Build a proxmox cluster and teach yourself about high availability services. Tear it down and do it again with xcp-ng. Repeat using more and more complex architectures

First non negative integer so easy for computer to display.

I only really use zero in networking names to correspond with an IPv4 address that ends with dot zero.

I think it’s just what you’re used to. Like counting bottom to top in teleco versus counting top to bottom in IT.