Why it matters

DNS underlies every internet interaction. Understanding lookup flow, caching, and record types is basic ops knowledge.

Advertisement

The architecture

Hierarchy: root → TLD (com, org) → authoritative for domain → subdomain records.

Records: A (IPv4), AAAA (IPv6), CNAME (alias), MX (mail), TXT (arbitrary), NS (nameserver).

DNS hierarchyRoot13 root serversTLD serverscom, org, net...Authoritative NSdomain-specificRecursive resolvers do the walking; caching at every layer keeps lookups fast
DNS lookup structure.
Advertisement

How it works end to end

Resolution: client asks recursive resolver. Resolver walks hierarchy if not cached, returns IP.

Caching: TTLs control how long records cached. Balance freshness vs load.

Split DNS: internal vs external views. Different records for internal clients.

DNSSEC: cryptographic signing of records. Prevents spoofing.