Comprehensive and Detailed Explanation From Exact Extract of Forescout Platform Administration and Deployment:

According to the Forescout Administration Guide and RADIUS Plugin Configuration Guide, the best practice for ordering sub-rules is that the first rule should capture the lowest number of endpoints.​

Sub-Rule Evaluation Order:

According to the documentation:​

"Endpoints are inspected against each sub-rule in the order listed. When an endpoint matches a sub-rule, subsequent sub-rules are not evaluated for that endpoint."

This sequential evaluation means that sub-rule order is critical to policy behavior.

Best Practice - Specific to General:

According to the guidelines:​

The correct approach is to order sub-rules from most specific to least specific:

First Sub-Rules (Most Specific) - Should capture the lowest number of endpoints

Very specific criteria

Narrow scope

Handles edge cases and special conditions

Middle Sub-Rules - Broader criteria

More endpoints matched

General conditions

Last Sub-Rule (Most General) - Catch-all sub-rule

Lowest specificity

Highest number of endpoints

Handles remaining unmatched endpoints

Why Specific Rules First:

According to the documentation:​

"When an endpoint is found to match a sub-rule, no subsequent rules are evaluated for the endpoint."

This "first match wins" behavior requires:

Most specific rules first - Ensure special cases are handled correctly

General rules last - Catch remaining endpoints that don't match specific criteria

Avoid premature matches - If a general rule appears first, specific rules never execute

Example Sub-Rule Ordering:

According to the RADIUS documentation:​

text

Sub-Rule 1 (Most Specific, Lowest Count):

Condition: Windows 7 AND Antivirus NOT Running AND Not Encrypted

Lowest number of endpoints - specific conditions

Sub-Rule 2 (More General, Moderate Count):

Condition: Windows Endpoint AND Missing Patches

More endpoints - broader criteria

Sub-Rule 3 (Least Specific, Highest Count - Catch-All):

Condition: Windows Endpoint (Any)

Highest number - captures all remaining Windows endpoints

Why Other Options Are Incorrect:

A. Last rule should capture the highest number - While the last rule may capture many endpoints, the key best practice is about the FIRST rule capturing the LOWEST

C. Second rule should capture the highest number - Sub-rule order is specific to general, not based on position 2

D. Last rule should not use a catch-all - Best practice is that the LAST rule should be the catch-all

E. First rule should capture the highest number - This is the OPPOSITE of correct practice

Referenced Documentation:

Forescout RADIUS Plugin Configuration Guide v4.3 - Sub-Rules section​

Defining Forescout Platform Policy Sub-Rules​

Sub-Rule Advanced Options​