An engineer must enable the highest level of logging when troubleshooting Cisco NFVIS.

Comprehensive and Detailed Explanation

Cisco NFVIS logging levels (from lowest to highest):

critical

error

warning

info

debug←highest verbosity

To capture maximum diagnostic detail, engineers must enabledebuglogging on theoperational log type, which records system activity and runtime behavior.

Thus the correct command is:

system set-log logtype operational level debug

This provides the deepest troubleshooting visibility.