Scanning is the process in which attributes of a set of hosts, virtual machines, or virtual appliances are evaluated against all patches, extensions, and upgrades from an attached baseline or baseline group, depending on the type of scan you select.

You can scan a host installation to determine whether the latest patches or extensions are applied, or you can scan a virtual machine to determine whether it is up to date with the latest virtual hardware or VMware Tools version.

Update Manager supports the following types of scan:
Host patch scan
You can perform patch scans on ESXi 5.5 and later.
Host extensions scan
You can scan ESXi 5.5 and later for extensions (additional software modules).
Host upgrade scan
You can scan ESXi 5.5 and ESXi 6.0 for upgrading to ESXi 6.5.
VMware Tools scan
You can scan virtual machines running Windows or Linux for the latest VMware Tools version. You can perform VMware Tools scans on online or offline virtual machines and templates. You must power on the virtual machine at least once before performing a VMware Tools scan.
Virtual machine hardware upgrade scan
You can scan virtual machines running Windows or Linux for the latest virtual hardware supported on the host. You can perform hardware-upgrade scans on online or offline virtual machines and templates.
Virtual appliance upgrade scan
You can scan powered-on virtual appliances that are created with VMware Studio 2.0 and later.

You can use VMware Studio 2.0 and later to automate the creation of ready-to-deploy vApps with pre-populated application software and operating systems. VMware Studio adds a network agent to the guest so that vApps bootstrap with minimal effort. Configuration parameters specified for vApps appear as OVF properties in the vCenter Server deployment wizard. For more information about VMware Studio, see the VMware SDK and API documentation for VMware Studio. For more information about vApp, you can also check the VMware blog site. You can download VMware Studio from the VMware website.

You can initiate scans on container objects, such as data centers, clusters, vApps, or folders, to scan all the ESXi hosts or virtual machines and appliances in that container object.

You can configure Update Manager to scan virtual machines, virtual appliances, and ESXi hosts against baselines and baseline groups by manually initiating or scheduling scans to generate compliance information. Schedule scan tasks at a data center or vCenter Server system level to make sure that scans are up to date.

For manual and scheduled scanning procedures, see Scanning vSphere Objects and Viewing Scan Results.