Why not all of my network devices are discovered?

Here is the list of the the possible reasons why some of the network devices can be missing after Network Discovery:

1. SNMP is not configured or misconfigured  on missing device (Test SNMP operation via Tools -> SNMP Walk).
2. SNMP ACL on missing device does not permit requests from Nectus IP Address  (Test SNMP operation via Tools -> SNMP Walk).
3. IP address of the missing network device is outside of the range of configured subnets in Network Discovery and CDP is disabled on missing device.
4. IP address of the missing network device is outside of the range of configured subnets in Network Discovery and device is located inside isolated CDP domain.
5. There a Firewall between missing device and Nectus and it block ICMP and /or SNMP traffic.