Problem
Using vSphere clusters (zones) allows IT administrators to aggregate and organize virtualization resources in a VMware environment and tie them back to the underlying physical resources. However, CAPV and DKP are unaware of a vSphere cluster as an entity. That might be problematic if you want to install a DKP cluster using resources only from a given vSphere cluster.
Solution
The solution is to use vSphere resource pools, which CAPV and DKP support. Please see the DKP on vSphere and CAPV documentation for detailed information about resource pools. Please note that, according to the DKP documentation, you must specify the name of the vSphere cluster when you build a VM image.