Question

Suppose your company has leased one Class C license, 120.10.10.0, and wants to sublease the first half of these IP addresses to another company. What is the CIDR notation for the subnet to be subleased? What is the subnet mask for this network?

Answer 1

The CIDR notation for the first half of the subleased Class C network 120.10.10.0 is 120.10.10.0/25 with a subnet mask of 255.255.255.128.

Step-by-step explanation:

The company has a Class C IP address of 120.10.10.0. When splitting this Class C network into two subnets, each subnet will have half of the hosts of the original Class C network. The CIDR notation for the first subnet, which is the first half of the Class C address, will use one additional bit for the network portion from the original. Since a Class C address has a default subnet mask of 255.255.255.0, which is equivalent to CIDR notation /24, adding one bit for subnetting changes the mask to 255.255.255.128 or /25.

Therefore, the CIDR notation for the subnet to be subleased would be 120.10.10.0/25, which correlates with a subnet mask of 255.255.255.128.