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DNS Architecture & Design

Domain Name System protocol, resolver architecture, caching strategies, and distributed design patterns

80 minutes
8Detailed Sections
Senior Level

DNS (Domain Name System) translates human-readable domain names (example.com) to IP addresses (93.184.216.34).

Why DNS exists: humans remember names better than numbers; IP addresses can change without affecting domain names; enables content distribution, load balancing, and failover.

DNS hierarchy: Root servers (13 sets worldwide, operated by organizations like Verisign, NASA, US DoD), TLD servers (.com, .org, .net managed by registries), authoritative servers (your domain nameserver).

Query flow: client asks resolver -> resolver queries root -> root directs to TLD -> TLD directs to authoritative -> authoritative returns IP.

Record types: A (IPv4), AAAA (IPv6), CNAME (alias), MX (mail), TXT (text, used for verification), NS (nameserver), SOA (start of authority).

Real-world: Google Public DNS (8.8.8.8) handles billions of queries; Cloudflare (1.1.1.1) offers privacy-focused DNS; AWS Route 53 provides managed DNS at scale.

Key Takeaways

1
DNS Purpose: Translate domain names to IP addresses; enables human-friendly naming
2
Hierarchy: Root servers (13) -> TLD (.com, .org) -> Authoritative (your domain)
3
Query Flow: Client -> Resolver -> Root -> TLD -> Authoritative -> IP returned
4
Record Types: A (IPv4), AAAA (IPv6), CNAME (alias), MX (mail), TXT, NS, SOA
5
Distributed System: 13 root server clusters, millions of authoritative servers globally
6
Real-world: Google DNS (8.8.8.8), Cloudflare (1.1.1.1), AWS Route 53

Visual Diagram

Client -> Resolver -> Root -> TLD (.com) -> Authoritative (example.com) -> IP
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