The table below defines the discovery stages.
 
In this stage… The Discovery Engine does this…
Excluding addresses Processes addresses that have been specifically excluded from discovery. For example, you may want to exclude devices if you have encountered a device with an unusual problem that is interfering with discovery.This option is available in the Advanced Discovery wizard.
 
Rediscovering devices Rediscovers the devices stored in the current database and then updates the database with the current device configurations. 
 
Searching for routers Reads the route tables of the default gateway. This provides information about the other routers existing on the network.
 
Querying ARP caches Queries the ARP cache entries from the routers discovered in the previous stage. The ARP caches contain addresses of network devices recently active on the network.
 
Including addresses Discovers addresses that have been specifically included for discovery. For example, you may want to include devices if you have added a new device to the network. Then you can run discovery to add it to your database without waiting for a long discovery cycle to complete.This option is available in the Advanced Discovery wizard.
 
Pinging network PINGs each address on the subnets that have been discovered.