DHCP only for hosts that are in build mode

Problem:

Is it possible to prevent the foreman proxy to create dhcp leases for hosts that are not in build mode?

I have had some issues with servers that where not able to continue booting after going back from pxeboot to localboot. Therefor i would like to skip the pxeboot.

Expected outcome:

Only servers that are in build mode will get a dhcp lease, other servers will timeout and boot through.

Foreman and Proxy versions:

Foreman Version 1.17
Proxy Version 1.17

Thanks for your help!