I added 192.168.120.0/24 entire network IP address to scan switches that have an SNMP credential like below image:

In this range just exist switch, but we don't have 255 switches and just 10 switches. I considered show me just 10 switches that scanned in switches section of Assets tab. It's right, but in workstation section of Assets tab shows me other IP address that null and doesn't exist. like below image:

These IP addresses are null and don't exist and also isn't pingable. What should I do?

Thanks