Custom properties are name-value pairs used to specify attributes of a machine or to override default specifications.

Different custom properties are used for different provisioning methods, types of machines, and machine options. Custom properties can be used as described in the following examples:

Specify a particular type of guest OS, for instance Windows 7 64-bit

Enable WIM-based provisioning, in which a Windows Imaging File Format (WIM) image of a reference machine is used to provision new machines

Customize the behavior of Remote Desktop Protocol when connecting to a machine

Register a virtual machine with a XenDesktop Desktop Delivery Controller (DDC) server

Customize a virtual machine’s system specifications, such as adding multiple hard disk drives

Customize the guest OS for a machine, for instance, by including specified users in selected local groups

Enable cleanup of a the Active Directory account of a machine after it is destroyed

Specifying the characteristics of the machines to be provisioned is generally done by adding properties to blueprints and build profiles. You can make custom properties available to multiple blueprints and all business groups by placing them in build profiles.

Any property specified in a blueprint overrides the same property specified in the incorporated build profile. This enables a blueprint to use most of the properties in a profile while differing from the profile in some limited way. For more information, see Order of Precedence for Custom Properties..

For example, a blueprint that incorporates a standard developer workstation profile might override the US English settings in the profile with UK English settings. On the other hand, if no appropriate profile is available all the needed properties can be specified in the blueprint itself. This arrangement ensures that the number and complexity of blueprints remain manageable.

At new machine request time, vCloud Automation Center has not yet allocated a reservation and the compute resource and endpoint are unknown as well. Therefore, only custom properties from a build profile, blueprint and business group are reconciled and presented when the machine is requested.