pfSense

We currently set "reservations-in-subnet": true for all subnets but we do not explicitly set reservations-out-of-pool. reservations-out-of-pool defaults to false which makes Kea respect static mappings as reservations inside defined pools, which was not viable in ISC DHCP.

Setting reservations-out-of-pool and reservations-in-subnet both to true makes Kea assume all reservations are outside of pools, which our input validation already enforces, and increases performance since Kea doesn't need to check pools for reservations.

So right now we could be benefiting from the extra performance but we do not (because the right options are not set in Kea), and/or we could be benefiting from allowing users to make reservations in pools, but we do not (because the input validation prevents it).

So we have a few choices to fix this inconsistency:

1. Set reservations-out-of-pool to false unilaterally for the performance gain alone.
2. Relax the input validation on static mappings to allow reservations inside pools, which users frequently request.
3. Make a new option on the Kea Settings tab to control this, with the backend option and input validation changing based on what the user selects.

Option 3 is the most flexible and would make users happy both ways, and we could default to the current behavior and have users opt-in only if they want the new behavior even if there is a performance hit.