What is the main restriction regarding the SSL trust package configuration on ProxySG?

The correct answer highlights that the ProxySG accepts only trust packages from Blue Coat. This restriction is important because it ensures a consistent and secure framework for handling SSL/TLS traffic and establishing trust within the proxy environment. By using trust packages exclusively from Blue Coat, users can be assured that they meet the required standards and compatibility for secure communications.

This approach simplifies management and minimizes potential vulnerabilities. Trust packages are essential for verifying that SSL certificates presented by servers are legitimate and not associated with potential security risks. Relying solely on packages from Blue Coat also streamlines troubleshooting and support, as all components are designed to work seamlessly within the Blue Coat ecosystem.

The other options suggest varying degrees of flexibility that are not available in the ProxySG's SSL trust package configuration. For instance, allowing any SSL trust package or enabling third-party packages could introduce compatibility issues and increase the risk of interception by malicious entities. Additionally, the ability to load multiple packages could complicate the trust hierarchy and certificate validation process, leading to potential security vulnerabilities. Thus, sticking to Blue Coat’s validated trust packages is a crucial measure for maintaining robust security.