vs cached results to isolate caching issues.