Não é possível controlar os endereços dinâmicos de pedidos alocados com o ISC dhcpd versão 3 ou posterior. Na página de manual do dhcpd.conf :
The DHCP server generates the list of available IP addresses from a hash table. This means that the addresses are not sorted in any particular order, and so it is not possible to predict the order in which the DHCP server will allocate IP addresses. Users of previous versions of the ISC DHCP server may have become accustomed to the DHCP server allocating IP addresses in ascending order, but this is no longer possible, and there is no way to configure this behavior with version 3 of the ISC DHCP server.