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91 Cards in this Set
- Front
- Back
Internet |
A group of inter connected networks |
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World wide web |
A service that makes use of the internet |
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Wide area network(WAN) |
Any network in which the computers communicate using resources supplied by a “third party carrier” such as BT or sky |
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How do WANs connect to networks |
Cables, phone lines, satellites, radiowaves |
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What is the largest WAN in the world |
The internet |
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IP addresses |
Four 8-bit numbers(0-255) seperated by dots |
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Packet switching |
File broken into packets of 512 bytes and each packet is given a header |
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Headers which can be given to packets during packet switching |
IP address it is going to, sequence number of the packet, number of packets in the whole communication |
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Packets can flow through different routes T/F |
T |
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How is each packet marked |
With the packet number so the packets can be put back together by the receiver |
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Each data packet has a different number of bytes T/F |
F |
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What reorders the packets into the correct order |
The recipient computer |
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What happens to corrupt packets |
They are requested to be resent |
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Nodes |
Points on a network diagram |
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Routers |
Any node that can route packets from one place to another |
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Network interface card |
Built into every networked device |
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How are NICs connected |
Wireless or with a network cable socket |
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MAC address |
Address assigned to each NIC by the manufacturer |
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Why internet doesn’t use MAC instead of an IP address |
IP address can change when devices are on the network |
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What happens when you request a web page |
Each router along the way uses the MAC address of the next router to send the data packet on the next day of its journey |
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Router |
Looks at destination of packets of data and sends them to the network that is closer towards their destination |
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What happens when you request a web page |
Each router along the way uses the MAC address of the next router to send the data packet on the next day of its journey |
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Router |
Looks at destination of packets of data and sends them to the network that is closer towards their destination |
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Switch |
Connects each node in a network know the MAC address of all connected computers and devices. Send packets to the correct computer |
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Hubs |
Send the data to all connected computers |
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Pros of wired networks |
No need to lay cables Easy to connect to new devices Devices can be portable within the range of the access point |
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Pros and cons of wired networks |
No need to lay cables Easy to connect to new devices Devices can be portable within the range of the access point |
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Cons of networks |
Purchasing network hardware is expensive Managing a large network is complicated Viruses may be able to infiltrate the network and infect every computer |
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Topology |
The way in which parts of a system are connected |
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2 types of topology |
Star, bus |
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Star toplogy |
Back (Definition) |
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Bus toplogy |
Back (Definition) |
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Pros of networks |
Computers can share resources such as printers Files can be accessed through any computer in the network Data is easy to back up as it is stored centrally on the server |
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Cons of networks |
Purchasing network hardware is expensive Managing a large network is complicated Viruses may be able to infiltrate the network and infect every computer |
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bus topology |
computers and other devices are all connected to a central coaxialcable |
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star topologydef |
alldevices(nodes)are connectedto a central switch |
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terminators |
placed at each end of the cable absorb signals and prevent them reflecting down the cable |
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star topology pros |
faster data transfer to hub as eachwire ismt shared if one cable fails the other computers are notaffected |
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star topology cons |
required additional hardware suchasthecentral switch andnetwqork cables if the central switch fails |
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bus topology pros |
less cable so cheaper to install the network easier to add more devices as they only need to connect to a central cable |
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Pros of bus toplogies |
Less cables needed to cheaper to install the network Easier to add more devices as they only need to connect to a central cable |
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layer |
group of protocols with a similar function |
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are layers contained or self contaiuned |
self contained |
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4 layers and their names |
application, transport, internet, link |
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what do protocols in the application layer cover |
providing network services to applications |
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what do protocols in the transport layer cover |
setting up communications between 2 devices splitting data into packets checking packets are correctly sent and delivered |
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what do protocols in the internet layer cover
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adding IP addresses to data packets directing packets between devices handling traffic |
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what do protocols in the link layer cover |
passing data over the physical network are responsible for how data is sent as electrical signals over hardware.
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protocol examples in the application layer |
http, https, smtp, imap, ftp |
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protocol examples in the transport layer |
tcp, udp |
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protocol examples in the internet layer |
ip |
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protocol examples in the link layer |
wifi, internet |
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pros of using layers |
1.breaks network communication into manageable pieces 2.as layers are self contained they can be changed without other layers being affected 3.having set rules for each layer forces companies to make compatible, universal hardware and software, so different brands work with each other and always in a similar way |
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http |
used by web browsers to access websites and commiunicate with web servers |
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https |
a more secure version of http which encrypts all information sent and recieved |
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ftp |
used to access, edit and move files between devices on a network |
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imap |
used to retrieve emails from a server |
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smtp |
sends emails transfers emails between servers |
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which 2 protocols control the packaging of data |
tcp and udp |
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tcp |
establishes a connection between the sending and recieving devices and then splits the data into packets |
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udp(user datagram protocol) |
breaks data down into packets without numbering them |
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what does cyber security aim to do |
protect networks, data, programs and computers against damage, cyber attacks and unauthorised access |
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what can cyber attacks target |
individuals, organisations, governements |
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malware |
code designed to cause harm or gain unauthorised access to a compute system often installed without consent |
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typical actions which malware does |
deleting files locking files altering permissions |
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how can malware spread |
viruses worms trojans |
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worms |
like viruses but self replicate without the help of the user |
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viruses |
attach to certain files and harm the device |
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trojans |
malware disguised as legitimate software which are installed without the user knowing what they are |
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pharming |
where a user is directed to a fake version of a website which looks like the real version, when the use inputs their personal information into the website they are handing it over to criminals |
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how pharming can be prevented |
internet browsers using web filters ensuring anti malware software is up to date |
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social engineering |
a way of gaining sensitive information or illegal access by influencing people |
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forms of social engineering |
phishing, shouldering, blagging |
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phishing |
criminals use emails or texts with links to send a victim to a fake website where pharming takes place |
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shouldering/shoulder surfing |
watching or observing a persons activity to get their details |
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blagging/pretexting |
when someone makes up a story or pretends to be someone they are not to persuade the victim to chare information they do not want to share |
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how to reduce risk of shouldering |
being discreet covering keypad when typing |
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reduce risks of physhing |
look at signals of physhing suchc as bad english and bad grammer |
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reduce risks of blagging |
use security measures which cannot be shared such as biometrics |
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penetration testing |
when organisations employ specialists to stimulate potential attacks to their system so they can identify weaknesses |
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2 forms of penetration testing |
white box, black box |
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white box |
stimulates a malicious insider who has knowledge of the current system, the person hacking will be given credentials to help them |
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black box |
stimulates an external hack where the hacker has no assistance from the inside |
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encryption |
when data is translated to code which only someone with the correct key can access |
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anti malware software |
designed to prevent malware from damaging a network |
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firewalls |
examine all data when entering or leaving a network and identify potential threats |
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automatic software updates |
used to patch security holes in software |
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user access levels |
controls which pats of the network different groups of users can access |
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MAC address filtering |
way to ensure only the people on a network are trusted users by checking the MAC address of every device before letting them join the network |
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biometric measures |
use scanners to identify the correct user |
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CAPTCHA |
completely automated turing test to tell computers and humans apart prevents computers from logging into accounts if not under human control |