Network discovery doesn't detect and scan network devices like switches via SNMP. Since the upgrade to 8.1 RU2 and RU3, the network scan detects devices for IPs that do not exist.
If a non-existing IP is scanned, it detects the device as unknown.

Steps to reproduce:

1. Take any IP Address say 0.0.0.0
2. Add this to discovery task and execute.
3. On completion, it shows:

Status: Completed

O/P Properties:
Discovery statistics:
Total devices processed: 1
New devices added: 1
Devices updated: 0
Device add failures: 0
Device update failures: 0

Symantec Management Platform (SMP) 8.1 Release Update (RU) 2, 3 and 4.

This issue has been fixed in 8.1 RU5 and will also be fixed in 8.5.  After upgrading you may still need to run through steps 1-3 below to clean up previous invalid data.

A point-fix is available for this issue in 8.1 RU2, RU3 and RU4 (attached).  To install the point-fix please follow the steps below:

1. First, delete the invalid devices by browsing to Manage > All Resources > Default > All Resources > Asset > and select Network Resources.
2. Most of the devices that have no name or an IP address as a name are invalid devices. Sort by name to get the list.  You can also limit what is shown by typing in the first part of the IP addresses in the Search field to make it easier.
3. Delete the devices by using multi-select, right-click, and select Delete. 
   
4. Next, apply the point-fix to resolve the issue going forward.
5. Log in to the Symantec Management Platform (SMP) server with the application identity.
6. Download the attached archive and extract to a folder on the SMP server in a location not in the Altiris install directory.
7. Execute the PFInstaller2.exe.
8. Choose to install files.
9. NOTE: Services will restart during this process.