Upgrading ESXi Hosts - VMware
docs.vmware.com › en › VMware-vSphereTo upgrade ESXi 5.5 hosts or ESXi 6.0 hosts to ESXi 6.5, you can boot the ESXi installer from a CD, DVD, or USB flash drive. Installing or Upgrading Hosts by Using a Script You can quickly deploy ESXi hosts by using scripted, unattended installations or upgrades. Scripted installations or upgrades provide an efficient way to deploy multiple hosts.