Lesson Notes By Weeks and Term v5 - Grade 11

Lesson Video

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Performance objectives

• Define 'protocol' and 'service'.
• Identify key internet protocols like TCP/IP, HTTP/HTTPS, DNS, SMTP, and FTP.
• Differentiate between client-server and peer-to-peer models.
• Explain the role of IP addresses and domain names.
• Describe common internet services like email and web browsing.

Lesson summary

This week, we delve into the fundamental building blocks of the internet and other networks: communication protocols and services. Understanding these concepts is crucial because they govern how devices "talk" to each other, enabling everything from browsing websites and sending emails to online banking and streaming services. In South Africa, where access to information and digital services is vital for education, economic participation, and social connection, understanding how these technologies work empowers you to be a responsible and effective digital citizen. Protocols are like the agreed-upon rules of the road for data traffic. Without them, the internet would be chaotic and unusable.

Lesson notes

What is a Protocol? A protocol is a set of rules that govern how data is transmitted between devices on a network. Think of it as a common language that computers use to understand each other.

These rules define things like: Data Format: How data is structured and organized.

Addressing: How devices identify each other.

Error Handling: How errors are detected and corrected.

Flow Control: How data transmission is regulated to prevent overwhelming the receiver.

Security: How data is protected from unauthorized access. Without protocols, devices would not be able to communicate reliably or securely.

Common Internet Protocols: TCP/IP (Transmission Control Protocol/Internet Protocol): This is the foundational protocol suite of the internet. It's actually a collection of protocols working together.

IP (Internet Protocol): Handles addressing and routing of data packets across networks. Every device on the internet has a unique IP address (like a postal address).

There are two versions in common use: IPv4 and IPv

6. IPv4 uses 32-bit addresses (e.g., 192.168.1.1), while IPv6 uses 128-bit addresses (e.g., 2001:0db8:85a3:0000:0000:8a2e:0370:7334). IPv6 was developed because the available IPv4 addresses were running out.

TCP (Transmission Control Protocol): Provides reliable, ordered delivery of data between applications. It breaks data into packets, ensures they arrive in the correct order, and re-transmits any lost packets. Think of sending a registered letter versus a regular letter; TCP is like the registered letter. HTTP/HTTPS (Hypertext Transfer Protocol/Hypertext Transfer Protocol Secure): Used for transferring web pages and other content between web servers and web browsers. HTTP is unencrypted, while HTTPS uses encryption (SSL/TLS) to secure the connection. When you see a padlock icon in your browser's address bar, it means you're using HTTPS. This is vital for protecting sensitive information like passwords and credit card details when shopping online or using online banking in South Africa.

DNS (Domain Name System): Translates domain names (e.g., www.example.com) into IP addresses (e.g., 93.184.216.34). This allows users to access websites using easy-to-remember names instead of complex IP addresses. Imagine DNS as a phone book for the internet.

SMTP (Simple Mail Transfer Protocol): Used for sending email messages between mail servers. When you send an email using Gmail, Yahoo, or a local ISP's email service, SMTP is used to transfer the message to the recipient's mail server.

FTP (File Transfer Protocol): Used for transferring files between computers over a network. It is less commonly used now due to the prevalence of cloud storage services like Google Drive and Dropbox, but it is still used for uploading files to web servers and other tasks. What is a Service? A service is an application or functionality provided over a network using one or more protocols.

Examples include: Web Browsing: Uses HTTP/HTTPS protocols to retrieve and display web pages.

Email: Uses SMTP for sending emails and POP3/IMAP for receiving emails.

File Sharing: Can use FTP or peer-to-peer (P2P) protocols like BitTorrent.

Streaming Video: Uses protocols like HTTP Live Streaming (HLS) or Dynamic Adaptive Streaming over HTTP (DASH). Client-Server vs.

Peer-to-Peer (P2P)

Network Models: Client-Server: A central server provides services to multiple clients. The client requests services from the server, and the server responds.

Examples: Web browsing (browser is the client, web server is the server), email (email client is the client, mail server is the server).

Peer-to-Peer (P2P): Each device (peer) can act as both a client and a server, sharing resources directly with other peers.

Examples: File sharing using BitTorrent, some online gaming applications.

IP Addresses and Domain Names: Every device connected to the internet has a unique IP address. This is how devices are identified and located on the network.

However, IP addresses are difficult to remember, so domain names (e.g., www.dstv.co.za) are used instead. The DNS translates domain names into IP addresses.

Example: Imagine you want to visit the website of a local South African news organization, News24 (www.news24.com). You type "www.news24.com" into your browser's address bar. Your computer sends a request to a DNS server to resolve the domain name "www.news24.com" into its corresponding IP address (e.g., 196.35.233.12). The DNS server responds with the IP address. Your browser then sends an HTTP request to the server at that IP address, requesting the News24 homepage. The News24 server sends back the HTML code for the homepage. Your browser renders the HTML code and displays the News24 homepage on your screen. If you are accessing a secure page on News24, HTTPS is used, encrypting the data transmitted between your browser and the server to protect your privacy. Guided Practice (With Solutions)

Question 1: Explain the difference between TCP and IP.