Which component is used to obtain identification and security information about network users?

The correct choice is the User Directory, as it serves as a critical repository for obtaining identification and security information about network users. The User Directory typically integrates various sources of user information, such as directories from Active Directory, LDAP, or local databases, accumulating details like user accounts, group memberships, and security attributes. This allows administrators to manage user access and permissions effectively within the network security framework.

In contrast, other options involve different functionalities. A User Index may refer to a listing or mapping of users, but it does not actively provide security information or identification. UserCheck is a feature that helps engage users in security policy compliance and is not focused on data retrieval regarding user identities. Lastly, a User Server may refer to a server that facilitates user-related services but does not specifically act as a centralized source for user identification and security information. Thus, the User Directory is distinctly designed to collect and manage critical user information effectively.