COMMUNICATION AND NETWORK TECHNOLOGIES

1. Definition, Advantages, and Disadvantages of a Network

• Definition: A network is a group of interconnected computers and devices that communicate with each other to share resources and data.

• Advantages:

○ Resource sharing (e.g., printers, files)

○ Centralized data management

○ Enhanced communication (e.g., email, chat)

○ Cost efficiency by sharing hardware and software

• Disadvantages:

○ Security risks (e.g., unauthorized access)

○ Network failures can disrupt operations

○ Initial setup costs can be high

○ Maintenance and administration require expertise

2. Network Components

• Server:

○ Function: Manages network resources and provides services to client devices.

○ Example: File server, email server.

• Network Operating System (NOS):

○ Function: Software that controls network resources and provides services to clients.

○ Example: Windows Server, Linux.

• Network Interface Card (NIC):

○ Function: Hardware that connects a computer to a network.

○ Example: Ethernet card, Wi-Fi adapter.

• Switch:

○ Function: Connects devices within a LAN and directs data to its destination.

○ Example: Cisco switch.

• Router:

○ Function: Directs data between different networks, such as between a home network and the internet.

○ Example: Home Wi-Fi router.

3. Terminology

• Bandwidth: The amount of data that can be transmitted over a network in a given time period.

• Broadband: High-speed internet access that is always on and faster than traditional dial-up.

• Range: The distance over which a wireless signal can effectively transmit data.

• Backbone: The main connection in a network that carries the most data traffic.

4. Communication Media

• Wired:

○ Advantages: Reliable, high speed, secure.

○ Disadvantages: Expensive to install, limited mobility.

○ Example: Ethernet cables (Cat5, Cat6).

• Wireless:

○ Advantages: Easy to install, mobile, flexible.

○ Disadvantages: Susceptible to interference, less secure.

○ Example: Wi-Fi, Bluetooth.

5. Types of Networks

• Personal Area Network (PAN):

○ Definition: Small network, typically within a range of a few meters.

○ Example: Bluetooth devices.

• Home Area Network (HAN):

○ Definition: Network within a home connecting personal devices.

○ Example: Wi-Fi network in a house.

• Local Area Network (LAN):

○ Definition: Network in a limited area like an office or school.

○ Example: Office network.

• Wide Area Network (WAN):

○ Definition: Network that covers a large geographic area.

○ Example: The internet.

• Wireless Local Area Network (WLAN):

○ Definition: A LAN that uses wireless technology.

○ Example: Wi-Fi network in a coffee shop.

6. Physical Layout – Star Topology

• Definition: A network layout where all devices are connected to a central hub or switch.

• Advantages: Easy to install and manage, failure of one device doesn’t affect others.

• Disadvantages: If the central hub fails, the entire network is affected.

7. Internet vs Intranet vs Extranet

• Internet: Global network accessible to anyone.

• Intranet: Private network accessible only to an organization’s members.

• Extranet: Private network accessible to certain external users with permissions.

8. Virtual Private Networks (VPN)

• Definition: A secure, encrypted connection over the internet that allows remote users to access a private network.

• Advantages: Provides security, hides user’s IP address.

• Disadvantages: Can slow down internet speed, requires configuration.

9. Location-Based Computing

• Definition: Technology that uses geographic data to provide services or information based on a user’s location.

• Example: GPS navigation, location-based marketing.

10. Network Architecture

• Client vs Peer:

○ Client: A device that requests resources from a server.

○ Peer: A device that acts both as a client and a server in a network.

• Client-Server Architecture:

○ Definition: A network where multiple clients request and receive services from a central server.

○ Advantages: Centralized management, security.

○ Disadvantages: Server failure affects all clients.

• Peer-to-Peer Architecture:

○ Definition: A network where each device can act as both a client and a server.

○ Advantages: Simple to set up, no need for a central server.

○ Disadvantages: Less secure, harder to manage.

11. Remote Desktop Access vs VPN

• Remote Desktop Access:

○ Definition: Allows a user to remotely control another computer over a network.

○ Example: TeamViewer, Windows Remote Desktop.

• VPN:

○ Definition: Provides a secure connection to a private network over the internet.

○ Example: NordVPN, Cisco VPN.

12. BitTorrent

• Definition: A peer-to-peer file-sharing protocol used to distribute large amounts of data over the internet.

• Advantages: Efficient for large file transfers.

• Disadvantages: Can be used for illegal file sharing, security risks.

1. Connecting to the Internet

• Definition: The process of linking a device to the internet to access online resources and services.

• Methods:

○ Wired: Ethernet cables for stable and fast connections.

○ Wireless: Wi-Fi, cellular networks, and satellite connections.

• Advantages:

○ Access to vast information resources.

○ Enables communication and remote work.

• Disadvantages:

○ Security risks like hacking and malware.

○ Requires stable infrastructure and can be costly.

2. Cellular

• Definition: A wireless communication technology that uses cell towers to provide mobile access to voice, text, and internet services.

• Function: Enables mobile internet access and communication via mobile devices.

• Advantages:

○ Mobility: Access the internet from anywhere within coverage.

○ Expanding coverage areas.

• Disadvantages:

○ Signal strength varies with location.

○ Data costs can be high.

• Examples: 3G, 4G, LTE, 5G networks.

3. Hotspots

• Definition: Public or private areas where Wi-Fi is available for internet access.

• Function: Provides wireless internet access to devices within a certain range.

• Advantages:

○ Convenient and often free in public areas.

○ No need for cables.

• Disadvantages:

○ Security risks, especially in public hotspots.

○ Limited range and speed.

• Examples: Coffee shops, airports, personal mobile hotspots.

4. FTTH (Fibre to the Home): Shaping and Throttling

• FTTH Definition: High-speed internet access delivered via fiber optic cables directly to homes.

• Shaping: Managing internet traffic to prioritize certain types of data (e.g., streaming).

• Throttling: Intentionally slowing down internet speed during peak usage to manage network congestion.

• Advantages:

○ Fast and reliable internet speed.

○ Supports high-bandwidth applications (e.g., HD streaming).

• Disadvantages:

○ Can be expensive to install.

○ Throttling can affect user experience.

• Example: Vumatel, Openserve in South Africa.

5. Mobile/Smartphone Technology

• Mobile Device Description & Features:

○ Definition: Handheld devices with computing capabilities, such as smartphones and tablets.

○ Features: Touchscreens, cameras, GPS, apps, sensors (e.g., accelerometer, gyroscope).

• Advantages:

○ Portable and multifunctional.

○ Access to apps and the internet on the go.

• Disadvantages:

○ Limited battery life.

○ Security vulnerabilities.

• Examples: iPhone, Samsung Galaxy, Huawei.

6. Mobile Browsers & Apps

• Mobile Browsers: Software for accessing the web on mobile devices (e.g., Chrome, Safari).

• Apps: Software applications designed to perform specific tasks on mobile devices.

• Appification: The trend of using apps for specific functions instead of websites.

• Advantages:

○ Apps are optimized for mobile use.

○ Often faster and more user-friendly than browsers.

• Disadvantages:

○ Apps require installation and updates.

○ Limited storage can restrict the number of apps.

• Examples: WhatsApp (messaging), Instagram (social media), Google Maps (navigation).

7. Microsoft Outlook App vs Access Through a Web Browser

• Outlook App:

○ Function: Dedicated email app with integrated calendar, tasks, and contacts.

○ Advantages: Offline access, push notifications, better integration with mobile OS.

○ Disadvantages: Requires installation, takes up storage space.

• Access Through a Web Browser:

○ Function: Access email via the internet without needing to install an app.

○ Advantages: No installation needed, accessible from any device with a browser.

○ Disadvantages: Requires internet connection, fewer features compared to the app.

8. Mobile/Wireless e-Communication

• Email: Sending and receiving messages electronically.

○ Advantages: Formal, supports attachments.

○ Disadvantages: Not instant, can be spammed.

• SMS: Short Message Service for sending text messages.

○ Advantages: Instant, widely supported.

○ Disadvantages: Limited character count.

• IM (Instant Messaging): Real-time text communication (e.g., WhatsApp, Telegram).

○ Advantages: Instant, supports multimedia.

○ Disadvantages: Requires an internet connection.

• Blog: A regularly updated website or web page, typically run by an individual or small group.

○ Advantages: Easy to publish content.

○ Disadvantages: Can be time-consuming to maintain.

• Microblogging: Short-form content sharing (e.g., Twitter).

○ Advantages: Quick updates, easy to follow.

○ Disadvantages: Limited content depth.

• Vlog: A blog in video format (e.g., YouTube).

○ Advantages: Visual engagement.

○ Disadvantages: Requires video editing skills.

• Podcast: Audio content shared online.

○ Advantages: Can be consumed while multitasking.

○ Disadvantages: Requires audio production skills.

• Vodcast: A video podcast.

○ Advantages: Combines visual and audio content.

○ Disadvantages: High production cost.

• Video Conferencing: Real-time video meetings over the internet (e.g., Zoom, Skype).

○ Advantages: Remote communication, collaboration.

○ Disadvantages: Requires good internet connection, can be less personal.

9. e-Learning

• Definition: The use of electronic media and devices for education and training.

• Advantages:

○ Flexible learning schedules.

○ Access to a wide range of resources.

• Disadvantages:

○ Requires self-discipline.

○ Limited interaction with instructors and peers.

• Examples: Online courses, virtual classrooms, educational apps.

10. Online Storage

• Definition: Storing data on the internet through cloud services.

• Advantages:

○ Accessible from anywhere with an internet connection.

○ Automatic backups and data synchronization.

• Disadvantages:

○ Requires a reliable internet connection.

○ Potential security and privacy risks.

• Examples: Google Drive, Dropbox, OneDrive.

11. Protocols - Descriptions

• IP (Internet Protocol): Rules for routing and addressing packets of data so they can travel across networks and arrive at the correct destination.

• SMTP (Simple Mail Transfer Protocol): Used to send emails.

• POP3 (Post Office Protocol 3): Downloads emails from the server to the client and deletes them from the server.

• IMAP (Internet Message Access Protocol): Synchronizes email across multiple devices, leaving the email on the server.

• HTTP (Hypertext Transfer Protocol): The foundation of data communication on the web.

• HTTPS (Hypertext Transfer Protocol Secure): Secure version of HTTP, encrypting data between the browser and the server.

• VoIP (Voice over Internet Protocol): Technology that allows voice calls using an internet connection instead of a traditional phone line.

○ Advantages: Lower cost, especially for international calls.

○ Disadvantages: Dependent on internet quality.

○ Examples: Skype, WhatsApp calls, Zoom.