ESXi hypervisor is the same as any other server or network device, so you need to take into account the configuration backup. While the installation only takes a couple of minutes, the backup contains configuration files concerning virtual switches and their configuration, shared storage (datastore configurations), multi-paths, local users and groups, and also licensing information.
This is why you should perform regular backups of your ESXi infrastructure. If something goes wrong, you can install a new ESXi hypervisor and restore the configuration to get the desired state within the blink of an eye.
