A public website using round robin DNS is an example of:

Round-robin DNS works by returning multiple A records for the same hostname in rotating order, so successive client queries receive different IP addresses pointing to different servers. This distributes the incoming request load across a pool of servers without requiring dedicated hardware load balancers. It is one of the simplest DNS-based load balancing techniques used for public-facing websites.

QoS (Quality of Service) prioritizes specific types of network traffic to manage bandwidth and latency, and does not distribute requests across multiple servers.

Caching engines store frequently requested content closer to the user to reduce origin server load, which is a different mechanism from distributing DNS-based requests.

Traffic shaping controls the rate and flow of network traffic to enforce bandwidth policies, and is not related to distributing DNS queries across multiple hosts.