Question

Consider a subnet with prefix 192.168.32.128/25.

a. (7 pts) Give the range of IP addresses (of form xxx.xxx.xxx.xxx – xxx.xxx.xxx.xxx) that can be assigned to this network.

b. (7 pts) Suppose an ISP wants to create two subnets from this block, with each block having the same number of IP addresses. What are the prefixes (of form a.b.c.d/x) for the two subnets?

Answer 1

Answer: For the subnet with prefix 128.119.40.128/26 we can see that 26 bits are used to identify as the network address and remaining 6 bits out of the 32 bit IPV4 address is used to represent the hosts. So there can be a maximum of 64 hosts. So any IP address from 128.119.40.128/26 to 128.119.40.191/26 is an example. For the second of the question where ISP owns addresses of the form 128.119.40.64/26, 26 bits are used for the network identification and there can be 64 hosts. If e want to create four subnets with each having equal number of IP addresses, we can assign 16 hosts to each subnet and use 28 bits for network identification or subnet mask. The subnets will be below. 128.119.40.64/28 128.119.40.80/28 128.119.40.96/28 128.119.40.112/28