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:
- In UMP click 'Actions' and select 'Discovery Wizard'. Select the hub (it must have the discovery_agent probe installed for this process to work), click 'Launch Wizard', click 'Scopes' at the top right of the Discovery Wizard window and click 'New Scope'.
- Now give the scope a name and add the IP address of all the affected servers. Go to the 'Schedule' tab and select an option to run the discovery. If you are able to run the discovery immediately just select 'Run discovery now' and click 'Finish'. If not you can schedule it to the most convenient time.