What is the Vista setting to allow assigning all zeros to the host portion of the IP address?I want to assign my PC an IP address of 66.93.140.248, with a subnet mask of 255.255.255.248. I realize this is an IP address of all zeros in the host portion of the IP address, but this should be allowed. I know with cisco, you can use the option "subnet zero" and this will allow you to assign this IP address/subnet mask combination.Thanks Eric V.

Hi Eric, Thank you for your post. Please understand that Network Address is not the same as Subnet Zero Network Address is the first IP address in the range of IP addresses. To be more precise, the Network Address is the address in which all binary bits in the host portion of the IP address are set to zero. Network Address is used to specify a network, so it cannot be assigned to any individual host. I believe it is also true in Cisco. Subnet Zero is the first subnet obtained after subnetting a network address. The IP addresses (expect the Network Address and Broadcast Address) within this subnet can be assigned to a host. For example, if network 172.16.0.0/16 is subnetted by borrowing three bits from the host portion, eight (23) subnets are obtained. The table below is an example showing the subnets obtained by subnetting the address 172.16.0.0, the resulting subnet mask, the corresponding broadcast addresses, and the range of valid host addresses. Subnet Address Subnet Mask Broadcast Address Valid Host Range 172.16.0.0 255.255.224.0 172.16.31.255 172.16.0.1 to 172.16.31.254 172.16.32.0 255.255.224.0 172.16.63.255 172.16.32.1 to 172.16.63.254 172.16.64.0 255.255.224.0 172.16.95.255 172.16.64.1 to 172.16.95.254 172.16.96.0 255.255.224.0 172.16.127.255 172.16.96.1 to 172.16.127.254 172.16.128.0 255.255.224.0 172.16.159.255 172.16.128.1 to 172.16.159.254 172.16.160.0 255.255.224.0 172.16.191.255 172.16.160.1 to 172.16.191.254 172.16.192.0 255.255.224.0 172.16.223.255 172.16.192.1 to 172.16.223.254 172.16.224.0 255.255.224.0 172.16.255.255 172.16.224.1 to 172.16.255.254 In the example above, the first subnet (subnet 172.16.0.0/19) is called subnet zero. (Quote: http://www.cisco.com/warp/public/105/40.html) The IP addresses: 172.16.0.0/19, 172.16.32.0/19, 172.16.64.0/19, 172.16.96.0/19, 172.16.128.0/19, 172.16.160.0/19, 172.16.192.0/19 and 172.16.224.0/19 are Network Addresses, and they cannot be assigned to any individual host. I Hope the above information is helpful. Sincerely, Joson Zhou Microsoft Online Community Support