What Is an X.500 Directory?

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X.500 is an ITU-U standard that directory services can make use of. An X.500 directory service has a top-down tree-like structure called a domain tree . At the top of the tree is the root, and below that are forests and trees.

Note

The X.500 directory service standard is a set of directory service standards covering electronic directory services such as white pages, Knowbot, and Whois.

Figure 11.1 shows a sample tree. The root of the tree is Web Widgets Inc. It contains two forests ”Web Widgets UK and Web Widgets US. In the Web Widgets UK forest are the trees Whitby and Stockport.

Figure 11.1. A sample X.500 directory structure.

An X.500 directory is then broken up into organizational units (OUs). As you can see in Figure 11.1, the Whitby tree contains three OUs ”Sales, Marketing, and Production. An OU acts as a container. Within it are resources such as details on people (users), computers, printers, and so on. The kind of information an X.500 directory holds varies according to the software implementing the directory. For users, for example, you can store items such as name, last name , password, email address, postal address, telephone number, and department. X.500 directories are implemented in various types of software. Here is a partial list of various operating systems and applications:

• Windows 2000 Active Directory

• NetWare

• Netscape Directory Server

• IBM Lotus Notes

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