In Palo Alto Networks firewalls, each virtual system (VSYS) is typically isolated from other VSYSs, meaning that traffic between different VSYSs cannot pass through the firewall by default. In this case, since the interfaces for each VSYS are assigned to separate virtual routers (VRs), and the desired traffic is still not passing between the two VSYSs, the firewall needs to be explicitly configured to allow traffic between them.
The required configuration is to add each VSYS to the list of visible virtual systems of the other VSYS. This allows inter-VSYS communication to be enabled, effectively permitting the traffic to pass between the zones of different VSYSs.

OCSP verification is enabled within a certificate profile, which defines the trusted certificate authorities and the validation methods used for certificate-based authentication, including real- time revocation checking through OCSP responders.

Basic Concept: CIE segments provide filtered identity datasets and redistribute them only to selected firewall populations.
Why B is Correct: Segments are designed for this partitioning requirement: internal firewalls receive employee identities and DMZ firewalls receive partner identities.
Why A is Wrong: Panorama templates, which can be used to push different User-ID agent configurations to each firewall group is a cloud deployment or routing approach, but it does not match the required managed insertion model, resilience pattern, or Panorama-controlled policy design in this scenario.
Why C is Wrong: Multiple tenants, where a separate CIE tenant is required for each user directory to maintain isolation is a cloud deployment or routing approach, but it does not match the required managed insertion model, resilience pattern, or Panorama-controlled policy design in this scenario.
Why D is Wrong: Directory sync filtering, which is used at the source to prevent specific OUs from being imported into CIE is a cloud deployment or routing approach, but it does not match the required managed insertion model, resilience pattern, or Panorama-controlled policy design in this scenario.

This approach best addresses the enterprise's requirements for certificate-based authentication, OCSP checks, and consistent policy enforcement:
Distributing the root and intermediate CA certificates via Panorama ensures that all firewalls in the enterprise are consistent in their trust chain and can validate certificates properly.
Configuring OCSP responder profiles on each firewall offloads the revocation checks to an internal OCSP server, which reduces the overhead on the firewalls and ensures fast, real-time certificate status checks.
Using CRL checks as a fallback ensures reliability in case the OCSP responder is unavailable.
Separate certificate profiles for users and devices ensure that the firewall can enforce different security policies based on the type of certificate (user vs. device).
Automated certificate enrollment methods such as Group Policy or SCEP streamline certificate distribution to endpoints, ensuring efficient management of certificates across geographically dispersed firewalls.

Basic Concept: GlobalProtect pre-logon uses machine identity before user login, while user logon can use SAML/MFA against a cloud IdP.
Why D is Correct: Certificate-based authentication for pre-logon plus SAML for user logon satisfies both endpoint management before login and MFA-protected user authentication.
Why A is Wrong: Cookies can reduce repeated prompts after authentication, but cookie-based authentication does not prove machine identity before user logon or provide cloud IdP MFA for user logon.
Why B is Wrong: SAML is user-centric and requires an interactive identity flow, so it is not appropriate for machine pre-logon before a user session exists.
Why C is Wrong: Kerberos can provide AD-based SSO, but a single Kerberos profile does not meet cloud IdP MFA and machine-certificate pre-logon requirements.