Can we install backup exec on a dain controller
You can install on a DC provided it is not Read Only... Note that it is recomended that B.E. "Media server" stand alone as its own machine. Additionally B.E. will sometimes require a reboot of the server when patched up.. this may cause issue if Shared as a DC
I hope this posting was helpful
What type of server is this? Take a look at the SCL to make sure it is supported: Backup Exec 12.0 Sofware (SCL)
There is no harm in installing BE on a DC. But as a backup admin I would prefer installing BE on a dedicated non DC machine.
If you can, install it on another server, but if you have no choice, it can be installed on a DC but realize that your DC's resources, such as RAM and CPU cycles will be stretched to the max, so don't do backups or restores during production hours.