Standby pool Member

Priority-based load balancing with or without dynamic persistence doesn't quite address this requirement. Priority load balancing allows you to set a preferred server to which traffic should return once it recovers. With just Priority, and with dynamic persistence of any kind enabled, when a higher priority nodes come back up after failing, you will see traffic distributed across multiple pool members until old connections/sessions die off. With just Priority and no persistence, existing sessions will break once the preferred node again becomes available.

For true single node peristence, see here:

https://devcentral.f5.com/codeshare/single-node-persistence