DNS RESOLUTION JOURNEY Iterative Hierarchy & Multi-Tier TTL Caching

Browser -> OS Stub -> Recursive Resolver -> Root (.) -> TLD (.com) -> Authoritative Name Server

Step 1 / 10

UDP/53 DNS Query Referral / A-Record Reply NXDOMAIN Negative Cache

Stage 1: Hierarchy Overview TTL: 300s

1. The DNS Hierarchy

Why This Matters

Multi-tier TTL caching keeps 95%+ of DNS lookups local while iterative referrals distribute global namespace authority across Root, TLD, and Authoritative zones.

Active Query Context example.com -> 192.0.2.1

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Recursive Resolver

Iterative ISP / 1.1.1.1

State: READY (iterative-walk)

Receives recursive queries from OS stub resolvers and performs iterative lookups across Root (.), TLD (.com), and Authoritative servers.

Runtime Config Controls in:0 out:0 · 12ms

Inputs

UDP/53 Stub Query

Outputs

Cached A Record

Telemetry Signals