Brief Description on Windows NT Registry

What is Registry?

The windows registry provides for a somewhat secure, unified database that stores configuration information into a hierarchical model. Until recently, configuration files such as WIN.INI were the only way to configure windows applications and operating system functions. In today's NT 4 environment, the registry replaces these .INI files. Each key in the registry is similar to bracketed headings in an .INI file.

To view the registry of an NT server, one would use the Registry Editor tool. There are two versions of Registry Editor: 

Regedt32.exe has the most menu items and more choices for the menu items. You can search for keys and subkeys in the registry. 

Regedit.exe enables you to search for strings, values, keys, and subkeys and export keys to .reg files. This feature is useful if you want to find specific data. 

For ease of use, the Registry is divided into five separate structures that represent the Registry database in its entirety. These five groups are known as Keys.

In Depth Key Discussion

HKEY_CURRENT_USER

This registry key contains the configuration information for the user that is currently logged in. The user’s folders, screen colors, and control panel settings are stored here. This information is known as a User Profile.

HKEY_USERS

In windows NT 3.5x, user profiles were stored locally (by default) in the systemroot\system32\config directory. In NT4.0, they are stored in the systemroot\profiles directory. User-Specific information is kept there, as well as common, system wide user information.

HKEY_LOCAL_MACHINE

This key contains configuration information particular to the computer. This information is stored in the systemroot\system32\config directory as persistent operating system files, with the exception of the volatile hardware key.

The information gleaned from this configuration data is used by applications, device drivers, and the Windows NT 4 operating system. The latter usage determines what system configuration data to use, without respect to the user currently logged on. For this reason the HKEY_LOCAL_MACHINE registry key is of specific importance to administrators who want to support and troubleshoot NT 4.

HKEY_CLASSES_ROOT

The information stored here is used to open the correct application when a file is opened by using Explorer and for Object Linking and Embedding. It is actually a window that reflects information from the HKEY_LOCAL_MACHINE\Software subkey. 

HKEY_CURRENT_CONFIG

The information contained in this key is to configure settings such as the software and device drivers to load or the display resolution to use. This key has a software and system subkeys, which keep track of configuration information.

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