11.6.6 Lab – Calculate IPv4 Subnets Answers

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11.6.6 Lab – Calculate IPv4 Subnets Answers

Lab – Calculate IPv4 Subnets (Answers Version)

Answers Note: Red font color or gray highlights indicate text that appears in the Answers copy only.

Objectives

Part 1: Determine IPv4 Address Subnetting

Part 2: Calculate IPv4 Address Subnetting

Background / Scenario

The ability to work with IPv4 subnets and determine network and host information based on a given IP address and subnet mask is critical to understanding how IPv4 networks operate. The first part is designed to reinforce how to compute network IP address information from a given IP address and subnet mask. When given an IP address and subnet mask, you will be able to determine other information about the subnet.

Answers Note: This activity can be done in class or assigned as homework. If the assignment is done in class, you may wish to have students work alone or in teams of 2 students each. It is suggested that the first problem is done together in class to give students guidance as to how to proceed for the rest of the assignment.

The public IP addresses used in this lab are owned by Cisco.

Required Resources

  • 1 PC (Windows with Internet access)
  • Optional: IPv4 address calculator

Instructions

Fill out the tables below with appropriate answers given the IPv4 address, original subnet mask, and new subnet mask.

Problem 1:   

Given:

Host IP Address:

192.168.200.139

Original Subnet Mask

255.255.255.0

New Subnet Mask:

255.255.255.224

 

Find:

Number of Subnet Bits

3

Number of Subnets Created

8

Number of Host Bits per Subnet

5

Number of Hosts per Subnet

30

Network Address of this Subnet

192.168.200.128

IPv4 Address of First Host on this Subnet

192.168.200.129

IPv4 Address of Last Host on this Subnet

192.168.200.158

IPv4 Broadcast Address on this Subnet

192.168.200.159

Problem 2:   

Given:

Host IP Address:

10.101.99.228

Original Subnet Mask

255.0.0.0

New Subnet Mask:

255.255.128.0

 

Find:

Number of Subnet Bits

9

Number of Subnets Created

512

Number of Host Bits per Subnet

15

Number of Hosts per Subnet

32,766

Network Address of this Subnet

10.101.0.0

IPv4 Address of First Host on this Subnet

10.101.0.1

IPv4 Address of Last Host on this Subnet

10.101.127.254

IPv4 Broadcast Address on this Subnet

10.101.127.255

Problem 3:   

Given:

Host IP Address:

172.22.32.12

Original Subnet Mask

255.255.0.0

New Subnet Mask:

255.255.224.0

 

Find:

Number of Subnet Bits

3

Number of Subnets Created

8

Number of Host Bits per Subnet

13

Number of Hosts per Subnet

8,190

Network Address of this Subnet

172.22.32.0

IPv4 Address of First Host on this Subnet

172.22.32.1

IPv4 Address of Last Host on this Subnet

172.22.63.254

IPv4 Broadcast Address on this Subnet

172.22.63.255

Problem 4:   

Given:

Host IP Address:

192.168.1.245

Original Subnet Mask

255.255.255.0

New Subnet Mask:

255.255.255.252

 

Find:

Number of Subnet Bits

6

Number of Subnets Created

64

Number of Host Bits per Subnet

2

Number of Hosts per Subnet

2

Network Address of this Subnet

192.168.1.244

IPv4 Address of First Host on this Subnet

192.168.1.245

IPv4 Address of Last Host on this Subnet

192.168.1.246

IPv4 Broadcast Address on this Subnet

192.168.1.247

Problem 5:   

Given:

Host IP Address:

128.107.0.55

Original Subnet Mask

255.255.0.0

New Subnet Mask:

255.255.255.0

 

Find:

Number of Subnet Bits

8

Number of Subnets Created

256

Number of Host Bits per Subnet

8

Number of Hosts per Subnet

254

Network Address of this Subnet

128.107.0.0

IPv4 Address of First Host on this Subnet

128.107.0.1

IPv4 Address of Last Host on this Subnet

128.107.0.254

IPv4 Broadcast Address on this Subnet

128.107.0.255

Problem 6:   

Given:

Host IP Address:

192.135.250.180

Original Subnet Mask

255.255.255.0

New Subnet Mask:

255.255.255.248

 

Find:

Number of Subnet Bits

5

Number of Subnets Created

32

Number of Host Bits per Subnet

3

Number of Hosts per Subnet

6

Network Address of this Subnet

192.135.250.176

IPv4 Address of First Host on this Subnet

192.135.250.177

IPv4 Address of Last Host on this Subnet

192.135.250.182

IPv4 Broadcast Address on this Subnet

192.135.250.183

Reflection Question

Why is the subnet mask so important when analyzing an IPv4 address?

The subnet mask determines everything about the address: the network, number of host bits, number of hosts and the broadcast address. Merely looking at an IPv4 address tells you nothing. You need the subnet mask to fill in all the important pieces of information.

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