About trusted primary servers
A trust relationship between NetBackup domains lets you do the following:
Select specific domains as a target for replication. This type of Auto Image Replication is known as targeted A.I.R.
Without a trust relationship, NetBackup replicates to all defined target storage servers. A trust relationship is optional for Media Server Deduplication Pool and PureDisk Deduplication Pool as a target storage. To use a Cloud Catalyst storage server, a trust relationship is required.
Include usage reporting for multiple primary servers.
Primary servers can use a NetBackup certificate authority (CA) certificate or an external CA certificate. NetBackup determines the CAs used by the source and the target domains and selects the appropriate CA to use for communication between the servers. If the target primary server is configured for both CA types, NetBackup prompts you to select the CA that you want to use.