auth.conf is only set the restiction on Java console... and its very limitted..
auth.conf does not have any control if you perform any activty though admin console or from Command like.
NBAC is fully populated authentacation server which can manage all the way of Netbackup access methods(GUI, CLI). with detail loggin and more granunal level of access management
more information can be found in below tech note and and netbackup securuty guide
http://www.symantec.com/business/support/index?page=content&id=HOWTO46963
http://www.symantec.com/business/support/index?page=content&id=HOWTO46729
