Chapter 8 Review

What area of a network can provide less stringent security so a web server is more accessible from the open Internet?

DMZ (Demilitarized zone)

What is the least number of bits you would need to borrow from the network portion of a Class B subnet mask to get at least 130 hosts per subnet?

Eight

Now you can calculate the network IDs for each subnet. Begin with the original network ID. Then in the third octet, count up by the magic number with each iteration. The last subnet's network ID will be equal to 256 minus the magic number, because you can't use 256 itself in any IP address. What is the CIDR notation for the second subnet's network ID?

172.20.16.0/20

You can now calculate the subnet mask. The default subnet mask for a Class B network is 255.255.0.0, and so the third octet is the one that will change. What is the subnet mask for these subnets, written in decimal?

255.255.240.0

Which formulas can be used to calculate the magic number? Choose two.

256 - the interesting octet; 2h

What is the formula for determining the number of possible hosts on a network?

2h - 2 = Z

While designing your network's VLAN topology, your team has decided to use a centrally managed DHCP server rather than creating a separate DHCP server for each VLAN. What software will you need in order to make the central DHCP server accessible across VLANs?

DHCP relay agent

An attacker configures a VLAN frame with two tags instead of just one. The first tag directs the frame to the authorized VLAN. After the frame enters the first VLAN, the switch appropriately removes the tag, then discovers the next tag, and sends the frame along to a protected VLAN, which the attacker is not authorized to access. What kind of attack is this?

VLAN hopping

Which hexadecimal block in an IPv6 address is used for the Subnet ID?

The fourth one

The increment will tell you by what amount to skip-count when you're listing the subnets' network IDs. There are two ways to calculate the increment: subtract the interesting octet's value from 256, or use the formula 2h. What is the increment you can use to calculate the network IDs?

16

What is the network ID with CIDR notation for the IP address 172.16.32.108 whose subnet mask is 255.255.255.0?

172.16.32.0/24

On which networking device do you configure VLANs?

Managed switches

Which VLAN is designed to support administrative access to networking devices?

Management VLAN

Which VLAN on a switch manages untagged frames?

Native VLAN

What do well-chosen subnets accomplish?

Network documentation is easier to manage.

Which of the following is not a good reason to segment a network?

To increase the number of networking devices on a network

Which port mode on a switch enables that port to manage traffic for multiple VLANs?

Trunk

Which IP addressing technique subnets a subnet to create subnets of various sizes?

VLSM (Variable Length Subnet Mask )

How many bits of a Class A IP address are used for host information?

24 bits

Subnetting operates at Layer ________ while VLANs function at Layer _______.

3, 2

Suppose your organization uses the Class B network ID of 172.20.0.0 for its entire network and wants to create 15 subnets. You first need to decide how many bits to borrow from the host address bits. Recall that you can use the formula 2n = Y. For the new subnets, how many bits must be borrowed from the host address portion? How many bits total will be used for identifying a host's subnet?

4, 20

If 20 bits are used to identify the network and subnet, that leaves 12 bits to identify each host. Using the formula 2h - 2 = Z, how many host addresses are possible in each subnet? (You might need a calculator for this step).

4094

Which IEEE standard determines how VLANs work on a network?

802.1Q