I noticed some alarms in SOI have 'Unknown' in the 'Name' column. After reviewing the article TEC1344659 it seems the root cause is the corresponding devices in UIM have a NULL value in the dns_name column of CM_COMPUTER_SYSTEM table.
Since UIM 8.31 the dns_name field can get populated less frequently than before. Please see the article TEC000005241 for details of the new update process.
The dns_name field in CM_COMPUTER_SYSTEM table will get populated by the discovery_agent probe when the device is discovered.
In order for this process to work the server where discovery_agent is running must be able to do a reverse lookup on the target device's IP address.
If the reverse lookup works fine then running the Discovery Wizard against the problem devices should resolve the problem: