CACHING
Tiered Cache
The default problem
With no tiering, every colo that misses dials origin directly — hundreds of front doors hammering one back door.
The mechanism
Colos are ranked into lower and upper tiers; a lower-tier miss asks an upper tier before anyone bothers origin.
The result
A higher hit ratio, far less origin traffic, and warmer copies held closer to origin.
Cloudflare Application Performance11