Port numbers and multiplexing in Computer Networks - Mini Project: Build & Apply

Understanding Port Numbers and Multiplexing

📖 Scenario: You are learning how computers use port numbers to manage multiple communication channels at the same time. Imagine a busy post office where many letters arrive and must be sorted to different departments. Port numbers help computers know which program should get which message.

🎯 Goal: Build a simple table that lists common port numbers and their services, then create a small example showing how multiplexing allows multiple services to run on one computer using different ports.

📋 What You'll Learn

Create a dictionary called common_ports with exact port numbers and service names

Add a variable called max_ports to represent the maximum number of ports a computer can use

Write a loop using for port, service in common_ports.items() to list all ports and their services

Add a final statement that explains multiplexing using the max_ports variable

💡 Why This Matters

🌍 Real World

Port numbers help computers and servers manage many network connections at once, like sorting mail to the right departments.

💼 Career

Understanding ports and multiplexing is essential for network administrators, cybersecurity experts, and software developers working with internet protocols.

1

Create a dictionary of common port numbers

Create a dictionary called common_ports with these exact entries: 80: 'HTTP', 443: 'HTTPS', 25: 'SMTP', 22: 'SSH', and 53: 'DNS'.

Computer Networks

# Create the dictionary common_ports with the specified port-service pairs
# Your code here

Need a hint?

Use curly braces {} to create a dictionary with port numbers as keys and service names as values.

2

Add a variable for maximum ports

Add a variable called max_ports and set it to 65535, which is the maximum number of ports available on a computer.

Computer Networks

common_ports = {80: 'HTTP', 443: 'HTTPS', 25: 'SMTP', 22: 'SSH', 53: 'DNS'}
# Add the max_ports variable below
# Your code here

Need a hint?

Just assign the number 65535 to the variable max_ports.

3

List all ports and their services

Write a for loop using for port, service in common_ports.items() to iterate over the dictionary and create a list called port_list that contains strings in the format "Port {port} is used for {service}".

Computer Networks

common_ports = {80: 'HTTP', 443: 'HTTPS', 25: 'SMTP', 22: 'SSH', 53: 'DNS'}
max_ports = 65535
# Create port_list using a for loop below
# Your code here

Need a hint?

Use a for loop to go through each port and service, then add a formatted string to the list.

4

Explain multiplexing with max_ports

Add a variable called multiplexing_explanation and set it to the string "Multiplexing allows multiple services to use different ports up to {max_ports} ports on one computer." using an f-string.

Computer Networks

common_ports = {80: 'HTTP', 443: 'HTTPS', 25: 'SMTP', 22: 'SSH', 53: 'DNS'}
max_ports = 65535
port_list = []
for port, service in common_ports.items():
    port_list.append(f"Port {port} is used for {service}")
# Add multiplexing_explanation variable below
# Your code here

Need a hint?

Use an f-string to include the max_ports variable inside the explanation string.