A subnet listed in the Subnets tab of the Network Discovery dialog box might not be searched during a Network Discovery, even if the subnet is valid. To be searched, a subnet must be in scope. To ensure that a subnet is in scope, you must specify all subnets leading to it from the server running Network Discovery, or the subnet must be within the number of router hops specified in the SNMP tab. Consider the following network:
In a Network Discovery run from Server 1, subnets D and E will be searched only if Subnets A and C are specified in the discovery. If you specify Subnet A, Router 2 is reached, and Router 2 knows about subnet C. If you specify subnet C, Router 3 is reached, and Router 3 knows about Subnets D and E.
Subnets D and E can also be reached from Server 1 if at least two router hops are specified in the SNMP tab.
Resources on an out-of-scope subnet can be found, but only in these two cases:
Configure Network Discovery
Network Discovery Properties Dialog Box: Subnets Tab
Network Discovery Overview