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

According to theForescout Resiliency Solutions User Guideand theForescout Platform Installation Guide,High Availability (HA) requires a license. The documentation explicitly states:

'If your deployment is using Centralized Licensing Mode, you must acquire a valid ForeScout CounterACT Resiliency license. The Resiliency license supports: High Availability Pairing for Enterprise Manager is supported by the Forescout CounterACT See License.'

High Availability Licensing Requirements:

According to the official documentation:

Per-Appliance Licensing Mode:

'The demo license for your High Availability system is valid for 30 days. You must install a permanent license before this period expires.'

Centralized Licensing Mode:

'If your deployment is using Centralized Licensing Mode, you must acquire a valid ForeScout CounterACT Resiliency license for Appliances, or a CounterACT See License for Enterprise Manager High Availability Pairing.'

License Usage Considerations:

According to the documentation:

'You should use the IP address of the High Availability pair when requesting a High Availability license'

'If a license is only issued to the Active node in a High Availability pair, the system may not operate after failover to the Standby node'

'Both nodes must be up when requesting a license'

Why Other Options Are Incorrect:

A . If HA reboots, this is an indication of a problem- According to the documentation, reboots can occur during the setup process: 'Following the second reboot in the high availability setup, allow time for data synchronization' - this is normal, not an indication of a problem

B . Set up HA on the Secondary node first- Incorrect order. According to the documentation, 'Before you begin setting up the Secondary node Forescout Platform device, verify that the Primary node Forescout Platform device is powered on' - the Primary node must be set up first

C . Connect devices to the network and to each other- While devices must be connected, this is a general infrastructure requirement, not specific to HA setup. The more specific requirement is licensing

D . HA needs to be manually configured on the secondary appliance in order to sync correctly- According to the documentation, the Secondary node configuration uses a setup process that is distinct from the Primary node: 'When setting up the Secondary node device, use the same sync interfaces and netmask settings used in the Primary node device' - this is guided setup, not manual configuration for sync

High Availability Setup Process:

According to the documentation:

Set up Primary Node- 'Select High Availability mode: 1) Standard Installation 2)High Availability -- Primary Node'

Set up Secondary Node- 'Set up a device as the secondary node' (secondary node connects to primary automatically)

Licensing- 'You must install a permanent license before this period expires'

Referenced Documentation:

Forescout Resiliency Solutions User Guide (v8.0)

Forescout Installation Guide v8.1.x

Forescout Resiliency and Recovery Solutions User Guide v8.1

Set up and configure a device as the primary node

Set up a device as the secondary node