User`s guide

186 Appendix E Understanding IP Addresses and Subnet Masking

4. Define Host Addresses for Subnet #14-3 (140.25.227.0/24)

Examine the host addresses that can be assigned to subnet #14-3 (140.25.227.0/24). Each

subnet of subnet #14-3 has 8 bits in the host-number field. This means that each subnet

represents a block of 254 valid host addresses (2

-2). The hosts are numbered 1 through 254.

The valid host addresses for subnet #14-3 are shown below. The italicized portion of each

address identifies the extended-network prefix, while the bold digits identify the 8- bit host-

number field:

Subnet #14-3: 10001100.00011001.11100011.00000000 = 140.25.227.0/24

Host #1 10001100.00011001.11100011.00000001 = 140.25.227.1/24

Host #2 10001100.00011001.11100011.00000010 = 140.25.227.2/24

Host #3 10001100.00011001.11100011.00000011 = 140.25.227.3/24

Host #4 10001100.00011001.11100011.00000100 = 140.25.227.4/24

Host #5 10001100.00011001.11100011.00000101 = 140.25.227.5/24

Host #253 10001100.00011001.11100011.11111101 = 140.25.227.253/24

Host #254 10001100.00011001.11100011.11111110 = 140.25.227.254/24

5. Define the Sub 2 -Subnets for Subnet #14-14 (140.25.238.0/24)

After subnet #14 is divided into 16 subnets, subnet #14-14 is further subdivided into 8 equal-

size address blocks. Since 8 = 2

, three more bits are required to identify each of the 8

subnets. This means the organization must use a /27 as the extended-network prefix length.

The eight subnets of the 140.25.238.0/24 address block are shown below. The subnets are

numbered 0 through 7. The italicized portion of each sub-subnet address identifies the

extended-network prefix, while the bold digits identify the 3-bits representing the subnet 2 -

number field:

Subnet #14-14: 10001100.00011001.11101110.00000000 = 140.25.238.0/24

Subnet#14-14-0: 10001100.00011001.11101110.000 00000 = 140.25.238.0/27 Subnet#14-

14-1: 10001100.00011001.11101110.001 00000 = 140.25.238.32/27 Subnet#14-14-2:

10001100.00011001.11101110.010 00000 = 140.25.238.64/27 Subnet#14-14-3:

10001100.00011001.11101110.011 00000 = 140.25.238.96/27 Subnet#14-14-4:

10001100.00011001.11101110.100 00000 = 140.25.238.128/27 Subnet#14-14-5:

10001100.00011001.11101110.101 00000 = 140.25.238.160/27 Subnet#14-14-6:

10001100.00011001.11101110.110 00000 = 140.25.238.192/27 Subnet#14-14-7:

10001100.00011001.11101110.111 00000 = 140.25.238.224/27