juniornetworking
Browser -> DNS resolver -> root -> TLD -> authoritative NS -> IP address.
DNS resolves domain -> IP. Chain: browser cache -> OS cache -> Recursive resolver (ISP) -> Root NS (.com) -> TLD NS -> Authoritative NS -> IP. TTL determines caching duration. In system design: DNS-based load balancing (Route 53), GeoDNS for multi-region, low TTL for fast failover.
When yes
Global load balancing, multi-region, failover strategies
When no
Internal service discovery (use service mesh or Consul)
Interview tip
DNS is the first hop. Start system design with 'client enters URL -> DNS -> ...'
Alt:Service Discovery (Consul, Eureka)Service Mesh (Istio)