CIDR notation in Computer Networks - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to represent the CIDR notation for the IP address 192.168.1.0 with a subnet mask of 24 bits.

Computer Networks

cidr = "192.168.1.0/[1]"

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A16

B8

C32

D24

Attempts:

3 left

💡 Hint

Common Mistakes

Using the subnet mask in decimal form instead of the number of bits.

Confusing the number of bits with the number of octets.

The CIDR notation uses a slash followed by the number of bits in the subnet mask. For a common subnet mask of 255.255.255.0, the number of bits is 24.

2fill in blank

medium

Complete the code to calculate the number of possible hosts in a subnet given the CIDR prefix length.

Computer Networks

hosts = 2**(32 - [1]) - 2

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A24

B16

C28

D30

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting to subtract 2 for network and broadcast addresses.

Using the prefix length directly instead of subtracting from 32.

The number of hosts is calculated by subtracting the prefix length from 32 (total bits in IPv4), then raising 2 to that power and subtracting 2 for network and broadcast addresses.

3fill in blank

hard

Fix the error in the code that converts a CIDR prefix length to a subnet mask in dotted decimal format.

Computer Networks

subnet_mask = '.'.join(str((0xffffffff << (32 - [1]) >> i) & 0xff) for i in [24,16,8,0])

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Amask_length

Bcidr

Cprefix_length

Dsubnet_bits

Attempts:

3 left

💡 Hint

Common Mistakes

Using undefined variable names.

Mixing variable names that represent different concepts.

The variable representing the CIDR prefix length should be named consistently. Here, 'prefix_length' is the correct variable to use.

4fill in blank

hard

Fill both blanks to create a dictionary comprehension that maps CIDR prefixes to their subnet masks in dotted decimal format for prefixes 24 and 16.

Computer Networks

cidr_to_mask = {prefix: '.'.join(str((0xffffffff << (32 - prefix) >> i) & 0xff) for i in [1]) for prefix in [2]

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A[24, 16, 8, 0]

B[16, 24]

C[0, 8, 16, 24]

D[8, 16]

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up the order of bit shifts.

Using incorrect prefix lists.

The bit shifts for each octet are 24, 16, 8, and 0. The prefixes to map are 24 and 16.

5fill in blank

hard

Fill all three blanks to create a dictionary comprehension that maps CIDR prefixes to the number of hosts available in each subnet for prefixes 28, 26, and 24.

Computer Networks

hosts_per_subnet = {prefix: 2**(32 - [1]) - [2] for prefix in [3]

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Aprefix

B2

C[28, 26, 24]

D32

Attempts:

3 left

💡 Hint

Common Mistakes

Using the wrong variable name for the prefix.

Forgetting to subtract 2 from the total hosts.

Using incorrect prefix lists.

The variable 'prefix' is used for each CIDR prefix. The number 2 is subtracted to exclude network and broadcast addresses. The prefixes are 28, 26, and 24.