Not every Backup Exec Agent can talk to every server. Here's the combinations that will work.
| Agent V9.x | Agent V10.0 | Agent V10d | Agent V11d | Agent V12d | |
| Server V9.x | Yes | No | No | No | No |
| Server V10.0 | Yes | Yes | Yes | No | No |
| Server V10.1 | Yes | Yes | Yes | No | No |
| Server V11d | No | No | No | Yes | Yes? |
| Server V12d | No | No | No | Yes? | Yes |
(Entries with a "?" need to be verified)
For example, if you have a V9 server and V9 agents, you can upgrade the server to V10.0 and get backups without upgrading all of the agents. If you then upgrade the server from V10.0 to V11d, you won't be able to run backups until all of the agents are upgraded to the V11d agent.