Windows 7 / Getting Started

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Driver Ranking

Windows XP uses the following algorithm to arbitrate between several possible drivers when installing a device:

1. In-box drivers are given first preference.
2. Windows Hardware Quality Labs (WHQL)-signed drivers are given next preference, with the most recent driver preferred.
3. Unsigned drivers are given lowest preference, with the most recent driver preferred.

Windows Vista and later versions support the following eight levels of digital signature, listed in order of decreasing preference:

1. Microsoft-signed WHQL-Certified drivers
2. Microsoft-signed in-box drivers (NT Build Lab Certified)
3. Microsoft-signed WinSE-Certified drivers
4. Drivers that have been signed using Authenticode (Enterprise CA)
5. Drivers that have been signed using Authenticode (Class 3 CA Certified)
6. Drivers that have been signed using Authenticode (MAKECERT.EXE Certified)
7. Microsoft-signed WHQL-Certified drivers for a previous version of the Windows operating system
8. Unsigned drivers

Note For the purpose of calculating rank, WHQL, DQS, INBOX, STANDARD, and PREMIUM are all equal for both Windows XP and Windows Vista.

In addition to if (and how) drivers are signed, Windows Vista and later versions use the following criteria to determine which version of a driver should be installed for a particular device:

• The value of the feature score specified in the driver INF file if one is provided
• How closely the Plug and Play ID (PNPID) of the device matches the PNPID of the driver
• How recent is the driver compared to other suitable drivers
• The driver version

Note Date and version are considered only if every other aspect of the driver rank is equal-such as signed/unsigned, same hardware ID match, and so on.

For WDDM display drivers, the driver arbitration algorithm is more complex, including the following:

1. WHQL or in-box driver
2. WHQL-Certified or Authenticode-signed driver for an earlier version of the Windows operating system
3. Unsigned driver
4. WDDM driver preferred over any other technology
5. Device ID
6. Driver date
7. Driver version

Note Driver arbitration for audio devices and printers follows a similar algorithm to that used for WDDM display drivers.

Although the default driver-ranking process favors Microsoft-signed drivers over Authenticode- signed drivers, you can modify this behavior by configuring the following Group Policy setting:

Computer Configuration\Policies\Administrative Templates\System\Device Installation \Treat All Digitally Signed Drivers Equally In The Driver Ranking And Selection Process

For more information, see the section titled "Managing Device Installation Behavior" later in this tutorial.