Dr_agent - source and destination

Is this true? Do I need a dr_agent on both source and destination?

I have tried both and they both work. On dr_agent on destination only and on both sides. I think it does not matter as long as there are multiple agents running. Also, leaving some agents on the source once the destination one is aboard could cause some wasted space on the source.

Is “disaster recovery” to be understood as “push” or “pull”?
The documents are very unclear about DR.