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Flashcards

Chapter 13- Networks

Hyerin Cho A LEVEL IT A level English 86 cards

Cards in this deck (86)

  1. 1Networka set of computers and devices connected together so they can communicate and share resources
  2. 2Switchconnects devices on a network; has several ports into which network cables are plugged. Each network cable will connect to another device. switch also examines each data packet that it receives and sends the data packet to the desired port where it will be transferred to the next device
  3. 3Packeta set of bits which represent data to be transmitted
  4. 4Hubsimilar to a switch but doesn't examine each data packet that is received; instead simply transmits each data packet to all connected ports; it can also be classes as multi-port repeater
  5. 5Wireless Access Point (WAP)connects Wi-Fi enabled devices to a network; uses radio devices at frequencies of 2.4 GHz or 5 GHz to transmit data. it's usually connected to a switch by a cable, although it's possible in the home to have a combined wireless access point/switch/router.
  6. 6Network interface card (NIC)connects a network cable to a computer or other device. it is connects the motherboard of a device to a network cable
  7. 7Wireless network interface card (WNIC)makes a device 'wireless enabled', meaning that it can connect to a network wirelessly through a WAP
  8. 8Routera switch which can forward data to the correct location in the most efficient manner
  9. 9LANLocal Area Network which connects devices in a single building or area
  10. 10WANWide Area Network which connects devices that are geographically remote
  11. 11Repeateramplifies the signal on a network cable, also another name for an active hub
  12. 12Gatewayconnects two different types of networks
  13. 13Bridgeconnects two LANs
  14. 14Firewallprevents external devices from gaining unauthorized access to a computer system
  15. 15Servera computer on a network which provides resources that can be used by client devices
  16. 16Virussoftware that replicates itself in order to corrupt data
  17. 17Bandwidththe range of frequencies available for a communication method which determines the transmission rate
  18. 18Bit ratethe number of bits that can be transferred per second
  19. 19Streaminga method of displaying sound or video without waiting for the whole file to be downloaded
  20. 20Circuit switchinga single communication path which is opened for the duration of data transmission
  21. 21Packet switchingdata that is broken down into packets that are sent through different routes and reassembled by the recipient
  22. 22Message switchinga method of transmitting data through intelligent node
  23. 23Infrareda communication used by most control devices
  24. 24Fibre optica fine strand of glass that transmits data as light beams
  25. 25Laseran intense beam of light used for transmitting data
  26. 26Bluetootha short range wireless communication standard
  27. 27Biometrica unique physical characteristics of a person that can be used by computers for identification purposes
  28. 28RFIDradio-frequency identification
  29. 29NFCnear field communication
  30. 30Protocola series of rules that ensure data is transferred between devices correctly
  31. 31Malwaremalicious software
  32. 32Cablescopper cables are the most common when connecting devices in a LAN. The most common is unshielded twisted pair (UTP), or Ethernet cable which has no earth wire, meaning it can result in lost data packets at high frequencies
  33. 33Wireless cablesless bandwidth is available and is also susceptible to interference from other wireless devices. This interference can cause lost data packets which reduces the transmission rate.
  34. 34Optical cableAs fiber optics are not susceptible to electrical interference, it is far less likely that data packets will be lost, meaning that the total bandwidth available is considerably higher than with copper cables
  35. 35Communication protocola set of rules that ensure data is transferred between devices correctly
  36. 36Abstraction layersa framework that puts protocols into seven different layers with each layer being an abstraction of communication; physical layer of communication deals with electric & mechanical operations, data link layer deals with data packets, network layer deals with how data is switched, routed and addressed, transport layer ensures data flows correctly, session layer defines protocols between applications during a communication session, presentation layer ensures that data is in a format that can be recognized, application layer deals with specific types of communication application
  37. 37POPPost Office Protocol (POP) defines the rule for email client software to retrieve email. The main method is to connect to an email server, download all messages and store them on the client computer and then delete the messages from the server. It also supports encrypted transmissions of emails
  38. 38IMAPInternet Message Access Protocol (IMAP) is an alternative method for email client software to retrieve emails- its default mode is to leave the email on the server and download a copy to the client instead of downloading the email and then deleting it from the server. so emails can be accessed from remote locations
  39. 39TCP/IPTransmission Control Protocol (TCP) / Internet Protocol (IP) is the basic communication protocol used on the internet and in most LANs and WANs. they consist of two layers
  40. 40TCPdeals with breaking a message down into small data packets that are transmitted and then reassembled at the receiving end
  41. 41IPdeals with the address to ensure that each packet that are transmitted reaches the correct destination. the address will be checked each time a packet reaches a gateway and routed towards the destination
  42. 42FTPFile Transfer Protocol (FTP) is part of the TCP/IP suite and is used to define how computer files should be transferred from one location to another. it allows for users to be authenticated by username and password but also has an option for anonymous connectivity. this sets the rule for how a server should respond using ASCII codes, the data format to use (ASCII, binary) and the mode of data transfer (stream, block or compressed)
  43. 43HTTPHypertext Transfer Protocol (HTTP) is also part of the TCP/IP suite and is used by web browsers to send requests to a web server to view a web page. when the request is received by the web server it sends the web page information back to the web browser
  44. 44SMTP (research)Simple Mail Transfer Protocol (SMTP) is an internet standard for email transmission. user-level client mail applications typically use SMTP only for sending messages to a mail server for relaying. for retrieving messages, IMAP or POP3 are used
  45. 45PPP (research)Point-to-Point Protocol (PPP) is a data link layer (layer 2) communications protocol used to establish a direct connection between two nodes. it connects two routes directly without any host or any other networking device in between and can provide connection authentication, transmission encryption and compression
  46. 46Telnet (research)a protocol used on the internet or LAN to provide a bidirectional interactive text-oriented communication facility using a virtual terminal connection. user data is interspersed in-band with Telnet control information in a 8-bit byte oriented data connection over the TCP
  47. 47UDP (research)User Diagram Protocol (UDP) is one of the core members of the Internet protocol suite. computer applications can send messages, in this case referred to as datagrams, to other hosts on an IP network. prior communications are not required in order to set up communication channels or data paths
  48. 48BitTorrent protocolspecifies how multiple downloads can take place from the same file source concurrently. several clients (peers) download portions of the file. the peers then connect to each other directly to send and receive those portions of the file between themselves. this reduces bandwidth required by the original host of the file and can increase download speeds for clients downloading large files
  49. 49BitTorrent protocol (2)this only works effectively if there are lots of peers downloading the same file, as without lots of peers there are less opportunities to receive portions of the file
  50. 50Malwaremalicious software
  51. 51Spywaremalicious software that records what a user is doing on a computer system- they secretly collect information without the user's consent. they can log user activity including identifying credit card information or usernames and paswords
  52. 52Unauthorized accesscommonly known as hacking, this takes place when a person or device gains access to a computer network without permission. hackers can guess usernames and password
  53. 53Viruscopy themselves automatically to other devices and so the connectivity to a network makes the spread of viruses more likely. viruses are designed to cause damage to data or cause problems to the operation of a computer system
  54. 54Parasitic virusesattach themselves to files on a computer system and are triggered by certain events such as a date and time
  55. 55Macro virusesattach themselves to macros that are part of macro-enabled documents
  56. 56Email virusesarrive as attachments to emails and are triggered by the user opening the document
  57. 57Wormsdo not require files to attach to as they create their own executable files
  58. 58Trojan horsesmalicious programs that disguise themselves as normal software, but if they are run they will actually cause damage. they are often found on websites when a user tries to download some illegal music or films and they end up downloading a Trojan instead
  59. 59Denial of Service Attack (DoS)designed to send more requests to a server than it can deal with. these are easy to launch and difficult to track. they are carried out to cause disruption to an organisation's network or website and often result in users not being able to use the network and customers unable to access the website.
  60. 60Access rightswhen a user logs onto a network, they are given rights to access different parts of that network. these rights are usually related to data but can also be related to services that are available such as accessing WWW
  61. 61The common access rights- create (C): user can create new items of data
    - read (R): users can read existing data
    - update (U): users can make changes to data
    - delete (D): users can delete data
  62. 62Biometric methodsbiometrics are biological characteristics that can be measured. biometric security uses these biological characteristics to authenticate a user's identity and these include retina recognition, facial recognition, fingerprints and voice recognition
  63. 63Firewallscontrols what data can flow into and out of the network. it may be part of a router or it may be software installed on a server that sits between the network and the gateway
  64. 64Backupa copy of the original data which is required if something goes wrong and the original data is either damaged or lost. in the event of a p[problem with the data then the backup copy can be restored.
  65. 65Encryptionthe process of changing the data so that if it is accessed without permission, then it will be unreadable. when data is encrypted, only the intended recipients will be able to decipher (decrypt) it using decipher algorithm.
  66. 66Malware securityAnti-malware software has two main functions; anti-virus and scanning.
  67. 67Anti-virus (anti-spyware)Anti-virus monitor will continually monitor the system for malware. If it detects any unusual behaviour or tell-tale signs of malware, it will prevent that malware from being executed so that no damage can be done to the files or programs.
  68. 68Scanningchecks for malware that may already be on the system- known as scanning the system. if malware is found, user will be given the choice to disinfect the malware, put into quarantine or ignore it. disinfecting is a safe option but any data/program that included the malware will be deleted. quarantine is the safest because it's a safe area where the malware cannot be executed, but the data/program remains isolated until it can be checked more thoroughly.
  69. 69Physical security methodsprotecting the computer equipment, including standard methods that are used to secure other equipment and buildings or specialist physical devices that are designed to protect computer equipment.
  70. 70Physical security methods (security guards)verify every person who enters a building or specific rooms to ensure that they are authorised to gain entry.
  71. 71Physical security methods (main servers)should be protected against electrical surges. this can be done by using extension leads that offer surge protection, but most servers will be protected by uninterruptible power supply (UPS) units which are battery packs that will provide power in the event of a power cut, but will also ensure that the power supply is uniform.
  72. 72Physical security methods (server rooms)should be located in areas that are protected from fires and floods. this should include providing additional fire protection, such as a server room with fireproof doors, carbon dioxide fire extinguishers and putting backup tapes in fireproof safes. the rooms should not be on the ground floor which can be susceptible to floods, and away from water pipes that could potentially burst.
  73. 73Data protection act principlesa data protection act can be used to protect people about whom data is stored. they are known as data subjects. it is not in place to protect general information.
  74. 74In the UK, the Data Protection Act of 1998 includes the following principles which state that information about data subjects must be:- used fairly & lawfully
    - used for limited, specifically stated purposes
    - used in a way that is adequate, relevant & not excessive
    - accurate
    - kept for no longer than is absolutely necessary
    - handled according to people's data protection rights
    - kept safe & secure
    - not transferred outside the European Economic Area without adequate purpose
  75. 75Satellitean object in space that follows an orbital path. in communication, satellite will send microwave signals to a satellite receiving dish on earth.
  76. 76Three different levels or orbit used by satellites:- low earth orbit (LEO) at 500-1500 km from earth requiring 40-80 satellites for global coverage
    - medium earth orbit (MEO) at 5000-12 500 km from earth requiring 8-20 satellites for global coverage
    - geostationary earth orbit (GEO) at fixed points 35 800 km from earth requiring just three satellites for global coverage.
  77. 77Data transfer systemssatellite broadband is an option for people who live in areas that are not covered by wireless broadband connections. they use GEOs that are a long way from earth, so there's a delay (latency) between the sending and receiving of data. thus satellite broadband is not suitable for real-time applications such as internet gaming
  78. 78One of two ways to use satellites for broadbandone-way satellite broadband sends data for download from the internet to the client and uses a public switched telephone network (PSTN) connection for the client to upload data, thus uploading data can be very slow
  79. 79One of two ways to use satellites for broadbandtwo-way satellite broadband allows the client to upload data directly to the satellite as well as to receive data from the satellite, however this requires more expensive equipment that is able to transmit microwaves to space as well as to receive them
  80. 80How television and radio are broadcasted to end usersthey use radio waves, cables or satellites. as radio waves are dependent on the frequencies available, they are limited to the number of channels that can be offered. cable broadcasts are limited to areas where cables are installed. satellite broadcast systems are able to offer far more channels because of being able to broadcast over a larger range of frequencies using microwaves
  81. 81How satellite television broadcasting worksa user needs a set-top box (STB) and a satellite dish. television companies send their television signals from earth to satellites in space. the broadcast channels will be compressed and if necessary encrypted (if subscription is needed). the end-user's satellite dish receives the broadcast from the satellite in geostationary orbit and passes it on by a cable to the STB. the STB will then decrypt any encrypted signals and send them onto a television
  82. 82Benefit of satellite televisionbroadcasting is available in remote areas, which can be useful for people who like to go camping and for those using boats. viewers can also watch their own country's television in neighbouring countries where there is overspill of the broadcast signal
  83. 83Drawbacks to satellite television- initial purchase of equipment can be costly
    - satellite receiving dish may be unsightly in urban areas where several properties all have satellite dishes
    - microwave signals can be lost in severe weather conditions
  84. 84Global Positioning System (GPS)they use satellites to calculate their current location on the earth. they use a process called trilateration using at least 3 satellites to determine the distance between the GPS receiver and each satellite, which enables the exact location to be calculated
  85. 85Applications of GPS- locating emergency vehicles so they can be dispatched to emergencies
    - finding a nearby private hire taxi and calculating taxi fares
    - tracking people, objects and vehicles
    - geotagging photographs
    - satellite navigation (sat nav) systems
    - treasure hunt games such as Geocaching
    - tracking cycling and running routes
  86. 86Drawbacks of GPS- line of sight is required and so finding an exact position can be difficult/impossible when the line of sight to the satellites is blocked
    - signal is dependent upon good atmospheric conditions and so problems can occur in heavy snow or thick cloud

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A level A LEVEL IT Flashcards on Chapter 13- Networks, created by Hyerin Cho on 09/10/2017.
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Hyerin Cho · Oct 2017
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Mar 7, 2018
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