Netbackup server & Exchange server are on the different Domain.

hello

    We have requirement to backup the 2 exchange servers that are on the different domain.

For example

      - domain1.com   there are  exchange, nbu server.

      - domain2.com    there is exchange server.

     I can backup the exchange server on domain1, But getting error about nbsd when backup Exchange server in domain2.com

Is it possible to backup the Exchange server that is on the different domain with NBU server.

Thank you.