Network documentation is the backbone of any good environment, I use Netbox to document both my virtual network/subnet/vlan space as well as the physical layout of infrastructure.

All vlans, subnets, devices, and IPs are documented here. I have some basics for switch infrastructure in as well so that it can be referenced for network automation. This is critically important as we talk about the next portion. Automation

Netbox is my network source-of-truth, what this means is application that I pull facts from it in Ansible playbooks to help configure my switches/equipment/VMs. It is critically important that data in Netbox is correct or the automation will apply borked configurations.