With IPHost Network Monitor you can run simple snmp requests against a Fortinet device in your network.
fgVdTable
fg Vd Table
1.3.6.1.4.1.12356.101.3.2.1
A table of virtual domains configured on the device
Back to FORTINET-FORTIGATE-MIB MIB page.
IPHost Network monitor allows you to monitor fgVdTable on Fortinet device via the SNMP protocol. Download IPHost Network Monitor (500 monitors for 30 days, 50 monitors free forever) to start monitoring Fortinet switches right now.