DNS
The phonebook of the internet. Translates human-readable domain names (google.com) into IP addresses that computers understand.
What is DNS?
The phonebook of the internet. Translates human-readable domain names (google.com) into IP addresses that computers understand.
DNS is a foundational concept that sits in the Load Balancing & Proxies area of system design. Engineers reach for it whenever they need to reason about real-world trade-offs in that space — not just for textbook correctness, but because real production systems at companies like Netflix, Amazon, and Google make these decisions every day.
If you want to go deeper than this definition — with diagrams, code, and a quiz to lock it in — work through the "DNS" lesson linked below. It walks through the why, the mechanism, the trade-offs, and how the giants actually use it in production.
Learn DNS in depth
Full interactive lesson with diagrams, code examples, real-world references, and a quiz.
Open the DNS lessonRelated lessons
Lessons that touch on DNS as part of a larger topic.
DNS Load Balancing
Using DNS to distribute traffic across servers, the simplest form of global load balancing
foundation · load balancing proxies
Multi-Value Routing
Return multiple healthy endpoints in a single DNS response for client-side load distribution
foundation · load balancing proxies
Global Server Load Balancing (GSLB)
Distribute traffic across geographically dispersed data centers using DNS and health-aware routing
foundation · load balancing proxies
Anycast Routing
One-to-nearest communication, routing to the closest instance of a service
foundation · load balancing proxies
Geolocation Routing
Route requests to the nearest regional backend based on the client's geographic location
foundation · load balancing proxies
See also
Related glossary terms you might want to look up next.
CDN
A network of servers distributed globally that caches content close to users. Netflix uses CDNs to stream video from servers near you, not from one central location.
Load Balancer
Distributes incoming traffic across multiple servers so no single server gets overwhelmed. Like a traffic cop directing cars to different lanes.
Reverse Proxy
A server that sits in front of your backend servers and forwards client requests to them. Handles SSL termination, caching, and load balancing.