1.6 IPv4 Addressing and Subnetting

Question 1

Define:

IPv4 addressing

Answer 1

A system used to assign 32-bit addresses to devices on a network.

IPv4 addresses are divided into four octets, written in dotted decimal format (e.g., 192.168.1.1).

Question 2

True or False:

The IPv4 address 192.168.1.256 is valid.

Answer 2

False

Each octet in an IPv4 address must be between 0 and 255, so 192.168.1.256 is invalid.

Question 3

Why is subnetting important?

Answer 3

It divides large networks into smaller, efficient sub-networks.

It reduces broadcast domains, optimizes IP usage, and improves network management.

Question 4

What is the purpose of a subnet mask?

Answer 4

It separates the network and host portions of an IP address.

The subnet mask helps routers and devices understand which part of the address is used for the network and which part for the host.

Question 5

What address is used to send data to all hosts in a subnet?

Answer 5

Broadcast address

The broadcast address is the last address in a subnet. It is used to send packets to all devices within the same network.

Question 6

What is the default subnet mask for a Class C IPv4 address?

Answer 6

255.255.255.0

Class C addresses use the subnet mask 255.255.255.0, providing up to 254 usable host addresses.

Question 7

Fill in the blank:

The subnet mask 255.255.255.192 corresponds to a prefix length of ________.

Answer 7

/26

A /26 subnet mask allows for 64 addresses, with 62 usable host addresses.

Question 8

How do you calculate the number of usable host addresses in a subnet?

Answer 8

Subtract 2 from the total addresses in the subnet.

The formula is (2^N) - 2, where N is the number of host bits. The two addresses are reserved for the network and broadcast.

Question 9

True or False:

A subnet mask of 255.255.255.128 provides 128 usable host addresses.

Answer 9

False

A /25 subnet mask (255.255.255.128) provides 126 usable host addresses, not 128.

Question 10

You need to divide 192.168.1.0/24 into 4 subnets. What subnet mask will you use?

Answer 10

255.255.255.192

A /26 subnet mask (255.255.255.192) divides the /24 network into 4 subnets.

Question 11

Fill in the blank:

The IPv4 address 10.10.10.10/8 belongs to class _____.

Answer 11

A

Class A addresses range from 1.0.0.0 to 127.255.255.255, with a default subnet mask of 255.0.0.0.

Question 12

True or False:

The subnet mask 255.255.255.248 provides 8 usable host addresses.

Answer 12

False

A /29 subnet mask (255.255.255.248) provides 6 usable host addresses, not 8.

Question 13

What is the network address of 192.168.1.20/24?

Answer 13

192.168.1.0

The network address is the lowest address in the subnet, used to represent the network itself.

Question 14

You have an IP address of 192.168.2.0/28. How many usable host addresses do you have?

Answer 14

14

A /28 subnet mask (255.255.255.240) allows for 16 addresses, with 14 usable for hosts.

Question 15

Define:

A subnet mask of 255.255.255.252.

Answer 15

This is a /30 subnet mask with 4 addresses, 2 usable for hosts.

/30 subnets are commonly used for point-to-point links between two devices.

Question 16

True or False:

The first IP address in a subnet is reserved as the network address.

Answer 16

True

The first IP address in a subnet represents the network address, which is not assigned to a host.

Question 17

What does CIDR stand for, and how is it used in subnetting?

Answer 17

Classless Inter-Domain Routing

CIDR uses variable-length subnet masks (VLSM), allowing more efficient IP address allocation and avoiding the limitations of class-based subnetting.