Ryuujin
As far as I am aware, the IP address of an asset is neither available for import/export in the current version. It's possible that IP address was exported in a previous version but it was removed since we added the ability to have multiple interfaces and still needs to be added back.
The currently available columns are: 'Name', 'Description', 'Type', 'Make', 'Model', 'Serial Number', 'Operating System', 'Purchase Date', 'Warranty Expire', 'Install Date', 'Assigned To', 'Location', 'Notes'