Hoja de repaso: Internet Fundamentals and Web Development

📋 Course Outline

1. Internet importance and history
2. Internet architecture and web pages
3. IP addresses and domain names
4. DNS and domain extensions
5. Packet switching on the Internet
6. World Wide Web and browsers
7. HTTP and URLs
8. Website setup steps

📖 1. Internet importance and history

🔑 Key Concepts & Definitions

• Internet : The Internet is a global system of interconnected devices that transmit and receive information.
• J.C.R Licklider : J.C.R Licklider is credited as the father of the Internet.
• ARPANET : ARPANET was the initial name used for what became the Internet.
• 24/7 connectivity : 24/7 connectivity means Internet access can happen anytime and anywhere.

📝 Essential Points

• The Internet is described as more than 50 years old, with birth year 1962.
• The lesson states that over 5 billion users are global internet users today.
• Understanding the Internet’s foundation helps you troubleshoot problems, stay secure online, and make smarter digital choices.

💡 Memory Hook

Licklider → ARPANET → Internet (think “early brain → early network → global network”).

📖 2. Internet architecture and web pages

🔑 Key Concepts & Definitions

• Server : A server is a computer connected to the Internet that stores and provides web pages.
• Web pages : Web pages are files stored on a server’s hard drive.
• Website : A website is a collection of web pages.
• Client browser : A client browser is the web application users use to access and view web information.

📝 Essential Points

• The lesson says a server can be “wireless or wire” connected to the Internet and contains web pages.
• A collection of web pages is called a website.
• Servers are identified from the client browser through the server’s IP address.
• An example IP address given for a server is 67.205.46.248.

💡 Memory Hook

Server holds pages; client asks via browser; server is found by IP.

📖 3. IP addresses and domain names

🔑 Key Concepts & Definitions

• IP address : An IP address is a unique identifier assigned to devices connected to the Internet.
• IPv4 : IPv4 is the form of IP address made of four numbers separated by periods.
• Domain name : A domain name is a name used to identify a server instead of relying on numeric IP addresses.
• Google.com : google.com is given as an example of a domain name used for a server name.

📝 Essential Points

• IPv4 uses four numbers separated by periods, and each number ranges from 0 to 255.
• The lesson explains that IP addresses are seldom used directly because remembering numbers is difficult.
• It states that servers are usually given a name such as google.com instead of using an IP directly.

💡 Memory Hook

IPv4 = 4 numbers (0–255 each).

📖 4. DNS and domain extensions

🔑 Key Concepts & Definitions

• Domain Name Service : Domain Name Service is a network service that maps domain names to IP addresses.
• .com : .com is a domain extension used for commercial organisations in the lesson’s examples.
• .edu : .edu is a domain extension used for educational institutions in the lesson’s examples.
• .edu.sg : .edu.sg is an example domain extension where sg is the country code for Singapore.

📝 Essential Points

• The lesson states that DNS maps domain names to IP addresses.
• It lists .com for commercial organisations, .edu for educational institutions, .net for network resources organisations, and .org for other non-profit making organisations.
• It explains that sg in .edu.sg is the country code for Singapore.

💡 Memory Hook

DNS answers the question: name → IP.

📖 5. Packet switching on the Internet

🔑 Key Concepts & Definitions

• Packet switching : Packet switching is the method where information is split into smaller parts for Internet transmission.
• Packets : Packets are the smaller pieces that an information message is divided into before sending.
• Source : The source is the point where information is divided into smaller bits before transmission.
• Destination : The destination is the point where received packets are put back together to form the complete information.

📝 Essential Points

• The lesson says packet switching divides information into smaller bits at the source, transmits them through the network, and reassembles them at the destination.
• The summary repeats that information is broken down in packets and later reassembled when all pieces reach the recipient.

💡 Memory Hook

Split at source → send as packets → reassemble at destination.

📖 6. World Wide Web and browsers

🔑 Key Concepts & Definitions

• World Wide Web : The World Wide Web is a service that uses the Internet and HTTP to publish and share information.
• Web browsers : Web browsers are software applications that interpret and display web information to users.
• HTTP : HTTP is used by the World Wide Web for sharing and exchanging information.
• Hypertext documents : Hypertext documents are described as the kind of documents accessed via the World Wide Web system.

📝 Essential Points

• The lesson states that you access the World Wide Web through web browsers.
• It says the World Wide Web uses the Internet and HTTP to publish and share information.
• In the lesson’s comparison, the Internet provides infrastructure for data exchange while the World Wide Web enables access to websites and web content.

💡 Memory Hook

WWW = browser-facing information layer on top of the Internet.

📖 7. HTTP and URLs

🔑 Key Concepts & Definitions

• Uniform Resource Locator : A Uniform Resource Locator is the address of a file or resource accessible on the World Wide Web.
• Protocol name : The protocol name is the part of a URL that states which protocol is used to access the resource.
• Directory/file location : The directory or file location is the optional part of a URL that points to where the resource is located.

📝 Essential Points

• The lesson defines HTTP as rules for exchanging files or information on the WWW.
• It states a URL contains the protocol name, the domain name, and an optional directory/file location.
• The example URL http://www.nyp.edu.sg/SIT/bt_main.html includes protocol http, domain www.nyp.edu.sg, and a directory/file location SIT/bt_main.html.

💡 Memory Hook

URL parts: protocol + domain + (optional) path.

📖 8. Website setup steps

🔑 Key Concepts & Definitions

• Web server : A web server is a server computer connected to the Internet that hosts the website files.
• HTML CSS JavaScript : HTML, CSS, and JavaScript are used to design and create the website before uploading it to the web server.
• Web client : A web client is the user’s web browser that accesses the website when the URL is entered.

📝 Essential Points

• The lesson’s first step is to get a web server connected to the Internet.
• It says the purchased web server has a unique IP address, with an example of 202.0.127.11.
• It states you purchase a domain name like www.nyp.edu.sg and tag it to the web server’s IP address.
• It says you design and create the website using HTML, CSS, JavaScript and upload it to the web server.
• It states the public can view the website by entering http://www.nyp.edu.sg in their web browser.

💡 Memory Hook

Server (IP) + Domain (name) + Files (HTML/CSS/JS) → Browser URL shows site.

📊 Synthesis Tables

Internet vs World Wide Web

Feature	Internet	World Wide Web
Definition	A global network of interconnected computers and devices	A system of interlinked hypertext documents accessed via the Internet
Function	Provides infrastructure for data exchange	Enables access to websites and web content
Components	Includes email, FTP, VoIP, online games, and the Web	Includes websites, web pages, multimedia content
Protocols	Used TCP/IP, FTP, SMTP, etc.	HTTP, HTTPS
Access tools	Routers, modems, switches	Web browsers (e.g., Chrome, Firefox, Safari)
Analogy	Like a highway system	Like the cars and signs that travel on the highway

⚠️ Common Pitfalls & Confusions

1. Mixing up Internet and World Wide Web: the lesson treats the Internet as infrastructure and the WWW as the website-access system over it.
2. Thinking an IP address replaces a domain name: the lesson says DNS maps domain names to IP addresses.
3. Believing servers are identified by something other than IP address: the lesson explicitly says identification happens through IP address.
4. Assuming a URL is just a website name: the lesson says it includes protocol, domain, and an optional directory/file location.
5. Forgetting that web pages live on a server’s hard drive: the lesson defines web pages as server files.
6. Confusing packet switching with file sharing: the lesson frames packet switching as dividing and reassembling data through the network.

✅ Exam Checklist

1. Define the Internet and identify ARPANET as the initial name mentioned in the lesson.
2. State that J.C.R Licklider is considered the father of the Internet.
3. Explain the role of a server in providing web pages to users.
4. Define web pages and distinguish a website as a collection of web pages.
5. Describe how a server is identified from the client browser using IP address.
6. Give the IPv4 format and the allowed range for each number.
7. Explain why IP addresses are seldom used directly and what replaces them.
8. Define Domain Name Service (DNS) as mapping domain names to IP addresses.
9. List the domain extensions .com, .edu, .net, and .org with their purposes as stated.
10. Explain what sg means in .edu.sg in the lesson’s example.
11. Describe packet switching: how information is split at the source and reassembled at the destination.
12. Define the World Wide Web (WWW) in terms of Internet use and HTTP.
13. Identify what web browsers do when accessing WWW information.
14. Define HTTP and state what a URL is.