Y10 - ICT - End of year Examination Revision guide
Benefits of Using a Local Area Network (LAN)
What are the benefits of a LAN?
Users can share peripherals such as printers, which reduces cost and time to access a central device.
Shared access to the internet reduces the need for individual connectivity.
Users can access their files from any computer on the network, allowing for flexible access and hot desking.
Communication can be made easier via email and social networks.
Users can share files and folders easily, such as central databases and spreadsheets.
Servers can be used to provide centralized backups, updates, and security.
Media streaming (movies, music, and gaming) is facilitated.
What are the drawbacks of a LAN?
There is an increased security risk to data.
Malicious software can infiltrate the network and render it unusable.
Servers and switches can provide a central point of failure, resulting in users not being able to complete tasks.
Factors can impact the performance of the network, such as the number of users and data on the network at one time.
Peer-to-Peer & Client-Server Networks
Peer-to-Peer Networks
What is a peer-to-peer network?
A peer is a computer on a network which is equal to all other computers.
Each peer:
Often has its own printer attached.
Will provide access to its own files.
Is responsible for its own backups.
Is responsible for its own security.
Is responsible for carrying out its own backups.
A network with no server providing services is a peer-to-peer network.
Most homes will have a peer-to-peer network model.
Advantages:
Very easy to set up and maintain.
Very cheap to set up because there is no expensive hardware to purchase.
No specialist knowledge or staff are required to run the network.
Disadvantages:
Users will need to manage their own backups.
Users will need to manage their own software updates.
The network can be less secure.
No control of user access rights which reduces security.
No centralized administration means no remote updates.
No centralized backup, so each client has to be backed up separately; individual backup devices need to be used on each device, costing more.
No shared software, meaning more installs.
No shared storage/file access, increasing the need for storage on each device/access from anywhere.
No roaming profiles, meaning users cannot ‘hot-desk’.
Client-Server Networks
What is a client-server network?
A client is a computer on the network; these connect to the server via a switch.
A server is a computer on a network which often has a single purpose, for example:
Managing access to the Internet.
Managing printing.
Providing email services.
Providing backups.
Controlling security.
Servers are often more powerful than the client machines.
Servers are seen as more significant than the client machines and can require specialist hardware and software.
A network which uses a server is called a client-server model.
Most companies, organizations, and schools will use a client-server network model.
Advantages:
Managing backups of the network is easier as it is done from one central point.
Updating and installing new software can be done centrally instead of having to log on to each machine.
Security of files can be managed easily.
Disadvantages:
Servers can be expensive to purchase, setup, and maintain.
A specialist network manager would be required as servers require specialist IT knowledge.
Servers can be a single point of failure, meaning all users would lose access to the network if the server fails.
Types of Digital Communications
Satellite Communication
What is satellite communication?
Satellite communication uses radio waves for wireless communication.
Signals are sent between satellites and ground stations on earth.
Ground stations transmit the radio wave to antennas within or connected to a digital device.
Advantages:
The service is always available.
Disadvantages:
The service can be interrupted by weather conditions.
Signals do not pass through solid objects.
Satellite Television
Digital Video Broadcasting (DVB) is the international standard for broadcasting digital television.
Digital Video Broadcasting-Satellite (DVB-S) is an example of DVB.
A video signal is sent from a broadcaster to a satellite and sent back to earth to an antenna connected to a set-top box or directly to a television.
The set-top box or television decodes the signal to make it watchable.
TV & Radio
What is digital television and radio?
Digital Video Broadcasting Terrestrial (DVB-T) and Digital Audio Broadcasting (DAB) are methods of transmitting video and audio signals from transmitters to an antenna.
Transmitters are based on earth.
Once received by the antenna, signals travel through wires to a television or radio receiver which decodes the signal and converts it into video and/or audio.
Advantages:
Improved video/audio quality.
Access to more channels/stations.
Wired Methods of Communication
There are a number of wired methods of communication, some are designed to transmit a specific type of data and some are universal.
Type Use
High Definition Multimedia Interface (HDMI): High definition video and audio signals
Sony/Phillips Digital Interface Format (S/PDIF): Transmit digital audio streams between devices
Mini-jack: 3.5mm jack commonly used to connect headphones, speakers, and microphones to devices
Ethernet: Networking standard for connecting devices to a local area network (LAN)
Universal Serial Bus (USB): Connecting and powering various devices such as printers, flash drives, keyboards, mice etc.
Wireless Methods of Communication
There are a number of wireless methods of communication, including:
Type Use
Wireless Fidelity (Wi-Fi): A wireless method of connecting devices to a local area network (LAN)
Bluetooth: Allows two devices to connect to each other over very short distances
Infra-red (IR): Transmits tiny amounts of data over very short distances
Near Field Communication (NFC): Use close proximity
RFID (radio frequency identification)
4G and 5G: Provides internet access to mobile devices
Advantages of using a wired method to connect to a smartphone:
Faster/higher bandwidth/lower latency
More stable connection
Less interference (e.g. dropped packets, loss of data)/Not affected by physical obstructions (e.g. walls)
More secure
Password not needed
Advantages of using a wireless method to connect to a smartphone:
Can move around (while transferring data)
Does not have to waste time finding/connecting cables
Cost of cables/cheaper
Health and safety/no trailing wires
Networks
Local Area Networks (LANs)
What is a local area network?
A local area network (LAN) is a network which has a small geographical area (under 1 mile).
All of the hardware is owned by the company/organization/household using it.
LANs will use unshielded twisted pair (UTP) cable, fibre optic cable, or wireless connections (Wi-Fi).
Advantages:
Allows centralized management of updates, backups, and software installations.
Can secure its devices with the use of firewalls, antivirus software, and other security features to prevent unauthorized access.
Allows users on the network to share resources such as printers and other peripherals.
Allows the users of the network to collaborate and share files and folders.
Disadvantages:
If hardware fails, the network may not function properly or even at all.
Networks are more prone to attacks than standalone computers.
Access to data and peripherals can be slow depending on network traffic.
Require maintenance to ensure that software is up to date, upgrades, and backups which can be costly.
Wide Area Networks (WANs)
What is a wide area network?
A wide area network (WAN) is a network which has a large geographical area (over 1 mile).
They are a collection of LANs joined together.
The computers on a WAN are connected via routers.
The hardware used to connect the networks together is not all owned by the company/organization/household using it; for example, telephone lines owned by telecommunication companies.
WANs will use fibre optic cable, telephone lines, and satellite to connect the LANs together.
Personal Area Networks (PANs)
What is a PAN?
A personal area network (PAN) is a network that is used for the transmission of data between devices in close proximity.
A PAN has a very short range (10 meters).
Bluetooth is the most widely used PAN.
Typical examples of devices which make use of a PAN are:
Wireless headphones
Mobile phones
Tablet
Laptop etc.
Tethering
What is tethering?
Tethering is when a host device shares its internet connection with other connected devices.
Commonly used by mobile devices to share its mobile data connection to devices such as laptops and tablets.
Tethering can be enabled or disabled as part of the mobile contract.
Some network providers charge extra to use this feature.
Wireless Communications
Wi-Fi
What is Wi-Fi?
Wireless fidelity (Wi-Fi) is a common standard for wireless networks.
Wi-Fi is common in most homes and offices to connect devices such as laptops, tablets & smartphones.
Using Wi-Fi, devices communicate with a hotspot or a wireless access point (WAP), which can be a standalone device or built into a router or switch.
Wi-Fi may be preferred over Bluetooth when:
High-speed data transfer is required.
Long-range communication is required.
Many devices are needed to be connected at the same time.
Advantages:
Portability - Easy to move around, location is only limited by range
Cost - Less expensive to setup and add new devices
Compatibility - Most devices are manufactured with a built-in Wi-Fi adapter
Disadvantages:
Speed - Slower data transfer than Ethernet
Security - Less secure than Ethernet
Range - Relies on signal strength to the WAP, signals can be obstructed (up to 100m)
Bluetooth
What is Bluetooth?
Bluetooth is another common standard for wireless networks.
Bluetooth is common in most homes and offices to connect devices such as headphones, controllers, keyboards & mice.
Bluetooth is used typically for a direct connection between two devices.
When two devices pair, they both exchange a cryptographic key.
The keys are used to generate a secret shared key which is used to encrypt the data between the two devices and create a Wireless Personal Area Network (WPAN).
Connected devices continuously change their transmitting frequency between 79 different channels to avoid interference and improve the reliability of the connection. This is known as the frequency hopping spread spectrum (FHSS).
Advantages:
Compatibility - Ideal for personal devices and ad-hoc connections
Power - Very low power consumption
Disadvantages:
Speed - Very slow transfer speeds
Security - Data can be intercepted by anyone in range
Range - Short range (30m)
Differences between Bluetooth and Wi-Fi
Maximum number of connections
Bluetooth: 7
Wi-Fi: 30
Transmission frequency
Bluetooth: 2.4Ghz
Wi-Fi: 2.4Ghz, 5Ghz
Maximum range (meters)
Bluetooth: 30 meters
Wi-Fi: 100 meters (depending on obstructions)
Maximum transfer speed (Depending on the standard being used)
Bluetooth: 3 Mbytes/Sec
Wi-Fi: 75 Mbytes/Sec
GPS
What is GPS?
Global Positioning System (GPS) is a satellite system used to track the exact location of an object.
GPS uses orbiting satellites to receive, amplify, and transmit signals.
Radio frequencies are used to communicate between satellites and ground stations.
GPS requires a direct line of sight.
Case Study: Sat nav in a car
The position/location of the car is calculated using GPS software.
Data is transmitted every few seconds.
An algorithm calculates the speed/location of the car.
The map is updated every few seconds.
Advantages:
Wide coverage area
Real-time data transmission
Improved communication in remote locations
Accurate location tracking
Disadvantages:
Expensive setup and maintenance
Signal interference due to weather or obstacles
Limited bandwidth and capacity
Privacy concerns and potential for Surveillance
3G & 4G
What is 3G & 4G?
3G and 4G are references to the 3rd and 4th generation of mobile data networks.
They provide mobile devices with wireless access to the internet.
Each generation has a faster transfer rate and an improved capacity for more users.
3G - 256 Kbps (kilobits per second)
4G - 100+ Mbps (megabits per second)
The current generation (5G) has even faster speeds and lower latency
Infra-red (IR)
What is infra-red?
Infra-red is a wireless communication method used to transfer very small amounts of data to a device in direct line of sight.
Commonly used in remotes to control devices such as:
Televisions
Audio receivers
Home entertainment equipment etc.
Uses light waves which can cause:
Walls or obstacles to block the signal
Sunlight to affect the signal
It is a reliable and cost-effective solution for many short-range wireless communication needs.
NFC
What is NFC?
Near field communication (NFC) is a subset of RFID which allows communication between two devices in very close proximity.
NFC can be either:
Passive - uses energy from the reader
Active - has its own power source
Smartphones use active NFC to allow contactless payments by tapping a smartphone on a reader.
Smartphones can also exchange data using NFC by tapping together (usually back to back).
Advantages:
Convenient
Secure
Very fast
Low power consumption
Disadvantages:
Limited range
Slow data transfer rate (not suitable for transferring large files)
Compatibility
Requirements for Connecting to a Network
Identifying Devices
IP Addresses
What is an IP address?
An IP (Internet Protocol) address is a unique identifier given to devices which communicate over the Internet (WAN).
IP addresses can be allocated by a network administrator or assigned dynamically by a Dynamic Host Configuration Protocol server (DHCP).
IP addresses make it possible to deliver data to the right device.
A device connecting to a network will be given an IP address; if it moves to a different network then the IP address will change.
IPv4
Internet Protocol version 4 is represented as 4 blocks of denary numbers between 0 and 255, separated by full stops.
Each block is one byte (8 bits), each address is 4 bytes (32 bits).
IPv4 provides over 4 billion unique addresses (); however, with over 7 billion people and countless devices per person, a solution was needed.
IPv6
Internet Protocol version 6 is represented as 8 blocks of 4 hexadecimal digits, separated by colons.
Each block is 2 bytes (16 bits), each address is 16 bytes (128 bits).
IPv6 could provide over one billion unique addresses for every person on the planet ().
MAC Addresses
What is a MAC address?
A MAC (Media Access Control) address is a universally unique identifier given to devices which communicate over a local area network (LAN).
MAC addresses are static; they can never change.
MAC addresses make it possible for switches to efficiently forward data to the intended recipient.
Any device that contains a Network Interface Card (NIC) has a MAC address assigned during manufacturing.
A device connecting to a local network already has a MAC address; if it moves to a different network then the MAC address will stay the same.
A MAC address is represented as 12 hexadecimal digits (48 bits), usually grouped in pairs.
The first three pairs are the manufacturer ID number (OUI) and the last three pairs are the serial number of the network interface card (NIC).
There are enough unique MAC addresses for roughly 281 trillion devices.
MAC addresses can be used to:
Restrict or allow access to a network
Identify a device on a network
Track a device
Assign 'static' or 'fixed' IP addresses
Device Name
What is a device name?
A device name is a way for users to describe/name a device so that it is easier to identify on a network.
Device names are not used by devices to communicate as they are not always unique.
Device names are set by users in the devices operating system or from a router.
IP address is dynamic/can change whereas MAC address is static/cannot change.
IP address is used to communicate on a WAN/Internet whereas MAC address is used to communicate on a LAN.
Components of a Network
Cables
What cables are used in a wired network?
A wired network is a network where physical cables are used to join devices together and transmit data.
The most common types of cables in a wired network are:
Ethernet
Fibre optic
What is Ethernet?
Ethernet is a wired networking standard to carry electrical signals between devices on a local area network (LAN).
Ethernet is common in most offices and homes to connect devices such as desktop computers & servers.
Ethernet uses twisted pair cables (CAT5) to allow duplex communication.
What is fibre optic?
Fibre optic is a type of cable that uses light to transmit data on a wide area network (WAN).
Fibre transmits data at a much higher speed and has a much higher bandwidth compared to copper cables.
Fibre optic cable does not suffer from interference which makes them the most secure option to send sensitive data.
Fibre optic cables can cover a long distance without any degradation; they can span cities and countries.
Wireless Access Points
What is a wireless access point (WAP)?
The Wireless Access Point (WAP) allows wireless devices to connect to a local area network (LAN).
The WAP connects to a Switch or Hub via an Ethernet cable.
The WAP range is limited so the use of multiple Wireless Access Points can be used for complete coverage or a home/business.
Router & Gateway
What is a router?
The router is responsible for routing data packets between different networks.
An example of data the router can direct is, sending internet traffic to the right devices in your home.
The router manages and prioritizes data traffic, which can help to keep connections stable.
The router will assign IP addresses to the devices on the network.
The router acts as a gateway.
What is a gateway?
A gateway is a device that bridges the connection between two different types of network.
Gateways translate between different network protocols.
For example, a local area network (LAN) to a wide area network (WAN).
Switch & Boosters
What is a switch?
A Switch allows multiple wired devices to connect to a local area network (LAN).
The Switch is an active device, which means it can inspect network data and route it to the correct device, thus reducing traffic on the network.
A Switch can contain extra Software to allow administration/configuration.
What is a booster?
A booster is a device used to amplify a network signal in order to extend the normal range.
Boosters can be used with both wired and wireless networks.
Wireless access points can be be configured to act as a booster (repeater mode).
Server
What is a server?
A server is a dedicated computer that shares its resources with devices that connect to it.
Devices that connect to a server are known as clients.
Common examples of servers include:
File
Web
Print
Authentication
Application
Server Function
File: Allows access to shared and private resources
Web: Stores the content of websites and processes requests made via HTTP to access them
Print: Manages print jobs and organizes the queue so that individual printers are not overloaded
Authentication: Stores usernames and passwords that can be checked when a user logs in. Authenticated users receive a certificate that allows access to resources
Application: Allows clients access to applications that run directly from the server
A single computer can perform multiple server functions depending on its resources (memory & processor)
A router can perform tasks such as:
Receive packets
Forward/send packets
Maintain a routing table
Identify the most efficient path to the destination/correct IP/correct location
Assign IP addresses to nodes/devices
Connecting to the Internet
Web Browser
What is a web browser?
A web browser is a software application used to locate, retrieve, and display content on the World Wide Web (WWW).
Web browsers are used to display web pages which include images, videos, and other files.
Most web browsers have the following features:
Home page
Ability to bookmark favorites
Keep a history of visited websites
Hyperlinks which allow users to navigate between pages
Internet Service Provider (ISP)
What is an ISP?
An Internet Service Providers (ISP) is a company that provides access to the Internet to users and businesses.
The ISP provides internet access by leasing equipment and telecommunication lines to users that are required to access the internet.
IPS generally charge a subscription fee for access to the internet.
Search Engines
What are Search Engines?
Search engines are tools that locate and display web pages related to the search terms entered by the user.
They are essential for navigating the vast amount of information on the internet.
They index millions of web pages and use algorithms to rank the relevance of each page to the search terms.
How do search engines work?
Search engines work in several stages:
Crawling
Indexing
Ranking
Crawling is when web crawlers scour the internet daily to retrieve new websites
Indexing is how websites are categorized based on the content of their web pages, keywords, and metadata
Ranking is how websites are ranked and listed on search engine pages - this depends on many factors to display the most relevant results
Filter Software
What is filter software?
Filter software uses two lists stored in a database to allow or block access to websites
URLs entered by a user are compared against both lists
The two lists are:
Whitelist - URLs on the whitelist are allowed and the website can be viewed
Blacklist - URLs on the blacklist are not allowed and the website is blocked
URLs that cannot be found on either list are allowed
Filter software is used by schools and parents to protect children from accessing age-inappropriate content
Administrators can add and remove URLs from the lists
Securing Data on a Network
Methods of Securing a Network
Usernames & Passwords
How does a password help?
Passwords are a digital lock to prevent unauthorized access to an account.
Passwords are used to authenticate a user to the network.
They are often stored as an encrypted/ciphered text entry in a database, ensuring that even with unauthorized access to a database, a hacker would not be able to gain access to the individual passwords of users.
Strong passwords and regular password changes are important to maintain security.
Firewalls
What is a firewall?
A firewall is a barrier between a network and the internet.
A firewall prevents unwanted traffic from entering a network by filtering requests to ensure they are legitimate.
It can be both hardware and software and they are often used together to provide stronger security to a network.
Hardware firewalls will protect the whole network and prevent unauthorized traffic.
Software firewalls will protect the individual devices on the network, monitoring the data going to and from each computer.
Encryption
What is encryption?
Encryption is a method of scrambling data so that unauthorized users cannot understand it.
Encryption methods use 'keys', which are specialized programs designed to scramble or unscramble data.
Encryption uses complex mathematical algorithms to scramble the data.
There are two common methods of encryption:
Symmetric
Public key
Symmetric Encryption
The sender uses a key to encrypt the data before transmission.
The receiver uses the same key to decrypt the data.
It's usually faster, making it ideal for encrypting large amounts of data.
The significant downside is the challenge of securely sharing this key between the sender and receiver; if an unauthorized user captures the key, they can decrypt all messages intercepted in transmission.
Public Key Encryption
Public key encryption uses two keys: a public key for encryption and a private key for decryption
Receivers openly share their public key
Senders use this public key to encrypt the data