Can the OS of the NetBackup master server be other than RHEL?

Master server can be installed and supported at

• A supported windows server
• Oracle linux
• redhat linux
• suse linux
• centos linux

You may be able to install and run without any problems netbackup master on other platforms (I have never tried) but you are your own.

https://www.veritas.com/bin/support/docRepoServlet?bookId=NB_10_OSSCL&requestType=pdf

Pls don't use CentOS - CentOS 7 is end of life : End dates are coming for CentOS Stream 8 and CentOS Linux 7 – Blog.CentOS.org