Deny dhcp service to mac address

[Guest]

[gabriele.lamon]

I need to deny the ip lease to some mac address and it would be useful to have the possibility to do it from the dhcp configuration like fixed lease.
I've tried to give them fixed lease with ip like 127.0.0.1, .2, .3, etc. but it doesn't work, they get a valid ip instead the one i try to gave them.

Lelle.