Description of problem:
When installing a cluster on AWS using IPI, the VPC CIDR is created with machine CIDR. And subnet prefixes are ​​created with 4 added to the CIDR of the VPC. But there aren't document about subnet prefix. Is this behavior intended?
 
Version-Release number of selected component (if applicable):
openshift4.2
 
How reproducible:
Steps to Reproduce:
1.edit machineCIDR of install-cinfig.yaml.
ex) 10.105.0.0/20
2. ./openshift-install create cluster
3.confirm the prefix of the private and public subnet.
 
Actual results:
CIDR of private and public subnet is created as 10.105.X.0/24.
If edit machineCIDR to 10.105.0.0/16, CIDR of the private and public subnet are created as 10.105.X.0/20.
If edit machineCIDR to 10.105.0.0/19, CIDR of the private and public subnet are created as 10.105.X.0/23.
Is it the intended behavior? I couldn't find any documentation about this behavior.