Cisco pxGrid is used to enable the sharing of contextual-based information from which devices?

Cisco pxGrid (Platform Exchange Grid) is designed to facilitate the sharing of contextual information between various security solutions and network devices. It allows different systems to communicate by sharing relevant information such as user identity, device posture, and network context, which enhances the overall security posture of the network.

The correct choice focuses on the interaction between a Cisco Identity Services Engine (ISE) session directory and other policy network systems. Cisco ISE serves as a central point for identity and access policy management, collecting and storing information about devices and users on a network. By leveraging pxGrid, Cisco ISE can share this contextual information with a variety of other Cisco devices, such as those running Cisco IOS, firewalls like the Cisco ASA, and various security applications. This sharing is essential for enforcing policies based on the context derived from user sessions, aiding in incident response and improving overall security.

In summary, option D accurately describes the primary function of pxGrid, where it facilitates the sharing of context from the Cisco ISE session directory to various policy network systems, enhancing integrated security workflows.