Question

In this chapter, you subnetted a Class C private network into six subnets. In this project, you work with a Class B private network. Complete the steps as follows: 1. Your employer is opening a new location, and the IT director has assigned you the task of calculating the subnet numbers for the new LAN. You’ve determined that you need 50 subnets for the Class B network beginning with the network ID 172.20.0.0. How many host bits will you need to use for network information in the new subnets? 2. After the subnetting is complete, how many unused subnets will be waiting on hold for future expansion, and how many possible hosts can each subnet contain?

Answer 1

Answer:

1. 10 bits

2. 1022 Hosts / Subnet

Explanation:

Given Network ID is 172.20.0.0

Class B network contains :

Network ID = 16 bits

Host ID = 16 bits

For subnetting always host id bits are used.

Number of subnets required = 50. Subnets are always in power of two. Nearest power of two to 50 is 26 = 64.

So, to create subnet we require 6 bits from host id and 64 subnets can be created with those 6 bits.

1)

Number of host bits needed for new subnets for network information = 6 bits.

Therefore, New network information contains :

Network ID of subnet = 16 + 6 = 22 bits

Host ID = 16- 6 = 10 bits.

2)

Subnets required = 50

Subnets created with 6 bits = 64.

Number of subnets unused for future expansion = 64 - 50 = 14 subnets.

Host ID part contains 10 bits. Therefore, Total number of Hosts /Subnet = 210 = 1024 Hosts.

Number of usable hosts per subnet = 1024 -2 = 1022 Hosts / Subnet.