Presentation

2.2 The Internet

2.2.1 Differences between the Internet and the World Wide Web

• Internet:

  • A massive network of networks consisting of various computers and electronic devices.

  • Stands for "interconnected network".

  • Utilizes Transmission Control Protocol (TCP) and Internet Protocol (IP).

• World Wide Web (WWW):

  • A collection of multimedia web pages stored on websites.

  • Accesses information through the Internet using HTTP(S) protocols.

Key Terms

• Internet: Network comprised of devices using TCP/IP protocols.

• World Wide Web (WWW): Set of multimedia documents accessible via the Internet.

• HyperText Mark-up Language (HTML): Language for designing web pages and writing HTTP(S) protocols.

• Uniform Resource Locator (URL): Address specifying location of a web page.

• Web Browser: Software that connects to Domain Name System (DNS) and interprets web data.

• Internet Service Provider (ISP): Company providing Internet access, typically for a monthly fee.

• Public Switched Telephone Network (PSTN): Network for traditional phone calls and faxes.

• Voice over Internet Protocol (VoIP): Technology converting voice into digital data for transmission over the Internet.

• Internet Protocol (IP): Addresses devices on the Internet using IPv4 or IPv6 formats.

IP Addressing

• IPv4: Uses 32 bits for addressing (e.g., 200.21.100.6).

• CIDR (Classless Inter-Domain Routing): Improves IPv4 flexibility.

• IPv6: Newer protocol using 128 bits (e.g., A8F0:7FFF:F0F1:F000:3DD0:256A:22FF:AA00).

• Zero Compression: Method to shorten IPv6 addresses by replacing groups of zeroes with a double colon (::).

• Sub-netting: Dividing networks into smaller sub-networks for management and efficiency.

• Public IP Address: Assigned by the ISP for devices' identification on the Internet.

• Private IP Address: Reserved for internal network use behind routers.

Domain Name System (DNS)

• Translates domain names into IP addresses, allowing easy access without memorizing numerical addresses.

2.2.2 Hardware and Software Needed to Support the Internet

• Requirements:

  • Device (Computer, tablet, mobile)

  • Connection (telephone line or mobile network)

  • Router (wired or wireless)

  • Internet Service Provider (ISP)

  • Web Browser

• Network Connection:

  • PSTN connects devices across distances; fiber optic cables have replaced copper for improved performance.

  • High-speed broadband facilitates wireless local area networks (WLANs).

Internet Communication Technologies

• VoIP converts sound and video into digital packets; utilizes packet switching allowing data to travel efficiently without dedicated lines.

• Cellular Networks: Mobile devices connect through cellular providers acting as ISPs.

• Satellite Communications: Extends network coverage over vast distances, with different orbits (GEO, MEO, LEO) providing specific functionalities.

Comparison: PSTN vs. Internet Phone Calls

• PSTN:

  • Connection is constant until hang-up; operational during power cuts.

  • Circuit switching maintains a dedicated circuit during calls.

• Internet Calls:

  • Connection exists only during communication; uses packet switching for data transmission.

  • Efficient use of bandwidth as only active data is transmitted.

2.2.3 IP Addresses

Protocols on the Internet

• TCP/IP Protocols govern communication over the Internet.

• IPv4 Addressing:

  • 32-bit addressing structure using groups of 8 bits (e.g., 254.0.128.77).

  • Classifies networks: Class A (very large) to Class C (small networks).

IPv6 Addressing

• Advantages of IPv6:

  • Supports a larger address space and complex addressing.

  • Eliminates the need for Network Address Translation (NAT).

  • Built-in authentication and efficient routing.

Zero Compression Example

• Example of zero compression for IPv6 addresses to reduce length and complexity.

Sub-netting

• Divides local area networks into smaller segments for reduced traffic and simplified management.

Private vs. Public IP Addresses

• Private Addresses reserved for internal use; non-accessible externally.

• Public Addresses identified by ISPs for external accessibility.

2.2.4 Uniform Resource Locators (URLs)

• Web browsers utilize URLs to access web pages.

• Components of a URL:

  • Protocol (http/https)

  • Domain name

  • Optional path/filename.

URL Example

• Format: http://www.hoddereducation.co.uk/computerscience

2.2.5 Domain Name Service (DNS)

• Translates user-friendly domain names into machine-readable IP addresses.

• Involves a process of requesting and caching databases of URLs by DNS servers.

2.2.6 Scripting in HTML

Client-Side vs. Server-Side Scripts

• JavaScript (Client-Side): Runs on the user's computer; processes data from the server's response.

• PHP (Server-Side): Code executed on the server, results sent to the client.

Examples of Scripts

• Sample JavaScript code checks temperature and provides a response based on the input.

• Sample PHP code illustrates server-side processing and output handling.

Conclusion

• Both programming languages are vital for creating dynamic web applications that enhance user interaction and management.