Key Terminology

• Network: A group of connected devices that can share resources and communicate.

• LAN (Local Area Network): Covers a small geographical area, such as a home or office.

• WAN (Wide Area Network): Connects multiple LANs over a larger geographical area.

• Router: A device that connects networks and directs data between them.

• Switch: A device within a network that directs data to the appropriate device.

• Transmission Media: The physical or wireless methods used to transmit data (e.g., copper cables, fibre optics, Wi-Fi).

Key Ideas

1. Local Area Networks (LANs):

   • Typically used in small areas like schools, homes, hospitals or offices.

   • The organisation owns all the network infrastructure.

   • Wired connections use copper or fibre optic cables, while wireless LANs use Wi-Fi.

2. Wide Area Networks (WANs):

   • Connects LANs over large distances, such as between cities or countries.

   • Infrastructure is leased from telecommunication companies.

   • Uses telephone lines, fibre optics, or satellite links for connections.

3. Advantages of Networking:

   • Easy file and resource sharing.

   • Centralised control of security, software updates, and backups.

   • Simplified communication through email and social media.

4. Disadvantages of Networking:

   • Increased security risks (e.g., malware, viruses).

   • Potential slowdowns when many devices are connected.

   • Dependency on servers; if a server fails, users may lose access.

5. Hardware Used in Networks:

   • Routers: Connect different networks and direct data.

   • Switches: Connect devices within a network and intelligently forward data.

Key Terminology

• Bandwidth: The amount of data that can be transmitted in a specific time, measured in bits per second.

• Error Rate: The frequency of errors occurring during data transmission.

• Latency: The delay between data being sent and received, often caused by bottlenecks in the network.

• Transmission Media: The medium through which data travels, affecting speed and reliability (e.g., copper cables, fibre optics, wireless).

Key Ideas

1. Bandwidth:

   • Determines the volume of data that can be sent and received.

   • Higher bandwidth allows for more simultaneous connections and faster data transfer.

2. Number of Users:

   • Too many users on the same network can slow performance due to limited bandwidth.

   • Efficient network design is essential for managing traffic.

3. Transmission Media:

   • Fibre optic cables provide higher bandwidth and less interference than copper cables.

   • Wireless connections are more convenient but have lower bandwidth and reliability compared to wired connections.

4. Error Rate:

   • Errors occur more frequently on unreliable connections, requiring data to be resent.

   • Factors affecting error rates include cable quality, length, and environmental interference.

5. Latency:

   • Caused by slow hardware, inefficient network design, or congestion.

   • Minimising latency improves the user experience, especially for real-time applications like video calls and gaming.

6. 
   

Key Terminology

• Client: A device that makes requests to a server for resources or services.

• Server: A central device that provides services, manages resources, and controls security within a network.

• Client-Server Model: A network structure where servers manage access, security, and resources for connected clients.

• Peer-to-Peer Model: A decentralized network structure where devices (peers) share resources directly without a central server.

Key Ideas

1. Client-Server Networks:

   • The server manages shared resources, including files, internet access, printing, email, and backups.

   • Clients make requests to the server for data or resources.

   • Advantages:

     • Centralized management makes security and updates easier.

     • Simplifies backing up shared data.

     • Updates can be applied to all devices simultaneously.

   • Disadvantages:

     • Expensive to set up and maintain.

     • Requires IT specialists.

     • A single point of failure; if the server crashes, users lose access.

2. Peer-to-Peer Networks:

   • All devices (peers) are equal and share files directly with each other.

   • Peers manage their own backups and security.

   • Devices can act as both clients and servers.

   • Advantages:

     • Simple and inexpensive to set up.

     • No reliance on a central device; no single point of failure.

     • Does not require specialist staff.

   • Disadvantages:

     • Less secure, as each peer handles its own security.

     • More challenging to maintain an organized file system.

     • Reliability depends on the availability of individual peers.

3. Comparison of Models:

   • Client-Server: Best for larger organizations where centralized control and reliability are essential.

   • Peer-to-Peer: Suitable for smaller setups, such as home networks or small businesses, due to its simplicity and lower cost.

Key Terminology

• Network Interface Controller (NIC): Hardware that connects a device to a network and ensures successful communication.

• Wireless Access Point (WAP): Allows wireless devices to connect to a network.

• Switch: Directs data to the correct device within a network.

• Router: Connects different networks and directs data between them.

• Copper Cables (UTP): Wires twisted to reduce interference; used for wired network connections.

• Fibre Optic Cables: Use light to transmit data over long distances with high bandwidth.

Key Ideas

1. Network Interface Controller (NIC):

   • Every device on a network needs an NIC, either integrated or as an add-on.

   • NICs enable devices to connect to wired or wireless networks using a defined set of rules.

2. Wireless Access Points (WAPs):

   • Facilitate wireless connections, eliminating the need for physical cables.

   • Offer convenience but lower bandwidth and security compared to wired connections.

3. Switches:

   • Used in LANs to send data to specific devices by learning which devices are connected.

   • Segments network traffic to improve efficiency.

4. Routers:

   • Connect LANs to Wide Area Networks (WANs) and direct data to its destination using IP addresses.

   • Essential for creating WANs and providing internet access.

5. Transmission Media:

   • Copper Cables (UTP):

     • Affordable and easy to install but susceptible to interference.

     • Twisted pairs reduce signal degradation.

   • Fibre Optic Cables:

     • Transmit data as light, providing higher bandwidth and longer distance coverage.

     • Used as the backbone of the internet due to reliability and speed.

6. Reliability and Security:

   • Wired connections provide more secure and stable connections compared to wireless.

   • Fibre optic cables experience less interference than copper cables, making them ideal for critical infrastructure.

Key Terminology

• IP Address: A unique number that identifies a device on the internet (like a phone number for computers).

• DNS (Domain Name System): A system that helps turn website names (like www.google.com) into IP addresses that computers can understand.

• HTTP (HyperText Transfer Protocol): The system used to transfer web pages from the server to your browser.

• HTTPS (HyperText Transfer Protocol Secure): A secure version of HTTP that keeps your data safe when browsing websites.

• Router: A device that helps direct internet traffic between your device and the server.

• TCP/IP: A set of rules that make sure data can travel across the internet safely and reach the correct place.

Key Ideas

How the Internet Works:

• The internet connects millions of devices around the world. It allows these devices to communicate and share information using special rules called TCP/IP.

Role of DNS:

• DNS acts like a phonebook for the internet. When you type a website name (like www.example.com), DNS finds the correct IP address so your device can connect to that website.

IP Addressing:

• IPv4: A number used to identify a device, like 192.168.1.1.

• IPv6: A newer number format that allows for more devices to connect to the internet.

Protocols:

• HTTP: Used for regular web browsing.

• HTTPS: A safer version of HTTP used for secure browsing (especially for online shopping and banking).

• TCP/IP: Ensures that data is sent and received correctly over the internet.

Advantages and Disadvantages

Advantages of the Internet:

• Global Communication: You can talk to anyone in the world.

• Access to Information: You can find information on almost anything.

• Cloud Services: Store and access files online, without needing a physical device.

Disadvantages of the Internet:

• Security Risks: Hackers and viruses can try to steal information.

• Privacy Issues: Your personal information could be accessed by others.

• Internet Dependence: If the internet goes down, many services and devices stop working.

Key Terminology

• Topology: The physical or logical arrangement of devices in a network.

• Star Topology: All devices connect to a central node, such as a switch or server.

• Mesh Topology: Devices are connected to multiple others, creating multiple pathways for data.

• Central Node: A hub, switch, or server used in star topologies to manage communication.

• Fault Tolerance: The ability of a network to continue functioning when parts fail (common in mesh networks).

• Redundancy: Additional pathways or connections in a network to ensure reliability.

Key Ideas

Star Topology

• How it works:
  Devices communicate via a central node that manages data transmission. Each device is connected directly to the hub.

• Advantages:

  • Easy to set up and manage.

  • Isolates device failures—if one connection fails, other devices remain unaffected.

  • Suitable for smaller networks like home setups or small offices.

• Disadvantages:

  • The central node is a single point of failure—if it goes down, the entire network fails.

  • Requires more cabling in larger networks, increasing costs.

Mesh Topology

• How it works:
  Each device connects to multiple others, creating multiple paths for data. Data can travel through different routes if one fails.

• Advantages:

  • Provides fault tolerance—no single point of failure.

  • Ideal for large, critical networks (e.g., hospitals, data centers) where reliability is key.

  • Excellent for handling high network traffic.

• Disadvantages:

  • High cost and complexity due to the number of connections needed.

  • Difficult to set up and manage for larger networks.

Key Terminology

• Wired Connection: Physical cables, such as Ethernet or fibre optics, used to connect devices to a network.

• Wireless Connection: Uses radio waves (e.g., Wi-Fi) to connect devices without physical cables.

• Ethernet: A common wired connection standard used in local area networks.

• Wi-Fi: A wireless technology that allows devices to connect to a network.

• Frequency Bands: The ranges (e.g., 2.4 GHz and 5 GHz) at which wireless signals are transmitted.

• Interference: Signal disruption caused by overlapping devices, walls, or other obstacles.

Key Ideas

Wired Connections

• How it works:
  Devices connect via physical cables (e.g., Ethernet, fibre optics).

• Advantages:

  • Stable and reliable.

  • Faster speeds and lower latency than wireless.

  • More secure, as it’s harder for attackers to intercept data.

• Disadvantages:

  • Limited mobility—devices must stay near the cable.

  • Can be expensive and difficult to install (especially for large networks).

Wireless Connections

• How it works:
  Devices connect via Wi-Fi, using radio waves and a wireless access point (WAP).

• Advantages:

  • Highly flexible—devices can connect from anywhere within range.

  • Easier and cheaper to set up compared to wired networks.

• Disadvantages:

  • Less secure—data can be intercepted without proper encryption.

  • Signal can be disrupted by walls, interference, or distance.

  • Often slower than wired connections.

Wi-Fi Frequency Bands

• 2.4 GHz:

  • Longer range but slower speeds.

  • More prone to interference (commonly used for household devices).

• 5 GHz:

  • Faster speeds but shorter range.

  • Less interference due to fewer devices using this frequency.

Key Terminology

• Encryption: The process of scrambling data into an unreadable format, which can only be decoded by authorized devices using a specific key.

• Decryption: The process of converting encrypted data back into readable form using the correct key.

• WPA (Wi-Fi Protected Access): A security protocol that improves upon WEP for encrypting wireless networks.

• WPA2: A more secure and widely used encryption standard that replaced WPA.

• WPA3: The latest wireless security protocol with improved security features.

• Public Key Encryption: A type of encryption where different keys are used for encryption and decryption.

• Brute-Force Attack: A method hackers use to break encryption by trying all possible keys.

Key Ideas

What is Encryption?

• Encryption secures data by converting it into a form that unauthorized users cannot read.

• Wireless encryption is especially important because wireless data can be intercepted more easily than wired data.

• Wireless Encryption Protocols ensure that only authorized devices can connect and exchange data securely.

Wireless Encryption Protocols

1. WPA (Wi-Fi Protected Access):

   • Introduced as a replacement for WEP, which had significant security flaws.

   • Includes improved encryption but is now considered outdated and less secure.

2. WPA2 (Wi-Fi Protected Access 2):

   • Uses AES (Advanced Encryption Standard), offering much stronger encryption than WPA.

   • Commonly used in most modern networks.

   • Vulnerable to some specific attacks, such as KRACK (Key Reinstallation Attack) - It’s a way that hackers can break into a Wi-Fi network, even if it’s protected by WPA2 (a common type of Wi-Fi security). Keeping your devices updated closes the door to this attack.

3. WPA3 (Wi-Fi Protected Access 3):

   • Latest standard with enhanced security features.

   • Protects against brute-force attacks by introducing Simultaneous Authentication of Equals (SAE).

   • Includes forward secrecy, which ensures past communications remain secure even if the encryption key is compromised.

Why is Encryption Important?

• Prevents unauthorized access to networks and data.

• Protects sensitive information such as passwords, banking details, and personal communications.

• Ensures data integrity by preventing tampering during transmission.

• Necessary for maintaining privacy, especially on public Wi-Fi networks.

Key Terminology

• IP Address (Internet Protocol Address): A unique identifier for devices on a network used to route data.

• IPv4: The older version of IP addresses, consisting of 32 bits (e.g., 192.168.0.1).

• IPv6: A newer version of IP addresses with 128 bits (e.g., 2001:db8::ff00:42:8329), designed to support more devices.

• MAC Address (Media Access Control Address): A unique, permanent hardware address assigned to a device's network interface.

• DHCP (Dynamic Host Configuration Protocol): A protocol that automatically assigns IP addresses to devices on a network.

• Static IP Address: An IP address manually assigned to a device that does not change.

• Dynamic IP Address: An automatically assigned IP address that may change over time.

Key Ideas

What is an IP Address?

• Used to identify devices on a network and route data to the correct destination.

• Divided into two main types:

  • IPv4:

    • Format: Four numbers separated by dots (e.g., 192.168.1.1).

    • Limited to around 4.3 billion unique addresses.

  • IPv6:

    • Format: Eight groups of hexadecimal numbers separated by colons (e.g., 2001:db8::ff00:42:8329).

    • Vastly larger address space to support modern internet demands.

What is a MAC Address?

• A hardware-based address unique to each device, assigned during manufacturing.

• Used within a local network (LAN) for device communication.

• Written in hexadecimal format (e.g., 00:1A:2B:3C:4D:5E).

• Does not change, unlike IP addresses.

How IP and MAC Addresses Work Together

• IP Address: Used for communication between networks (e.g., sending data across the internet).

• MAC Address: Used within a local network to ensure data is delivered to the correct device.

• Together, they ensure data travels efficiently and securely across networks.

Static vs. Dynamic IP Addresses

• Static IP Address: Manually assigned and does not change, often used for servers or important devices.

• Dynamic IP Address: Automatically assigned by DHCP and can change over time, commonly used for home and business devices.

Key Terminology

• Standard: A set of agreed rules or guidelines that ensure compatibility between hardware and software.

• Open Standards: Freely available standards used globally, such as TCP/IP and HTTP.

• Proprietary Standards: Standards owned by a specific company, such as Apple’s AirPlay.

• Protocol: A set of rules governing how data is transmitted across a network.

• Interoperability: The ability of devices or systems to work together using common standards.

• Encryption: Secures data transmission, commonly used in protocols like HTTPS.

Key Ideas

Standards

1. What are Standards?

   • Standards ensure that devices, software, and systems from different manufacturers can work together.

   • Examples: Ethernet (wired networks), Wi-Fi (wireless networks), and HTTP (web browsing).

2. Open vs. Proprietary Standards:

   • Open Standards: Freely available for anyone to use. They promote compatibility and innovation (e.g., HTML, TCP/IP).

   • Proprietary Standards: Owned by a company, often optimized for their specific systems but can limit compatibility (e.g., DOCX files).

3. Examples of Networking Standards:

   • Ethernet (IEEE 802.3): Standard for wired networks.

   • Wi-Fi (IEEE 802.11): Standard for wireless connections.

   • HTTP/HTTPS: Standards for web browsing.

Protocols

1. What are Protocols?

   • Protocols are rules that define how data is sent, received, and processed across networks.

2. Common Protocols:

   • TCP/IP (Transmission Control Protocol/Internet Protocol):

     • TCP splits data into packets, ensures correct delivery, and reassembles them.

     • IP handles addressing and routing of packets.

   • HTTP/HTTPS (HyperText Transfer Protocol/Secure):

     • HTTP is used for web communication.

     • HTTPS adds encryption for secure browsing.

   • FTP (File Transfer Protocol): Used for transferring files between computers.

   • SMTP (Simple Mail Transfer Protocol): Sends emails between servers.

   • IMAP (Internet Message Access Protocol): Allows remote management of emails stored on a server.

3. The Importance of Protocols:

   • Protocols ensure reliable, efficient, and secure communication between devices.

   • They allow different systems to communicate regardless of manufacturer.

Key Terminology

• Layer: A division of network functionality, with each layer responsible for a specific aspect of data transmission.

• Protocol Stack: A collection of protocols working together, organized into layers.

• TCP/IP Model: A standard model for network communication, consisting of four layers.

• Application Layer: Provides services for user-facing applications, such as web browsers.

• Transport Layer: Splits data into packets and ensures they are delivered correctly.

• Network Layer: Handles addressing and routing of data (e.g., IP addresses).

• Link Layer: Manages physical connections, such as hardware and cables.

Key Ideas

What are Layers?

• Layers divide the process of network communication into manageable parts.

• Each layer has a specific function and communicates only with the layers directly above and below it.

• Example: The TCP/IP model is a commonly used protocol stack with four layers.

The TCP/IP Model

1. Application Layer

   • Provides services for applications such as web browsers and email clients.

   • Examples of protocols:

     • HTTP/HTTPS: Web browsing.

     • SMTP/IMAP: Email communication.

2. Transport Layer

   • Splits data into packets, ensures they are sent correctly, and reassembles them at the destination.

   • Example of protocol:

     • TCP (Transmission Control Protocol).

3. Network Layer

   • Adds source and destination IP addresses to packets and routes them across networks.

   • Example of protocol:

     • IP (Internet Protocol).

4. Link Layer

   • Manages physical connections and handles data transfer between devices on the same network.

   • Includes hardware like NICs and transmission media.

Why Use Layers?

1. Simplification

   • Breaking communication into layers makes network design easier to understand and manage.

2. Interoperability

   • Devices and protocols from different manufacturers can work together using the same layer model.

3. Troubleshooting

   • Layers help isolate and fix network problems by identifying which part of the process is failing.