You can apply a customization spec to an existing virtual machine. Using customization specs helps prevent conflicts that can result if you deploy virtual machines with identical settings, such as duplicate computer names.

When you clone an existing virtual machine, or deploy a virtual machine from a VM template in a folder, you can customize the guest operating system of the resulting virtual machine during the clone or the deployment tasks.

When you deploy a virtual machine from a template in a content library, you can customize the guest operating system only after the deployment task is complete.


  • Verify the guest operating system is installed.
  • Verify that VMware Tools is installed and running.
  • Power off the virtual machine.


  1. Right-click a virtual machine in the vSphere inventory, and select Guest OS > Customize Guest OS.
    The Customize Guest OS dialog box opens.
  2. Select a customization specification from the list and click OK.
    If the specification requires you to configure additional settings, a new dialog box opens and your are prompted to enter information about the required settings.