Question

Which of the following is a correct form of CIDR notation?

A) 192.168.1.1/24
B) 255.255.255.0/8
C) 172.16.0.1/16
D) 10.0.0.0/32

Answer 1

Answer: The correct form of CIDR notation is A) 192.168.1.1/24.

Step-by-step explanation:

CIDR notation is used to represent IP addresses and their associated subnet masks. It consists of the IP address followed by a forward slash (/) and a number that indicates the number of network bits in the subnet mask.

Let's break down the options:

A) 192.168.1.1/24: This is the correct form of CIDR notation. It represents an IP address of 192.168.1.1 with a subnet mask of 24 bits. The subnet mask indicates that the first 24 bits of the IP address are the network portion, while the remaining 8 bits are the host portion.

B) 255.255.255.0/8: This is not the correct form of CIDR notation. The subnet mask 255.255.255.0 represents a Class C network with a subnet mask of 24 bits, not 8 bits.

C) 172.16.0.1/16: This is not the correct form of CIDR notation. The subnet mask 172.16.0.1 represents a Class B network with a subnet mask of 16 bits, not 24 bits.

D) 10.0.0.0/32: This is not the correct form of CIDR notation. The subnet mask 10.0.0.0 represents a Class A network with a subnet mask of 8 bits, not 32 bits.

In summary, the correct form of CIDR notation is A) 192.168.1.1/24, where the IP address is 192.168.1.1 and the subnet mask is 24 bits.

Answer 2

The correct CIDR notation among the options is A) 192.168.1.1/24, which correctly matches an IP address to a subnet mask indicating use of 24 bits for the network part.

Step-by-step explanation:

The correct form of Classless Inter-Domain Routing (CIDR) notation in the options provided is A) 192.168.1.1/24. CIDR is a method for allocating IP addresses and IP routing that is more flexible than the old system of network classes. It is represented as an IP address, a slash, and a number - the IP address denotes the network boundary, and the number (after the slash) indicates the length of the subnet mask; that is, how many bits are used for the network portion.

Let's analyze the options provided:

• A) 192.168.1.1/24 is correct because it shows a typical private IP address with a subnet mask indication that 24 bits are used for the network part, with the last 8 bits (since there are 32 bits in total in an IPv4 address) for the host part.
• B) 255.255.255.0/8 is incorrect because the subnet mask shown does not match the CIDR suffix. A /8 would mean only the first 8 bits are used for the network, which corresponds to 255.0.0.0, not 255.255.255.0.
• C) 172.16.0.1/16 would not typically use a host address (172.16.0.1) - instead, you would see a network address like 172.16.0.0/16.
• D) 10.0.0.0/32 is not correct because /32 signifies a single IP address, which is not useful for a network range.

CIDR is a key concept in networking that allows for efficient allocation of IP addresses and routing.