The NOT checkbox negates the criteria inside the property. According to the Forescout Administration Guide, when the NOT checkbox is selected on a policy condition criteria, it reverses the logic of that specific criterion evaluation.​

Understanding the NOT Operator in Policy Conditions:

In Forescout policy configuration, the NOT operator is a Boolean logic operator that inverts the result of the property evaluation. When you select the NOT checkbox:

Logical Inversion - The condition is evaluated normally, and then the result is inverted

Criteria Negation - If a criteria would normally match an endpoint, selecting NOT causes it NOT to match

Property-Level Operation - The NOT operator applies specifically to that individual property/criterion, not to the entire rule​

Example of NOT Logic:

Without NOT:

Condition: "Windows Antivirus Running = True"

Result: Matches endpoints that HAVE antivirus running

With NOT:

Condition: "NOT (Windows Antivirus Running = True)"

Result: Matches endpoints that DO NOT have antivirus running

NOT vs. "Evaluate Irresolvable As":

According to the documentation, the NOT operator and "Evaluate Irresolvable As" are independent settings:​

NOT operator - Negates/inverts the criteria evaluation itself

"Evaluate Irresolvable As" - Defines what happens when a property CANNOT be resolved (is irresolvable)

These serve different purposes:

NOT determines what value to match

Evaluate Irresolvable As determines how to handle unresolvable properties

Handling Irresolvable Criteria:

According to the administration guide documentation:​

"If you do not select the Evaluate irresolvable criteria as option, the criteria is handled as irresolvable and the endpoint does not undergo further analysis."

The "Evaluate Irresolvable As" checkbox allows you to define whether an irresolvable property should be treated as True or False when the property value cannot be determined. This is independent of the NOT checkbox.​

Why Other Options Are Incorrect:

A. The NOT checkbox means the "Evaluate Irresolvable as" should be set to True - Incorrect; NOT and Evaluate Irresolvable As are independent settings

B. The external NOT does not change the meaning of "evaluate irresolvable as" - While technically true that NOT doesn't change the Evaluate Irresolvable setting, the answer doesn't explain what NOT actually does

C. Has no effect on irresolvable hosts - Incorrect; NOT negates the criterion logic regardless of whether it's resolvable

E. The NOT checkbox means the "Evaluate Irresolvable as" should be set to False - Incorrect; NOT and Evaluate Irresolvable As are independent

Policy Condition Structure:

According to the documentation, a policy condition consists of:​

Property criteria combined with Boolean logic operators

Individual criterion settings including NOT operator

Irresolvable handling options that are separate from the NOT operator

Referenced Documentation:

Forescout Administration Guide - Define policy scope​

Forescout eyeSight policy sub-rule advanced options​

Handling Irresolvable Criteria section​

Working with Policy Conditions