In this section of the Server set properties dialog, you can specify how often servers are polled:
Polling interval when all server polls are successful
How often this Server set is polled.
You should balance this between how quickly you want problems detected, and how much traffic you want Simple Failover to cause.
Note: Polling too often may be flagged as a DOS attack by some firewalls.
Polling interval when one or more server pools have failed
After a problem first is detected, subsequent polls will use this interval.
Retry failed polls __ times - at an interval of
Retry failed polls this number of times / at this interval before considering the server failed.
Poll servers sequentially and stop at first successfully polled server
Enable this if you don't want to poll backup/standby servers as long as your primary servers are responding correctly.