The problem DNS solves
Computers use numerical IP addresses. Humans remember names. DNS bridges this gap with a distributed hierarchical database mapping names to addresses.
The DNS hierarchy
Root servers at the top delegate to TLD servers (.com, .org, .in), which delegate to authoritative servers for each specific domain.
A lookup, step by step
DNS record types
A (IPv4), AAAA (IPv6), CNAME (alias), MX (mail), TXT (SPF, DKIM), NS (name server).
DNS security
Plain DNS is unencrypted. DNSSEC adds signatures. DNS over HTTPS (DoH) and DNS over TLS (DoT) encrypt the full lookup.
