1
Q
What is satellite communication?
A
- 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 antenna within or connected to a digital devices
2
Q
What are the advantages of satellite communication?
A
The advantage of satellite communication is that the service is always available
3
Q
What are the disadvantages if satellite communication?
A
The disadvantages of satellite communication is that the service can be interrupted by weather conditions and signals do not pass through solid objects
4
Q
What is satellite television?
A
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
5
Q
What is a digital television and radio?
A
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
6
Q
What is the advantage of digital television and radio?
A
- Improved video/audio quality
- Access to more channels/stations
7
Q
What are some examples of wired methods of communication?
A
- high definition multi media interface
- mini-jack
- ethernet
- universal serial bus
8
Q
What is the use of High Definition Multimedia Interface (HDMI)?
A
High definition video and audio signals
9
Q
What is the use of Sony/Phillips Digital Interface Format (S/PDIF)?
A
Transmit digital audio streams between devices
10
Q
What is the use of Mini-jack?
A
3.5mm jack commonly used to connect headphones, speakers and microphones to devices
11
Q
What is the use of Ethernet?
A
Networking standard for connecting devices to a local area network (LAN)
12
Q
What is the use of Universal Serial Bus (USB)?
A
Connecting and powering various devices such as printers, flash drives, keyboards, mice etc.
13
Q
What are some examples of wireless methods of communication?
A
Wireless fidelity (WIFI), Bluetooth, Infra-red (IR)
14
Q
What is the use of Wireless Fidelity (Wi-Fi)?
A
A wireless method of connecting devices to a local area network (LAN)
15
Q
What is the use of Infra-red (IR)?
A
Transmits tiny amounts of data over very short distances
15
Q
What is the use of Bluetooth?
A
Allows two devices to connect to each other over very short distances
16
Q
What is the use of Near Field Communication (NFC)?
A
Use close proximity RFID (radio frequency identification)
17
Q
What is the use of 4G and 5G?
A
Provides internet access to mobile devices
18
Q
What is a local area network (LAN)?
A
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/organisation/household using it
LANs will use unshielded twisted pair (UTP) cable, fibre optic cable or wireless connections (Wi-Fi)
19
Q
What are the advantages of LANs?
A
- Allows centralised management of updates, backups and software installations
- Can secure its devices with the use of firewalls, antivirus software and other security features to prevent unauthorised 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
20
Q
What are the disadvantages of LANs?
A
- 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
21
Q
What is wide area network?
A
A wide area network (LAN) 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/organisation/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
22
Q
What is a PAN?
A
A personal area network (PAN) is a network that is used for transmission of data between devices in close proximity
A PAN has a very short range (10 metres)
Bluetooth is the most widely used PAN
23
Q
What are some typical examples of devices which make use of a PAN are
A
Wireless headphones
Mobile phones
Tablet
Laptop etc.
24
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
25
What is WIFI?
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 & smart phones
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
26
When would WIFI be preferred over Bluetooth?
High speed data transfer is required
Long range communication is required
Many devices are needed to be connected at the same time
27
What are the advantages of WIFI?
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
28
What are the disadvantages of WIFI?
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)
29
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)
30
What are the advantages of Bluetooth?
Compatibility - Ideal for personal devices and ad-hoc connections
Power - Very low power consumption
31
What are the disadvantages of Bluetooth?
Speed - Very slow transfer speeds
Security - Data can be intercepted by anyone in range
Range - Short range (30m)
32
What are the differences between Bluetooth and Wifi?
Bluetooth: 7 connections, 30 metres maximum range, 3 Mbytes maximum transfer speed
WIFI: 30 connections, 100 metres maximum range, 75 Mbytes maximum transfer speed
33
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
34
What are the advantages of GPS?
Wide coverage area
Real-time data transmission
Improved communication in remote locations
Accurate location tracking
35
What are the disadvantages of GPS?
Expensive setup and maintenance
Signal interference due to weather or obstacles
Limited bandwidth and capacity
Privacy concerns and potential for Surveillance
36
What is 3G and 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
37
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
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
38
When is Infra-red commonly used?
Televisions
Audio receivers
Home entertainment equipment etc.
39
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 it's 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)
40
What are the advantages of NFC?
Convenient
Secure
Very fast
Low power consumption
41
What are the disadvantages of NFC?
Limited range
Slow data transfer rate (not suitable for transferring large files)
Compatibility
42
What is bandwidth?
Bandwidth is the amount of data that can be carried by a connection in one second
Measured in bits per second (bit rate)
A smaller bandwidth means that less data can be sent and the network can slow down, potentially to the point of becoming unusable
43
How does bandwidth have an impact on user experience?
A higher bandwidth means more data can be sent and received in one second
Higher bandwidth can improve:
Upload and download speeds
Online gaming
Streaming high definition video
To stream content, enough data to play a few seconds is downloaded and stored in a temporary area of memory called a buffer
As the contents of the buffer are played, more data is downloaded at the same time to keep the buffer full
If the buffer ever becomes empty playback will pause
To stream successfully, data must be downloaded to the buffer at a faster rate than it is being emptied
44
What is latency?
Latency is the delay between data being sent and received
If there is a big delay between the two, more data will be on the network causing collisions
This can lead to even more packets of data being sent as the error rate will increase
45
How does latency impact on user experience?
Playing games online smoothly, requires a high bandwidth
A high latency can cause lag and the game will not respond as quickly as a users commands
This can cause big issues when users are playing fast paced games or playing against other users with a lower latency (have an advantage due to quicker response times)
Streaming sport content with a high latency can cause micro-stutters and ruin a users watching experience
46
What else can affect the speed & volume of data transfer?
interference, transfer method, blockages, distance
47
What is meant by interference?
Devices that emit electromagnetic signals such as microwaves and fridges can disrupt wireless signals
48
What is meant by transfer method?
Wired connections can carry more frequencies, meaning a higher bandwidth compared to wireless connections
49
What is meant by blockages?
Walls and furniture can block wireless signals, lowering the bandwidth available
50
What is meant by distance?
The strength of a wired and wireless signals reduces as data has to travel further
51
What are the advantages and disadvantages of wired communication?
speed- faster data transfer
portability- location is limited by physical cable
security- better physical security
range- less affected by interference
safety- cable can be a trip hazard
cost- cables and cheap, more devices mean more cables needed
52
What are the advantages and disadvantages of wireless communication?
speed- slower than wired
portability- location only limited by range
security- less secure
range- affected by interferences
safety- none
cost- no cables required
53
What do Internet Service Providers (ISP) provide?
Provide access to high speed internet (broadband)
ISPs use fibre optic or copper cable to create a wide area network (WAN)
54
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
- does not suffer from interference which makes them the most secure option to send sensitive data
- can cover a long distance without any degradation, they can span cities and countries
55
What is a copper cable?
- Copper is a type of cable originally used in telecommunication to transmit voice signals, forming the traditional landline phone network
The ability to use copper to deliver network traffic on a wide area network (WAN) made the internet possible
- degrade over time which limits their range compared to fibre optic
- suffers from interference which can disrupt data quality
- transmits data at a much slower rate, and has a much lower bandwidth compared to fibre optic
56
Exam question: Describe how high latency can affect the experience of making a video call from a smartphone?
It increases the time it takes for data to be transferred between devices [1] meaning his voice/video is out of sync / lagging / delayed [1]
57
What is an IP address?
- An IP (Internet Protocol) address is a unique identifier given to devices which communicate over the Internet (WAN)
- can be allocated by a network administrator or assigned dynamically by a Dynamic Host Configuration Protocol server (DHCP)
-the 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
58
What is 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)
- provides over 4 billion unique addresses (232), however, with over 7 billion people and countless devices per person, a solution was needed
59
What is 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 (2128)
60
What is a MAC address?
- Media access control address
- universally unique identifier given to devices which communicate over a local area network (LAN)
- static (can never change)
- 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
- 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)
- 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
61
What can 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
62
What is a device name?
- way for users to describe/name a device so that it is easier to identify on a network
- are not used by devices to communicate as they are not always unique
- set by users in the devices operating system or from a router
63
Exam question:
Computers in a network can be identified using both IP addresses and MAC addresses.
Describe two differences between IP addresses and MAC addresses
Answer
IP address is dynamic/can change // MAC address is static/cannot change [1]
IP address is used to communicate on a WAN/Internet // MAC address is used to communicate on a LAN [1]
64
What is a wired network?
- a network where physical cables are used to join devices together and transmit data
65
What are the two most common types of cables in a wired network?
- ethernet
- fibre optic
66
What is ethernet?
- ethernet is a wired networking standard to carry electrical signals between devices on a local area network (LAN)
- common use in most offices and homes to connect devices like desktop computers and servers
- it uses twisted pair cables to allow duplex communication
67
What is a fibre optic?
- type of cable using light to transmit data on a wide area network (WAN)
- transmits data at much higher speed, has a higher bandwidth compared to copper cables
- does not suffer from interference, makes them more secure to send sensitive data
- cover long distances
68
What is a wireless access point (WAP)?
- wireless access point allows wireless devices to connect to a local area network
- WAP connects to a switch or hub via an Ethernet cable
- WAP range is limited so the use of multiple wireless access points can be used for complete coverage or a home/business
69
What is a router?
- router is responsible for routing data packets between different networks
- example of data the router can direct: sending internet traffic to the right devices in your home
- manages and prioritises data traffic, which keeps connection stable
- router can assign IP addresses to the devices on the network
- acts as a gateway
70
What is a gateway?
- device that bridges the connection between two different types of network
- gateways translate between different network protocols
for example a local area network to a wide area network.
71
What is a switch?
- switch allows multiple wired devices to connect to a local area network (LAN)
- switch is an active device, it can inspect network data and route it to the correct device, this reduces the traffic on the network
- can contain extra software to allow administration/configuration
72
What is a booster?
- a device used to amplify a network signal in order to extend the normal range
- used with both wired and wireless networks
73
What is a server?
- dedicated computer that shares its resources with devices that connect to it
- devices that connect to a server are known as clients
74
What are some examples of servers?
file, web, print, authentication, application
75
What is the function of a file?
- allows access to shared and private resources
76
What is the function of a web?
- stores the content of a website and processes requests made via the HTTP to access them
77
What is the function of print?
- manages print jobs and organises the queue so that individual printers are not overloaded
78
What is the function of authentication?
- stores usernames and passwords that can be checked when a user logs in
- users receive a certificate that allows access to resources
79
What is the function of application?
- allows clients access to applications that run directly from the server
80
What is a web browser?
- a software application used to locate, retrieve and display content on the world wide web
- used to display web pages including images, videos and other files
81
What are the features of web browsers?
- home page
- ability to bookmark favourites
- keep a history and visited websites
- hyperlinks
82
What is an Internet Service Provider (ISP)?
- a company that provides access to the internet to users and businesses
- ISP provides internet access by leasing equipment and telecommunication lines to users that are required to access the internet
83
What are search engines?
- tools that locate and display web pages related to the search terms entered by the user
- essential for navigating vast amount of information on the internet
84
What are the three stages of search engines?
crawling: when web crawlers scour the internet daily to retrieve new websites
indexing: how websites are categorised based on the content of their web pages, keywords and meta data
Ranking: how websites are ranked and listed on search engine pages
85
What is filter software?
- use two lists stored in a database to allow or block access to websites
- URLS entered by a user are compared against both lists
- used by schools and parents
two lists:
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
86
What are the benefits of a LAN?
- Users can share peripherals such as printers
- Shared access to the internet
- Users can access their files from any computer on the network
- 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 centralised backups, updates and security
- Media streaming (movies, music and gaming)
87
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 using their computer
- Factors can impact the performance of the network such as the number of users and data on the network at one time
88
What is a peer-to-peer network?
- A peer is a computer on a network which is equal to all other computers
Each peer on the network has:
- their own printer attached
- provide access to their own files
- responsible for their own backups
- responsible for their own security
- responsible for carrying out their 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
89
What are the advantages of a peer to peer network?
- 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
90
What are the disadvantages?
- Users will need to manage their own backups
- Users will need to manage their own software updates
- The network can be less secure
91
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, organisations and schools will use a client-server network model
92
What are the advantages of a client-server network?
- 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
93
What are the disadvantages of a client-server network?
- Servers can be expensive to purchase, setup and maintain
- specialist network manager would be required as servers require specialist IT knowledge
- can be a single point of failure, meaning all users would lose access to the network if the server fails
94
How do passwords help when securing a network?
- a digital lock to prevent unauthorised access to an account and are used to authenticate a user to the network
- stored as an encrypted/ciphered text entry in a database, ensuring that even with unauthorised 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
95
What is a firewall?
- barrier between a network and the internet
- prevents unwanted traffic from entering a network by filtering requests to ensure they are legitimate
96
What are the two types of firewalls?
Hardware firewalls- will protect the whole network and prevent unauthorised traffic
Software firewalls- will protect the individual devices on the network, monitoring the data going to and from each computer
97
What is encryption?
- method of scrambling data so that unauthorised users cannot understand it
- Encryption methods use 'keys', which are specialised programs designed to scramble or unscramble data
- uses complex mathematical algorithms to scramble the data
There are two common methods of encryption:
Symmetric
Public key
98
What is symmetric encryption?
- sender uses a key to encrypt the data before transmission
- 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 unauthorised user captures the key, they can decrypt all messages intercepted in transmission
99
What is public key encryption?
Public key encryption uses two keys:
- a public key for encryption
- a private key for decryption
(Receivers openly share their public key)
- Senders use this public key to encrypt the data
The receiver's private key is the only key that can decrypt the data and is kept locally on their side
The public and private keys are created at the same time and are designed to work together in this way
It is typically slower than symmetric encryption
It is generally used for more secure and smaller data transactions, e.g. passwords, bank details
100
What is WEP?
- method of encrypting data being transmitted on a wireless network
- each device on the network uses the same key to encrypt and decrypt data
- less secure encryption method due to all devices on the network sharing the same key
Eavesdropping software (packet sniffers) can be used to intercept data packets and identify the key
101
What is WPA?
- Wi-fi Protected Access (WPA)
- a more secure method of encrypting data being transmitted on a wireless network
- Each device connected to the network receives a different key
- New keys are used for every packet transmitted on the network
102
What is VPN?
- VPN allows users to remotely connect to private local area networks (LANs)
- All data sent and received using a VPN is encrypted
103
What are the common uses of virtual private network?
- Remotely accessing a companies network (working from home)
- Making secure payments
- Hiding web activities
- By passing geolocation rights management or online censorship
104
What are file access rights?
File access rights can be set to determine different levels of access to specific files/folders
105
What are some examples of file permissions?
Read - can read the contents of a file only
Write - can make changes to file contents and/or create new files
Delete - can delete files
Execute - can run applications/launch software
106
What is a transaction log?
- a secure file on a network that keeps a record of every action performed by devices on a network
- don't directly protect a network, they help administrators monitor any identify any unusual activity
Backups are another indirect method of protecting a network
Keeping copies of data in a secure place on the network in the event of a data breach/loss
107
What do transaction logs include?
- Device & data access
- Timestamps
- User IDs
- Successful/failed login attempts
108
Exam question: Describe one method that could be used to secure payment data transferred between a server and other computers
Encryption [1] encodes/scrambles data / makes data unreadable [1] using a key [1]
ICT THEORY
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