DNS Resolution
Translate human-readable domain names into IP addresses via a distributed, hierarchical lookup system.
★★★★★5/5Network layer — DNS, CDN, load balancers, routing
Interactive visualization
LiveHow it works
The Domain Name System (DNS) is the internet's phone book. When you type 'google.com', a recursive resolver queries a hierarchy of name servers to find the IP address.
Resolution path: Recursive Resolver → Root Name Server → TLD Name Server (.com) → Authoritative Name Server → IP address returned → cached for TTL.
Key record types: A (domain → IPv4), AAAA (domain → IPv6), CNAME (alias to another domain), MX (mail exchange), TXT (arbitrary text — SPF, DKIM, domain verification), NS (authoritative name servers), SRV (service discovery).
DNS is leveraged for: load balancing (multiple A records), health-based routing (Route 53 health checks), geo-routing (serving nearest region), and CDN edge selection.
Why it matters
DNS underpins all internet communication. Understanding DNS is essential for diagnosing outages, configuring services, and designing resilient global routing.
✓ When to use
- →Domain configuration for any public service
- →Global traffic routing and geo-based load balancing
- →Service discovery in microservices via DNS SRV records
✗ When NOT to use
- →DNS is infrastructure — you always use it, but don't 'choose' it for a use case
Trade-offs
Globally distributed, highly available by design
TTL-based caching causes propagation delays during changes
Simple to configure, broadly understood
DNS poisoning / hijacking is a real attack vector
In production
Health-check-based DNS failover routes traffic away from unhealthy regions
1.1.1.1 resolver processes 1 trillion+ queries/day; fastest resolver globally
Industry adoption
Related principles
CDN Architecture
LiveServe content from edge nodes geographically close to users, drastically reducing latency and origin load.
Load Balancing
LiveDistribute incoming traffic across multiple servers to maximise throughput, minimise latency, and prevent overload.
OSI Model
Seven-layer conceptual model for how network communication is structured — from physical bits to application data.