IPv4 address structure in Computer Networks - Practice Problems & Coding Challenges

Challenge - 5 Problems

📋 Factual

intermediate

Understanding IPv4 Address Format

What is the correct format of an IPv4 address?

A Eight groups of hexadecimal numbers separated by colons

B Four groups of decimal numbers separated by dots, each ranging from 0 to 255

C A single 32-bit binary number without separators

D Four groups of decimal numbers separated by commas, each ranging from 0 to 999

💡 Hint

Think about how many parts an IPv4 address has and the range of each part.

An IPv4 address consists of four decimal numbers separated by dots. Each number is between 0 and 255 because each represents 8 bits (1 byte) of the 32-bit address.

🧠 Conceptual

intermediate

Binary Representation of IPv4 Address

How many bits are there in total in an IPv4 address, and how are they divided?

A 16 bits total, divided into two 8-bit sections

B 64 bits total, divided into eight 8-bit sections

C 32 bits total, divided into four 8-bit sections

D 128 bits total, divided into sixteen 8-bit sections

💡 Hint

Remember that each decimal number in IPv4 corresponds to 8 bits.

IPv4 addresses are 32 bits long, split into four parts of 8 bits each. Each part is represented as a decimal number from 0 to 255.

🔍 Analysis

advanced

Identifying Valid IPv4 Addresses

Which of the following IPv4 addresses is invalid?

A 256.100.50.25

B 192.168.1.1

C 10.0.0.255

D 172.16.254.3

💡 Hint

Check if each number in the address is within the allowed range.

Each part of an IPv4 address must be between 0 and 255. The number 256 is outside this range, making option A invalid.

❓ Comparison

advanced

Comparing IPv4 and IPv6 Address Lengths

How does the length of an IPv4 address compare to an IPv6 address?

A IPv4 addresses are 32 bits long; IPv6 addresses are 128 bits long

B IPv4 addresses are 128 bits long; IPv6 addresses are 32 bits long

C Both IPv4 and IPv6 addresses are 64 bits long

D IPv4 addresses are 64 bits long; IPv6 addresses are 128 bits long

💡 Hint

IPv6 was designed to provide a much larger address space than IPv4.

IPv4 addresses use 32 bits, while IPv6 addresses use 128 bits to allow for many more unique addresses.

❓ Reasoning

expert

Calculating Number of Unique IPv4 Addresses

Given the structure of an IPv4 address, how many unique addresses can be created?

A Approximately 65,536 unique addresses

B Approximately 1 million unique addresses

C Approximately 340 undecillion unique addresses

D Approximately 4.3 billion unique addresses

💡 Hint

Calculate 2 raised to the power of the total bits in an IPv4 address.

IPv4 addresses have 32 bits, so the total number of unique addresses is 2^32, which is about 4.3 billion.

Practice

1. What is the correct structure of an IPv4 address?

easy

A. Three numbers separated by dots, each from 0 to 255

B. Six numbers separated by colons, each from 0 to 65535

C. Four numbers separated by dots, each from 0 to 255

D. Four numbers separated by commas, each from 0 to 255

Solution

1. Step 1: Understand IPv4 format

   An IPv4 address consists of four parts called octets, separated by dots.

2. Step 2: Check the range of each octet

   Each octet ranges from 0 to 255, which fits in 8 bits.

3. Final Answer:

   Four numbers separated by dots, each from 0 to 255 -> Option C

4. Quick Check:

   IPv4 = 4 octets (0-255) [OK]

Hint: IPv4 always has 4 dot-separated numbers 0-255 [OK]

Common Mistakes:

• Confusing IPv4 with IPv6 format
• Using commas instead of dots
• Incorrect number of parts

2. Which of the following is a valid IPv4 address?

easy

A. 10.0.0.1

B. 192.168.1.256

C. 172.16.300.5

D. 255.255.255

Solution

1. Step 1: Check each octet's value

   Valid IPv4 octets must be between 0 and 255 inclusive.

2. Step 2: Validate each option

   A has all octets 0-255 and 4 parts (valid). B: 192.168.1.256 has 256 (invalid), C has 300 (invalid), D has only 3 parts (invalid). Only A is valid.

3. Final Answer:

   10.0.0.1 -> Option A

4. Quick Check:

   All octets 0-255 and 4 parts = valid IPv4 [OK]

Hint: Check each number is 0-255 and count 4 parts [OK]

Common Mistakes:

• Allowing numbers above 255
• Ignoring missing octets
• Confusing IPv4 with IPv6

3. What is the decimal value of the first octet in the IPv4 address 11000000.10101000.00000001.00000001?

medium

A. 255

B. 168

C. 1

D. 192

Solution

1. Step 1: Convert first octet from binary to decimal

   Binary 11000000 equals 128+64=192.

2. Step 2: Confirm decimal value

   The first octet decimal value is 192.

3. Final Answer:

   192 -> Option D

4. Quick Check:

   11000000 binary = 192 decimal [OK]

Hint: Convert binary octet to decimal by adding powers of 2 [OK]

Common Mistakes:

• Misreading binary digits
• Adding wrong powers of two
• Confusing octet positions

4. Identify the error in this IPv4 address: 256.100.50.25

medium

A. Too many octets

B. The first octet is out of range

C. Octets must be separated by commas

D. The last octet is missing

Solution

1. Step 1: Check each octet's value range

   IPv4 octets must be between 0 and 255 inclusive.

2. Step 2: Identify invalid octet

   The first octet is 256, which is outside the valid range.

3. Final Answer:

   The first octet is out of range -> Option B

4. Quick Check:

   Octet > 255 means invalid IPv4 [OK]

Hint: Octets must be 0-255; 256 is invalid [OK]

Common Mistakes:

• Thinking 256 is valid
• Confusing separators
• Ignoring octet count

5. You need to assign IP addresses to 300 devices in a network. Which of these IPv4 address ranges can you use without running out of addresses?

hard

A. 172.16.0.0 to 172.16.1.255

B. 10.0.0.0 to 10.0.0.127

C. 192.168.1.0 to 192.168.1.255

D. 192.168.0.0 to 192.168.0.100

Solution

1. Step 1: Calculate number of addresses in each range

   Range A: 256 addresses (0-255), B: 128 addresses, C: 512 addresses (two full /24 blocks), D: 101 addresses.

2. Step 2: Compare with required 300 devices

   Only range C has enough addresses (512) to cover 300 devices.

3. Final Answer:

   172.16.0.0 to 172.16.1.255 -> Option A

4. Quick Check:

   More than 300 addresses needed, only C fits [OK]

Hint: Count addresses: 256 per block; need ≥300 [OK]

Common Mistakes:

• Assuming 256 addresses cover 300 devices
• Ignoring address range size
• Confusing IP blocks