Networks and the internet Flashcards Preview

A-Level Computer Science OCR > Networks and the internet > Flashcards

Flashcards in Networks and the internet Deck (126)
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1
Q

Network

A

an interconnected set of devices

2
Q

Physical network topology

A

The actual architecture of a network i.e. how its laid out

3
Q

Positives of Networks

A
  • allows sharing of data
  • allows collaberative working
  • good for communication
  • allows sharing of resources e.g. printers, storage and scanners
  • easy to backup to a central point
4
Q

Drawbacks of networks

A
  • The user can become dependent on the network (If the network stops operating then it may not be possible to access various resources)
  • Efficiency of a network can be very dependent on a network manager
  • It is difficult to make a network of computer secure for hackers and outside threats
  • As traffic increases on a network the performance can degrade
5
Q

Protocol

A

A protocol is a set of rules relating to the communication between devices.

6
Q

TCP

A

Transmission Control Protocol – used with IP to ensure error free transmission and package switching

7
Q

IP

A

Internet Protocol – used to transfer all packets across the internet between routers

8
Q

NIC

A

receive and send electrical signals in a network.

9
Q

Router

A

devices which are used to connect networks. they receive data packets from one network and based on the address on the packet forward them of

10
Q

Switches

A

devices used to connect devices on a network, they use the physical hardware MAC address to send data on to the required destination node.

11
Q

MAC Address

A

identifier that is permanently added to a device by the manufacturer

12
Q

Hubs

A

connects nodes together by broadcasting a signal to all possible destinations. The correct destination will accept the signal

13
Q

WAP (wireless access point)

A

use wireless to connect a node to a WiFi network avoiding the need for lots of physical caballing

14
Q

Transmission media

A

the wires that connect a network

15
Q

Coacial Copper Cables

A

older, slower and cheaper

16
Q

Fibre Optic Cables

A

newer, faster and high-capacity

17
Q

Bus Topology

A

an arrangement where nodes are connected to a central communication channel. Each end of the backbone is connected to a terminator. Each node is passive and data is sent in one direction at a time only

18
Q

Bus topology advantages

A

Inexpensive to set up
Devices can easily be added
Good for small networks

19
Q

Bus Topology Disadvantages

A

Main cable is a single point of failure
Limited cable length
Performance degrades with heavy use
Poor security

20
Q

Star Topology

A

an arrangement where a central node or hub provides a common connection point for all other nodes.

21
Q

Star Topology advantages

A

Easy to isolate problems
Good performance
More secure is a switch is used a data is sent only to the recipient

22
Q

Star topology disadvantages

A

Can be expensive to set up because of the length of cable required
Central device is a point of failure

23
Q

Ring topology

A

an arrangement where on node is connect to two others to form and ring.

24
Q

Mesh Topology

A

an arrangement where ever node is connected to every other node.

25
Q

Client-Server Model:

A

one device (the client) requests services from another device (the server).

26
Q

Peer-to-Peer Model:

A

all terminals have equal status and there is no powerful central server, each computer acts as both a client and a server.

27
Q

advantages of Client-Server

A
  • User IDs, passwords and access levels centrally controlled
  • Backup is centralised and usually automated
  • No access to other users’ files
28
Q

disadvantages of Client-Server

A
  • Can be expensive to set up and to manage

- Server is single point of failure

29
Q

advantages of peer-to-peer

A
  • cheap to set up and maintain

- easy sharing

30
Q

disadvantages of peer-to-peer

A
  • no central backing up
  • slower performance
  • bad security
31
Q

client side processing

A

Client Processing is where webpages use JavaScript to validate data before it gets sent to the sever for further validation.

32
Q

advantages of client side processing

A
  • Allows for more interactivity by immediately responding to a users’ action
  • Removes potentially unnecessary processing from the server
33
Q

Disadvantages of client side processing

A
  • Not all browsers support all script

- Because the scripts are processed by the client, they are dependent on the performance of the clients’ machine

34
Q

Application Programming Interface (API)

A

a prewritten set of subroutines that provide access to the

companies data

35
Q

Gateway

A

A gateway is a node on a network that serves as an entrance to another network.

36
Q

Port

A

software construct serving as a communication endpoint. Each has a number used by protocols to specify what data is being sent.

37
Q

Circuit Switching

A

Circuit Switching: a complete circuit or route between two nodes is established before transmission begins. Once the rout is established all data follows this route until transmission is complete.

38
Q

Packet Switching

A

the data to be transmitted is broke up into individual packets at the source computer. each packet is labelled with an address and sequence number. The packet is then forwarded onto the network and follows its own individual route. Depending on network traffic each packet will take different routes at different times to reach their destination where is is then reassembled.

39
Q

Proxies

A

A proxy ensures there is no direct physical connection between a single user and a remote source.

40
Q

Encryption

A

A method of transforming data into an unintelligible way so that it cannot be read by unauthorised individuals.

41
Q

Malicous Software

A

is software that annoys users or damages their data. For example, Worms, Viruses, Trojans, Spyware and ransomware.

42
Q

Worm

A

A Worm is a standalone program that does not require a user to run it in order for it to spread.

43
Q

Trojan

A

A Trojan is software that misleads the user of its true intent. Often, they serve to open up back doors in your computer.

44
Q

Phishing

A

Phishing is using email to manipulate a victim into visiting a fake website and giving away personal information.

45
Q

protecting agaisnt hacking:

A
  • Packet snifferes

- User access logs

46
Q

Layering

A

the principle of dividing a complex system into separate slices of functionality

47
Q

Open Systems Interconnection 7 layer model

A

(7) Application Layer
(6) Presentation Layer
(5) Session Layer
(4) Transport Layer
(3) Networking Layer
(2) Data Link Layer
(1) Physical Layer

48
Q

TCP/IP stack

A

Application Layer
Transport Layer
Internet layer
Link Layer

49
Q

Transport Layer

A

(2) Makes and breaks connections with routers

50
Q

Internet Layer

A

(3) provides links across different network types.

51
Q

Link Layer

A

(4) Passes data to the physical network

52
Q

application layer

A

(1) package data and passes it on

53
Q

Domain Name System Server (DNS sever)

A

System thats stores names for IP addressees on a network

54
Q

Local Area Network (LAN):

A

method of connecting computers together in a small geographical area. All the hardware and infrastructure is owned by the business/ organisation that uses it.

55
Q

Wide Area Network (WAN):

A

a method of connecting remote computers or networks. Typically made up of smaller LANs which have been connected together.

56
Q

relationship between the DNS server and IP addresses

A

a registered domain name is held on the DNS server. The corresponding IP address to a searched domain name is loaded on the users computer.

57
Q

advantages of using an external css file

A

code only needed to be added to one file but the changes are applied to all the pages that use that css file

58
Q

role of JavaScript

A

the code interactivity into webpages

59
Q

Methods of sending data

A
  • Electronic Data Interchange (EDI)
  • Application Programming Interface (API)
  • A URL to a file
60
Q

EDI

A

is the computer-to-computer exchange of business documents in a standard electronic format between business partners.

61
Q

script tag

A

the tag to include JavaScript code

62
Q

<ul></ul>

A

unordered list

63
Q

<ol></ol>

A

ordered list

64
Q

<li>
</li>

A
The individual parts of the list
<ol>
<li>
</li><li>
</li><li>
</li>
</ol>
65
Q

order of main HTML tags

A
html
head
/head
body
/body
/html
66
Q

title tag

A

The text that will appear in the tab heading

67
Q

<h1></h1>

<h2></h2>

<h3></h3>

A

head text

68
Q

full image tag

A

img scr=”” alt= “” height= “” width=””

69
Q

div

/div

A

divides the page into segments allowing for improved styling

70
Q

form tag

A

defines a form that is used to collect user input

71
Q

how to use a form tag

A

form
input type=”” name=””
/form

72
Q

how to do CSS in HTML

A

h1 style = “color:blue; … “

73
Q

background colour CSS property

A

background-color

74
Q

border colour CSS property

A

border-color

75
Q

border style CSS property

A

border-style

76
Q

border width CSS property

A

border-width

77
Q

font CSS property

A

font-family

78
Q

font size CSS property

A

font-size

79
Q

height CSS property

A

height

80
Q

width CSS property

A

width

81
Q

changing the contents of an HTML element JavaScript

A

chosenElement = document.getElementById(“example”);

chosenElement.innerHTML = “Hello World”;

82
Q

writing directly to a document JavaScript

A

document.write(“Hello World”);

83
Q

Writing an alert box

A

alert(“Hello World”);

84
Q

CSS identifiers vs classes

A

and identifier can only be used once on one element but classes can be used on multiple elements

85
Q

styling of elements CSS

A

h1{
color:blue;
}

86
Q

CSS class

A

DOT
.infoBox{
background-color: green;
}

87
Q

CSS identifier

A

HASHTAG
#menu{
background-color: #A2441B;
}

88
Q

Server side processing

A

used to interact with permanent storage like databases or files. It also renders the pages to the client

89
Q

advantages of server side processing

A
  • doesn’t require plugins or browser scripting technology
  • more secure
  • reduces loading time
90
Q

disadvantage of server side processing

A
  • can be slow

- pages have to be refreshed often to keep up to date

91
Q

components of a packet

A

senders address, recievers address, packet contents, sequence number

92
Q

what connects different networks?

A

routers and gateways

93
Q

SAN

A

storage area network

94
Q

MAN

A

metropolitan area network

95
Q

Uses of the internet

A

communication, information, entertainment, education, financial transactions, controlling devices

96
Q

PDF

A

portable document format, to display documents exactly as intened

97
Q

JPEG

A

joint photographic experts group, losy compressed form of graphics storage

98
Q

GIF

A

graphics interchange format, lossless compressed image file format

99
Q

MPEG

A

motion picture experts group, a compression standard for audio visual and data files

100
Q

Unicode

A

character set which displays over a million characters

101
Q

XML

A

extensible markup language, text based means of describing data.

102
Q

Flash

A

multimedia platform for creating and displaying graphics (replaced by HTML5)

103
Q

tags

A

mark out elements on a web page to indicate to a browser how to display or process an element

104
Q

Benefits of a LAN over a WAN

A
  • Can share hardware/software
  • Easy to maintain all computers
  • Staff can work off any computer (meaning no need for each member to have their own computer).
  • Easy for staff to share data.
  • Central backup
105
Q

How to protect a server

A
  • Encrypt the information
  • Set up user access controls
  • Set up a firewall
  • physical security measures e.g. locks in the server room
  • keep logs of whose accessed the data
106
Q

process and purpose of archiving

A
  • copy original data to a new location then delete the original
  • To free up storage space while still keeping them available
107
Q

firewall

A

hardware or software which prevents unauthorized access.

reads packet data and determines if a threat.

108
Q

characteristics of a LAN (3)

A
  • small geographical area
  • owned by organization (privately owned)
  • more secure
109
Q

characteristics of a WAN (3)

A
  • covers a large geographical area
  • use third party connections (not single ownership)
  • less secure
110
Q

advantages of using peer-to-peer networks when downloading off a server

A
  • once its been downloaded there isn’t reliance on the server and can be seen from all devices on the network
  • company doesn’t have to invest in hardware
  • more fault tolerant
  • frees up bandwidth
111
Q

IP address

A

unique identifier for a device on a network, its logical so it can be changed.

112
Q

difference between IP and MAC address

A

IP is logical so can be changed

MAC is physical so can’t be changed

113
Q

why would companies store IP addresses

A

identify users so the company can track/ monitor the access

114
Q

Difference between an ID and a class

A

ID is unique and can only be used once but a class can be assigned to many elements

115
Q

What is at the end of all CSS lines

A

a semicolon ;

116
Q

disadvantage of clientside

A
  • the code may fetch the wrong data from the computer e.g. wrong time
  • clientside can be edited by the user (they can remove validation)
  • other people can view the code and copy it
  • some browsers disable JavaScript to run
117
Q

advantage to company of external CSS file

A
  • saves time/money
  • the file will be easier to read when checking for bugs
  • easy to differentiate between content and formatting
  • consistent throughout whole site
  • can be used for different devices formatting
118
Q

advantage to user of external CSS file

A
  • the files are smaller so it will take a shorter time to process
119
Q

why is it important to validate server side

A

javascript code can be amended/ disabled from running therefore the data must be validated server side to check this hasn’t happened

120
Q

why is it important to validate client side

A

the data can be checked before reaching the server giving the user immediate feedback and preventing unnecessary load on the server

121
Q

linking a css file

A

link rel=”stylesheet” href=”name.css”

122
Q

linking another webpage

A

a href=”” link text /a

123
Q

additional security as well as passwords

A
  • memorable information
  • double passwords/ entry
  • smart access card
  • biometric access
124
Q

octet

A

a group of 8 bits used to designate IP addresses

125
Q

benefits of layering

A
  • each layer can be designed and maintained independently

- easier to maintain

126
Q

what doees layering do

A

it abstracts the reality to make it simpler