What additional security measure can be required for client integrity in SMA?

The correct answer highlights the use of a virtual keyboard as an additional security measure for client integrity in SonicWall Secure Mobile Access (SMA). Implementing a mandatory virtual keyboard helps protect against keylogging and other forms of input monitoring. By requiring users to interact with a virtual interface for entering sensitive information, the risk of capturing keystrokes through malware or spyware installed on the local device is significantly reduced. This measure ensures that critical data, such as passwords or personal identification numbers, remains secure during transmission and is not compromised by external threats.

Other options may contribute to overall network security or user access policies but do not specifically enhance client integrity in the same way. For example, using VPN services provides encryption and secure tunneling for connections but does not directly address input vulnerabilities. Relying solely on wired connections limits mobility and does not incorporate protection against client-side threats. Setting a password expiration date is an essential security practice but focuses on account security rather than protecting the client's interaction with the system, which is where the virtual keyboard becomes particularly relevant.