Networks and the internet Flashcards
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
Client-Server Model:
one device (the client) requests services from another device (the server).
26
Peer-to-Peer Model:
all terminals have equal status and there is no powerful central server, each computer acts as both a client and a server.
27
advantages of Client-Server
- User IDs, passwords and access levels centrally controlled
- Backup is centralised and usually automated
- No access to other users’ files
28
disadvantages of Client-Server
- Can be expensive to set up and to manage
| - Server is single point of failure
29
advantages of peer-to-peer
- cheap to set up and maintain
| - easy sharing
30
disadvantages of peer-to-peer
- no central backing up
- slower performance
- bad security
31
client side processing
Client Processing is where webpages use JavaScript to validate data before it gets sent to the sever for further validation.
32
advantages of client side processing
- Allows for more interactivity by immediately responding to a users' action
- Removes potentially unnecessary processing from the server
33
Disadvantages of client side processing
- 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
Application Programming Interface (API)
a prewritten set of subroutines that provide access to the
| companies data
35
Gateway
A gateway is a node on a network that serves as an entrance to another network.
36
Port
software construct serving as a communication endpoint. Each has a number used by protocols to specify what data is being sent.
37
Circuit Switching
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
Packet Switching
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
Proxies
A proxy ensures there is no direct physical connection between a single user and a remote source.
40
Encryption
A method of transforming data into an unintelligible way so that it cannot be read by unauthorised individuals.
41
Malicous Software
is software that annoys users or damages their data. For example, Worms, Viruses, Trojans, Spyware and ransomware.
42
Worm
A Worm is a standalone program that does not require a user to run it in order for it to spread.
43
Trojan
A Trojan is software that misleads the user of its true intent. Often, they serve to open up back doors in your computer.
44
Phishing
Phishing is using email to manipulate a victim into visiting a fake website and giving away personal information.
45
protecting agaisnt hacking:
- Packet snifferes
| - User access logs
46
Layering
the principle of dividing a complex system into separate slices of functionality
47
Open Systems Interconnection 7 layer model
(7) Application Layer
(6) Presentation Layer
(5) Session Layer
(4) Transport Layer
(3) Networking Layer
(2) Data Link Layer
(1) Physical Layer
48
TCP/IP stack
Application Layer
Transport Layer
Internet layer
Link Layer
49
Transport Layer
(2) Makes and breaks connections with routers
50
Internet Layer
(3) provides links across different network types.
51
Link Layer
(4) Passes data to the physical network
52
application layer
(1) package data and passes it on
53
Domain Name System Server (DNS sever)
System thats stores names for IP addressees on a network
54
Local Area Network (LAN):
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
Wide Area Network (WAN):
a method of connecting remote computers or networks. Typically made up of smaller LANs which have been connected together.
56
relationship between the DNS server and IP addresses
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
advantages of using an external css file
code only needed to be added to one file but the changes are applied to all the pages that use that css file
58
role of JavaScript
the code interactivity into webpages
59
Methods of sending data
- Electronic Data Interchange (EDI)
- Application Programming Interface (API)
- A URL to a file
60
EDI
is the computer-to-computer exchange of business documents in a standard electronic format between business partners.
61
script tag
the tag to include JavaScript code
62
unordered list
63
ordered list
64
```
The individual parts of the list
65
order of main HTML tags
```
html
head
/head
body
/body
/html
```
66
title tag
The text that will appear in the tab heading
67
head text
68
full image tag
img scr="" alt= "" height= "" width=""
69
div
| /div
divides the page into segments allowing for improved styling
70
form tag
defines a form that is used to collect user input
71
how to use a form tag
form
input type="" name=""
/form
72
how to do CSS in HTML
h1 style = "color:blue; ... "
73
background colour CSS property
background-color
74
border colour CSS property
border-color
75
border style CSS property
border-style
76
border width CSS property
border-width
77
font CSS property
font-family
78
font size CSS property
font-size
79
height CSS property
height
80
width CSS property
width
81
changing the contents of an HTML element JavaScript
chosenElement = document.getElementById(“example”);
chosenElement.innerHTML = “Hello World”;
82
writing directly to a document JavaScript
document.write(“Hello World”);
83
Writing an alert box
alert(“Hello World”);
84
CSS identifiers vs classes
and identifier can only be used once on one element but classes can be used on multiple elements
85
styling of elements CSS
h1{
color:blue;
}
86
CSS class
DOT
.infoBox{
background-color: green;
}
87
CSS identifier
HASHTAG
#menu{
background-color: #A2441B;
}
88
Server side processing
used to interact with permanent storage like databases or files. It also renders the pages to the client
89
advantages of server side processing
- doesn't require plugins or browser scripting technology
- more secure
- reduces loading time
90
disadvantage of server side processing
- can be slow
| - pages have to be refreshed often to keep up to date
91
components of a packet
senders address, recievers address, packet contents, sequence number
92
what connects different networks?
routers and gateways
93
SAN
storage area network
94
MAN
metropolitan area network
95
Uses of the internet
communication, information, entertainment, education, financial transactions, controlling devices
96
PDF
portable document format, to display documents exactly as intened
97
JPEG
joint photographic experts group, losy compressed form of graphics storage
98
GIF
graphics interchange format, lossless compressed image file format
99
MPEG
motion picture experts group, a compression standard for audio visual and data files
100
Unicode
character set which displays over a million characters
101
XML
extensible markup language, text based means of describing data.
102
Flash
multimedia platform for creating and displaying graphics (replaced by HTML5)
103
tags
mark out elements on a web page to indicate to a browser how to display or process an element
104
Benefits of a LAN over a WAN
- 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
How to protect a server
- 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
process and purpose of archiving
- copy original data to a new location then delete the original
- To free up storage space while still keeping them available
107
firewall
hardware or software which prevents unauthorized access.
| reads packet data and determines if a threat.
108
characteristics of a LAN (3)
- small geographical area
- owned by organization (privately owned)
- more secure
109
characteristics of a WAN (3)
- covers a large geographical area
- use third party connections (not single ownership)
- less secure
110
advantages of using peer-to-peer networks when downloading off a server
- 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
IP address
unique identifier for a device on a network, its logical so it can be changed.
112
difference between IP and MAC address
IP is logical so can be changed
| MAC is physical so can't be changed
113
why would companies store IP addresses
identify users so the company can track/ monitor the access
114
Difference between an ID and a class
ID is unique and can only be used once but a class can be assigned to many elements
115
What is at the end of all CSS lines
a semicolon ;
116
disadvantage of clientside
- 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
advantage to company of external CSS file
- 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
advantage to user of external CSS file
- the files are smaller so it will take a shorter time to process
119
why is it important to validate server side
javascript code can be amended/ disabled from running therefore the data must be validated server side to check this hasn't happened
120
why is it important to validate client side
the data can be checked before reaching the server giving the user immediate feedback and preventing unnecessary load on the server
121
linking a css file
link rel="stylesheet" href="name.css"
122
linking another webpage
a href="" link text /a
123
additional security as well as passwords
- memorable information
- double passwords/ entry
- smart access card
- biometric access
124
octet
a group of 8 bits used to designate IP addresses
125
benefits of layering
- each layer can be designed and maintained independently
| - easier to maintain
126
what doees layering do
it abstracts the reality to make it simpler
