Virtual private networks (VPNs) are commonly used to allow access into trust zones. Via a VPN, access can be controlled and logged and only allowed through secure channels by authorized users. It also adds an additional layer of encryption and protection to communications.

Explanation
Explanation:
An XML firewall is most commonly deployed in line between the firewall and application server to validate XML code before it reaches the application. An XML firewall is intended to validate XML before it reaches the application. Placing the XML firewall between the presentation and application layers, between the firewall and IPS, or between the application and data layers would not serve the intended purpose.

Forensic analysis is the least challenging of the answers provided as it refers to the analysis of data once it is obtained. The challenges revolve around obtaining the data for analysis due to the complexities of international law, the decentralization of data storage or difficulty knowing where to look, and identifying the data owner, controller, and processor.

Explanation
DRM and DLP are used for increased authentication/access control and egress monitoring, respectively, and would actually decrease portability instead of enhancing it.

A reservation is a minimum resource that is guaranteed to a customer within a cloud environment. Within a cloud, a reservation can pertain to the two main aspects of computing: memory and processor. With a reservation in place, the cloud provider guarantees that a cloud customer will always have at minimum the necessary resources available to power on and operate any of their services.