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

According to the Forescout Platform Administration Guide and Certificate Configuration documentation, Forescout uses the Online Certificate Status Protocol (OCSP) to verify the revocation status of certificates.​

OCSP in Forescout:

According to the official Forescout documentation:​

"You can also configure the use of Online Certificate Status Protocol (OCSP) and set up validation method failover between CRL and OCSP."

And further:​

"The Forescout Platform supports certificate revocation lists (CRL) and Online Certificate Status Protocol (OCSP) for smart card authentication."

What OCSP Does:

According to the Wikipedia and Fortinet OCSP documentation:​

"The Online Certificate Status Protocol (OCSP) is an Internet protocol used for obtaining the revocation status of an X.509 digital certificate."

OCSP provides:

Real-Time Status Verification - Checks current certificate revocation status

Request/Response Protocol - Sends a query to an OCSP responder

Revocation Status Response - Returns "good," "revoked," or "unknown"

Efficient Alternative to CRL - Smaller data payload than downloading full certificate revocation lists

How OCSP Works:

According to the OCSP documentation:​

Request Sent - Client sends OCSP request to OCSP responder (server operated by CA)

Status Verification - Responder checks revocation status with trusted CA

Response Returned - Responder returns current status, revoked, or unknown

Decision Made - Application (like Forescout) accepts or rejects the certificate based on response

Forescout Smart Card Certificate Validation:

According to the Forescout documentation:​

When using smart card authentication, Forescout:

Supports OCSP - Sends OCSP requests for certificate revocation status

Supports CRL - Also supports Certificate Revocation Lists as fallback

Failover Configuration - Can be configured to use OCSP with CRL fallback

OCSP vs. Certificate Revocation List (CRL):

According to the documentation:​

Aspect

OCSP

CRL

Data Size

Smaller response

Larger list

Update Frequency

Real-time status

Periodic updates

Network Load

Lower burden

Higher burden

Timeliness

Current status

Potentially outdated

Processing

Less complex

More complex parsing

Forescout uses OCSP because it provides real-time, efficient certificate status verification.

Why Other Options Are Incorrect:

A. PKI Certificate Revocation Protocol (PCRP) - This is not a standard protocol; PCRP does not exist

C. Online Revocation Status Protocol (ORSP) - This is not the correct name; the protocol is OCSP, not ORSP

D. Certificate Revocation List Protocol (CRLP) - While Forescout supports CRL, the primary protocol for real-time status is OCSP

E. Certificate Revocation Protocol (CRP) - This is not a standard protocol; the correct protocol is OCSP

Referenced Documentation:

Smart Card Certificate Configuration for Forescout Platform​

Using Forescout Platform Smart Card Authentication​

Client-Server Connection documentation​

Audit Actions - OCSP for Syslog validation​

Online Certificate Status Protocol (OCSP) - Wikipedia​

What Is Online Certificate Status Protocol (OCSP) - Fortinet