A director is an instance to distribute traffic to attached scanning nodes. A scanning node is an instance which scans the traffic.
These modes are available in Proxy HA, Bridge and Router Mode.
Each director is a scanning node at the same point of time btw.
For a singlel node you don't need to configure anything it is just doing it's job.
But any other mode where you want to have failover, you are required to configure directors and scanning nodes, or better said need to differentiate between them,
thanks for the info. that means if i configure 2 units as HA. 1 configure as the director node and the other scanning node. the director node will be the management server to configure all the rules for the both units. am i right? sorry, i'm a little confuse about the version 7.
Your statement is correct. As Michael said, if you have multiple, you would need to differentiate between their roles, keeping in mind the director can act as both.