The Forescout policy engine evaluates all main rules within a policy concurrently against an endpoint. This means they are all processed at the same time to determine if their conditions are met. If a main rule's conditions are met and it contains sub-rules, the sub-rules are then evaluated sequentially, from top to bottom. The first sub-rule whose conditions are met is applied, and the evaluation of subsequent sub-rules under that specific main rule stops. This ensures a predictable, prioritized order for sub-rule application.

B. Main rules process in parallel, sub-rules process concurrently.

Sub-rules are not processed concurrently; they are evaluated sequentially in a specific, top-down order to enforce priority.

C. Main rules process concurrently, sub-rules process in parallel.

Sub-rules are not processed in parallel. Their sequential evaluation is critical for applying the first, most specific match.

D. Main rules process sequentially, sub-rules process concurrently.

Main rules are processed concurrently, not sequentially. Sub-rules are also processed sequentially, not concurrently.

E. Main rules process sequentially, sub-rules process in parallel.

This is incorrect on both counts. Main rules are concurrent, and sub-rules are sequential.

1. Forescout Administration Guide, Version 8.2. Section: "Policy Components and Logic," Subsection: "How Policies Are Evaluated." The guide states, "All main rules in a policy are evaluated concurrently... If a main rule has sub-rules, the sub-rules are evaluated sequentially from top to bottom. The first sub-rule that matches the endpoint is applied." This directly supports the concurrent nature of main rules and the sequential nature of sub-rules.

2. Forescout Policy and Rule Creation Courseware (FSCE). Module: "Policy Structure and Evaluation." The official training material explains that the policy engine is designed for efficiency by checking all primary (main) conditions simultaneously. It then explicitly details the top-down, first-match logic for sub-rules, defining it as sequential processing.