Chapter 9 High Availability : HA and failover protection : Remote link failover : Monitoring multiple IP addresses from one interface
  
Monitoring multiple IP addresses from one interface
You can add multiple IP addresses to a single link monitor to use HA remote IP monitoring to monitor more than one IP address from a single interface. If you add multiple IP addresses, the health checking will be with all of the addresses at the same time. The link monitor only fails when no responses are received from any of the addresses.
config system link-monitor
edit port2
set server 192.168.20.20 192.168.20.30 172.20.12.10
end