How DNS, IP addresses, and record types work: the core concepts behind every domain lookup, explained step by step.
Three layers share the name "DNS server"
Stub resolver
your own device
Recursive resolver
ISP, router, or 1.1.1.1
Authoritative
the domain's own DNS
Understand domain IP address lookup results, including multiple addresses, IPv4 and IPv6 records, CDN edges, and the limits of reverse attribution.
Three layers share the name "DNS server"
Stub resolver
your own device
Recursive resolver
ISP, router, or 1.1.1.1
Authoritative
the domain's own DNS
Learn what DNS servers do, how recursive resolvers differ from authoritative nameservers, and how to identify which server answered a query.
A recursive DNS lookup, one hop at a time
Browser
wants example.com
Resolver
your ISP / 1.1.1.1
Root + TLD
who runs .com?
Authoritative
the real answer
Every hop down this chain is itself a DNS lookup, cached afterward
Follow a DNS query through caches, recursive resolvers, referrals, and authoritative servers to understand how a hostname becomes an address.
The records you will meet in nearly every zone
Understand the DNS SOA record, its serial number, refresh and retry timers, and how it helps authoritative nameservers coordinate a zone.
Three roles, often three different companies
Understand NS records, parent-zone delegation, authoritative nameservers, and how to confirm which DNS provider serves a domain's records.
The records you will meet in nearly every zone
Learn how DNS zone files organize records, owner names, TTLs, and record data, with a safe checklist for reviewing or migrating a zone.
Two addressing schemes, running side by side
IPv4
192.0.2.10
32 bits -- ~4.3 billion addresses -- exhausted
IPv6
2606:4700::6810:84e5
128 bits -- 340 undecillion addresses
Compare static and dynamic IP addresses, learn where each is used, and understand why domain DNS records should not be confused with a fixed address.
The records you will meet in nearly every zone
Every record type worth knowing, what it does, what it looks like, and the mistake people make with it — in one reference page.
Three reasons the same domain answers differently
Geo-routing
A different edge server per region
Caching
Independent TTLs, independent caches
Split-horizon
A different answer, by design
Learn how IP geolocation estimates network location, why results can differ from a user's physical location, and what a DNS lookup can actually tell you.
The records you will meet in nearly every zone
Learn how wildcard DNS records match otherwise-unconfigured names, when they simplify subdomain management, and how they can hide mistakes.
A CNAME aliases a name, not an address
www.example.com
CNAME record
cdn.provider.net
target hostname
192.0.2.10
A record, final answer
Understand how CNAME records create alias chains, how resolvers reach A and AAAA addresses, and what to check when a chain breaks.
Picking a TTL in practice
Copy-paste commands for every platform — and the diagnostic that tells you whether flushing will help before you bother.