Chapter 4 - Easy Subnetting

Question 1

Identify the four advantages of subnetting.

Answer 1

• reduced network traffic,
• optimized network performance,
• simplified management,
• facilitated spanning of large geographical distances.

Question 2

Describe the effect of the ip subnet-zero command.

Answer 2

This command allows you to use the first and last subnet in your network design.

Question 3

Identify the steps to subnet a classful network.

Answer 3

Understand how IP addressing and subnetting work. First, determine your block size by using the 256-subnet mask math. Then count your subnets and determine the broadcast address of each subnet— it is always the number right before the next subnet. Your valid hosts are the numbers between the subnet address and the broadcast address.

Question 4

Determine the valid possible block sizes.

Answer 4

The valid block sizes are always 2, 4, 8, 16, 32, 64, 128, etc. You can determine your block size by using the 256-subnet mask math.

Question 5

Describe the role of a subnet mask in IP addressing.

Answer 5

A subnet mask is a 32-bit value that allows the recipient of IP packets to distinguish the network ID portion of the IP address from the host ID portion of the IP address.

Question 6

Understand and apply the 2x – 2 formula.

Answer 6

Use this formula to determine the proper subnet mask for a particular size network given the application of that subnet mask to a particular classful network.

Question 7

Explain the impact of Classless Inter-Domain Routing (CIDR).

Answer 7

CIDR allows the creation of networks of a size other than those allowed with the classful subnetting by allowing more than the three classful subnet masks.

Question 8

You have a Class B network and need 29 subnets. What is your mask?

Answer 8

Best answer is /21 (255.255.248.0). This gives you 32 subnets.