MAC addressing in Computer Networks - Mini Project: Build & Apply

Understanding MAC Addressing

📖 Scenario: You are learning about how devices on a local network identify each other using MAC addresses. Each device has a unique MAC address that helps in communication within the network.

🎯 Goal: Build a simple list of devices with their MAC addresses, set a filter to find devices from a specific manufacturer, and then extract those devices' MAC addresses.

📋 What You'll Learn

Create a dictionary called devices with device names as keys and their MAC addresses as values.

Create a variable called manufacturer_prefix that holds the first three pairs of a MAC address to filter devices.

Use a dictionary comprehension called filtered_devices to select devices whose MAC addresses start with manufacturer_prefix.

Add a final step to create a list called filtered_mac_addresses containing only the MAC addresses from filtered_devices.

💡 Why This Matters

🌍 Real World

Network administrators use MAC addresses to identify and manage devices on a local network.

💼 Career

Understanding MAC addressing is essential for roles in IT support, network administration, and cybersecurity.

1

Create the devices dictionary

Create a dictionary called devices with these exact entries: 'Laptop': '00:1A:2B:3C:4D:5E', 'Smartphone': '00:1A:2B:6F:7G:8H', 'Printer': '11:22:33:44:55:66', 'Tablet': '00:1A:2B:9J:0K:1L'.

Computer Networks

# Create the devices dictionary with device names and MAC addresses
# Your code here

Hint

Use curly braces to create a dictionary. Each device name is a key, and its MAC address is the value as a string.

2

Set the manufacturer prefix

Create a variable called manufacturer_prefix and set it to the string '00:1A:2B' to represent the manufacturer part of the MAC address.

Computer Networks

devices = {
    'Laptop': '00:1A:2B:3C:4D:5E',
    'Smartphone': '00:1A:2B:6F:7G:8H',
    'Printer': '11:22:33:44:55:66',
    'Tablet': '00:1A:2B:9J:0K:1L'
}
# Create the manufacturer_prefix variable
# Your code here

Hint

Assign the string '00:1A:2B' to the variable manufacturer_prefix.

3

Filter devices by manufacturer prefix

Use a dictionary comprehension to create a new dictionary called filtered_devices that includes only the devices from devices whose MAC addresses start with manufacturer_prefix. Use for device, mac in devices.items() and check if mac.startswith(manufacturer_prefix).

Computer Networks

devices = {
    'Laptop': '00:1A:2B:3C:4D:5E',
    'Smartphone': '00:1A:2B:6F:7G:8H',
    'Printer': '11:22:33:44:55:66',
    'Tablet': '00:1A:2B:9J:0K:1L'
}
manufacturer_prefix = '00:1A:2B'
# Create filtered_devices dictionary using dictionary comprehension
# Your code here

Hint

Use dictionary comprehension with for device, mac in devices.items() and if mac.startswith(manufacturer_prefix).

4

Extract filtered MAC addresses

Create a list called filtered_mac_addresses that contains only the MAC addresses from filtered_devices. Use a list comprehension to get the values from filtered_devices.

Computer Networks

devices = {
    'Laptop': '00:1A:2B:3C:4D:5E',
    'Smartphone': '00:1A:2B:6F:7G:8H',
    'Printer': '11:22:33:44:55:66',
    'Tablet': '00:1A:2B:9J:0K:1L'
}
manufacturer_prefix = '00:1A:2B'
filtered_devices = {device: mac for device, mac in devices.items() if mac.startswith(manufacturer_prefix)}
# Create filtered_mac_addresses list with MAC addresses from filtered_devices
# Your code here

Hint

Use list comprehension to get all MAC addresses from filtered_devices.values().

Practice

1. What does a MAC address uniquely identify in a computer network?

easy

A. A network protocol type

B. An IP address on the internet

C. A website domain name

D. A device on a local network

Solution

1. Step 1: Understand the role of MAC addresses

   A MAC address is a unique identifier assigned to network interfaces for communications on the physical network segment.

2. Step 2: Identify what MAC addresses represent

   They identify devices on a local network, not IP addresses or domain names.

3. Final Answer:

   A device on a local network -> Option D

4. Quick Check:

   MAC address = device ID on local network [OK]

Hint: MAC addresses identify devices locally, not IPs or domains [OK]

Common Mistakes:

• Confusing MAC address with IP address
• Thinking MAC identifies websites
• Assuming MAC is a protocol

2. Which of the following is the correct format of a MAC address?

easy

A. 00:1A:2B:3C:4D:5E

B. 192.168.1.1

C. 255.255.255.0

D. http://192.168.1.1

Solution

1. Step 1: Recognize MAC address format

   MAC addresses are shown as six pairs of hexadecimal numbers separated by colons or dashes.

2. Step 2: Match the correct format

   00:1A:2B:3C:4D:5E matches this format: six pairs separated by colons with hex digits.

3. Final Answer:

   00:1A:2B:3C:4D:5E -> Option A

4. Quick Check:

   MAC format = hex pairs separated by colons [OK]

Hint: Look for six hex pairs separated by colons or dashes [OK]

Common Mistakes:

• Confusing MAC with IP address format
• Including URL or protocol parts
• Using decimal numbers instead of hex

3. Given the MAC address AC:DE:48:00:11:22, which part typically identifies the manufacturer?

medium

A. 00:11:22

B. 48:00:11

C. AC:DE:48

D. DE:48:00

Solution

1. Step 1: Understand MAC address structure

   The first three pairs (first 24 bits) of a MAC address identify the manufacturer, called the OUI (Organizationally Unique Identifier).

2. Step 2: Identify the first three pairs

   In AC:DE:48:00:11:22, the first three pairs are AC:DE:48, which represent the manufacturer.

3. Final Answer:

   AC:DE:48 -> Option C

4. Quick Check:

   First 3 pairs = manufacturer ID [OK]

Hint: First 3 hex pairs in MAC show manufacturer [OK]

Common Mistakes:

• Choosing last three pairs as manufacturer
• Mixing pairs in the middle
• Not knowing OUI meaning

4. A network admin sees a MAC address written as 00-1G-2B-3C-4D-5E. What is wrong with this MAC address?

medium

A. It is missing pairs

B. It has an invalid character 'G'

C. It uses colons instead of dashes

D. It has too many pairs

Solution

1. Step 1: Check valid characters in MAC address

   MAC addresses use hexadecimal digits: 0-9 and A-F only.

2. Step 2: Identify invalid character

   The character 'G' is not a valid hex digit, so the MAC address is invalid.

3. Final Answer:

   It has an invalid character 'G' -> Option B

4. Quick Check:

   Hex digits only: 0-9, A-F [OK]

Hint: MAC uses hex digits only; watch for invalid letters [OK]

Common Mistakes:

• Ignoring invalid hex characters
• Confusing dashes and colons as errors
• Counting pairs incorrectly

5. You want to filter a list of devices to only those from a specific manufacturer with OUI 00:1A:2B. Which method best uses MAC addresses to do this?

hard

A. Check if the MAC address starts with '00:1A:2B'

B. Check if the MAC address ends with '00:1A:2B'

C. Check if the MAC address contains '2B:00:1A'

D. Check if the MAC address has '00:1A:2B' anywhere in the middle

Solution

1. Step 1: Understand OUI position in MAC address

   The OUI is always the first three pairs of the MAC address, identifying the manufacturer.

2. Step 2: Choose the correct filtering method

   To filter devices by manufacturer, check if the MAC address starts with the OUI '00:1A:2B'.

3. Final Answer:

   Check if the MAC address starts with '00:1A:2B' -> Option A

4. Quick Check:

   OUI = start of MAC address [OK]

Hint: Filter by checking MAC start for OUI [OK]

Common Mistakes:

• Checking MAC end instead of start
• Looking for OUI in the middle
• Assuming OUI can be anywhere