sudo VBoxManage dhcpserver modify --netname intnet --ip 10.13.13.100 --netmask 255.255.255.0 --lowerip 10.13.13.101 --upperip 10.13.13.254 --enable

I have use this command in my terminal Host OS in order to assifned IP for my internal network , as i am runing two Guest OS Ubuntu and FedoraF17 but i am unable to see any IP range in between, :( nor connection is established. Please help