Assume that you have been given the IP address 192.168.64.0/22 (255.255.252.0) for use in your corporate network. This address currently has 210=1024 host addresses (/22 indicates that 22 of 32 bits are used for the network portion of the address, leaving 10 for the host portion). In order to more efficiently utilize the addresses, you will need to divide them into custom blocks based on the needs of each department. The Sales department is the largest with 225 host devices. You will need to subnet the /22 network into subnets that will support at least 225 hosts.
Using the 2n-2>=225 formula where n is the number of host bits you need to have in order to create at least 225 usable IP addresses, you determine that n=8 bits need to be available for hosts. The other 2 bits will be borrowed (converted to subnet identifiers), making your custom subnet mask 255.255.255 or /24.
Perform the subnetting operation and complete the table below:
Reference Subnet ID Network Addr. First Usable Last Usable Broadcast Addr.
First 0 192.168.64.64/24 192.168.64.127
Second 1 192.168.64.128/24 192.168.64.191
Third 2 192.168.64.192/24 192.168.64.255
Fourth 3 192.168.64.256/24 192.168.64.319