Day 8: Internet Protocols - Part 2

Learning Objectives

• CSN-1.E: For fault-tolerant systems like the Internet: a. Describe the benefits of fault tolerance. b. Explain how a given system is fault-tolerant. c. Identify vulnerabilities to failure in a system.

Essential Questions

• How do application-level protocols enable web browsing and other Internet services?
• How do DNS and HTTP work together to deliver web content?
• How have Internet protocols evolved over time?

Materials Needed

• Presentation slides on application protocols
• Web browser with developer tools
• Protocol analysis worksheet
• DNS and HTTP simulation cards
• Exit ticket templates

Vocabulary

• HTTP (Hypertext Transfer Protocol)
• HTTPS (HTTP Secure)
• DNS (Domain Name System)
• URL (Uniform Resource Locator)
• HTML (Hypertext Markup Language)
• Client-server model
• Request-response
• API (Application Programming Interface)
• Cookie
• Status code

Procedure (50 minutes)

Opening (8 minutes)

1. Review and Connection (3 minutes)

   • Review TCP/IP and packet switching from previous lesson
   • Connect to today's focus on higher-level application protocols

2. Warm-up Activity (5 minutes)

   • Ask students to type a URL into a browser and observe what happens
   • Have them list all the steps they think occur between typing the URL and seeing the webpage
   • Create a class list of these steps
   • Introduce the focus on HTTP and DNS protocols

Main Activities (32 minutes)

3. Lecture: HTTP, DNS, and Other Application Protocols (12 minutes)

   • Explain the Domain Name System (DNS):
     • Purpose: Converting domain names to IP addresses
     • Hierarchical structure (root, TLD, domain, subdomain)
     • Distributed database system
     • Caching for efficiency
   • Explain HTTP (Hypertext Transfer Protocol):
     • Client-server model
     • Request-response pattern
     • Methods (GET, POST, etc.)
     • Status codes (200 OK, 404 Not Found, etc.)
     • Stateless nature and cookies
   • Discuss HTTPS and security:
     • Encryption of data in transit
     • Certificate verification
     • Protection against eavesdropping and tampering
   • Introduce other common application protocols:
     • SMTP/IMAP/POP (email)
     • FTP (file transfer)
     • MQTT (Internet of Things)

4. Demonstration: How Web Requests Work (8 minutes)

   • Use browser developer tools to show actual HTTP requests and responses
   • Demonstrate DNS lookup process
   • Show the components of an HTTP request:
     • Method
     • URL
     • Headers
     • Body (for POST requests)
   • Show the components of an HTTP response:
     • Status code
     • Headers
     • Body (HTML, CSS, JavaScript, etc.)
   • Illustrate how multiple requests are needed for a complete webpage
   • Demonstrate how cookies maintain state between requests

5. Activity: Analyzing Network Traffic (12 minutes)

   • Guide students in using browser developer tools
   • Have students visit different websites and analyze the network traffic
   • Students should document:
     • Number of requests made
     • Types of resources loaded (HTML, CSS, images, etc.)
     • Response codes received
     • Loading time for different resources
     • Third-party domains contacted
   • Discuss patterns and observations as a class
   • Connect observations to protocol concepts

Closing (10 minutes)

6. Discussion: Protocol Evolution (5 minutes)

   • Lead a discussion on how Internet protocols have evolved
   • Compare HTTP/1.1 vs. HTTP/2 vs. HTTP/3
   • Discuss the transition from IPv4 to IPv6
   • Explain how protocols adapt to new requirements
   • Address any misconceptions about protocol development

7. Exit Ticket: Protocol Analysis (5 minutes)

   • Students complete a worksheet analyzing a specific protocol scenario
   • Include questions about:
     • DNS resolution process
     • HTTP request and response components
     • Protocol security considerations
     • Common error scenarios
   • Collect worksheets before students leave

Assessment

• Formative: Quality of network traffic analysis
• Exit Ticket: Accuracy of protocol analysis worksheet

Differentiation

For Advanced Students

• Ask them to analyze more complex protocol interactions
• Have them explore API protocols and RESTful services
• Challenge them to explain protocol security vulnerabilities

For Struggling Students

• Focus on the most essential protocol concepts
• Provide guided analysis templates
• Use more visual aids and step-by-step guides

Homework/Extension

• Research how a specific website or service uses application protocols
• Compare different versions of a protocol and their improvements
• Create a diagram showing the complete process of loading a webpage

Teacher Notes

• Use analogies to help students understand protocols (e.g., HTTP as a conversation with rules)
• Be prepared to address questions about specific protocol details
• Make connections to students' everyday web browsing experiences
• Consider privacy implications when analyzing network traffic (use appropriate sites)
• Emphasize that understanding these protocols helps with web development and security