A pool is a group of origin servers, with each origin identified by its IP address or hostname.
If you are familiar with DNS terminology, think of a pool as a “record set,” except Cloudflare only returns addresses that are considered healthy. You can attach health checks to individual pools for customized monitoring.
Per origin Host header override
The Cloudflare API supports the following commands for pools. Examples are given for user-level endpoint but apply to the account-level endpoint as well.