An engineer must configure guest access on Cisco ISE for company visitors. Which step must be taken on the Cisco ISE PSNs before a guest portal is configured?

Installing SSL certificates on the Policy Service Nodes (PSNs) is a fundamental prerequisite for configuring guest portals. This step ensures that guest users interact with a trusted and secure web interface, preventing browser security warnings and enabling encrypted communication during the guest onboarding process.

Creating a node group is for grouping PSNs for administrative purposes or high availability, not a prerequisite for guest portal functionality itself.

Enabling profiling services is for device identification, which can be part of a guest flow but is not strictly required before the portal configuration.

Enabling session services is part of the PSN's core functionality for handling active sessions, but it's not a distinct step required *before* configuring the guest portal itself.