cs networks Flashcards
1
Q
what is a network
A
name given to two or more computers connected together with the ability to transmit data between each other.
2
Q
2 main types of networks
A
local area networks (LAN)
wide area networks (WAN)
3
Q
what is a LAN
A
any network that covers a small geographical area or a single site (School)
4
Q
note about hardware in LAN
A
tends to be owned and controlled by the organisation using it
5
Q
how are LAN connected
A
- UTP cable
- Fibre optic
-WI-FI
6
Q
name of the largest public network
A
the internet
7
Q
What is WAN
A
the name given to a network which covers a large geographical area
example: Large corporations with offices in multiple locations will often have a WAN allowing them to communicate between different sites.
8
Q
how are WANs formed
A
when multiple LANs are physically located in different areas and are connected
9
Q
how are WANs connected
A
telephone lines
fibre optic lines
satellite links
10
Q
2 types of network topology
A
physical
logical
11
Q
what is a network topology
A
A network’s topology is the arrangement, or pattern, in which all nodes on a network are connected together
12
Q
what is a node
A
name given to device connected to network
13
Q
advantages of neworks 4
A
- users can share files
- users can access files from any computer on the network
- communicate with other people (email)
- users can share connections to 0ther network (e.g Internet)
14
Q
Disadvantage of networks 4
A
- increased security risks to data
- malware and viruses spread very easily between Computer
- if server fails, the computer connected to it may. not work
- computers run slower if there is a lot of data travelling on the network
15
Q
what are standards
A
a set of hardware and software specifications that allow manufacturers to create Products and services that are compatible with each other (e.g HTML)
16
Q
what does physical topology mean ?
A
the physical layout of the wires and components which form the network.(how nodes are physically connected)
17
Q
what does logical topology mean
A
the layout which shows how data flows. (how device communicate across the physical topology)
18
Q
examples of topologies
A
bus topologies (physical)
star topology (physical)
physical mesh topology
19
Q
what is a bus topology
A
one cable that connects every device on the network, which is called the backbone.
20
Q
Advantages of bus topology
A
● Relatively inexpensive to set up
● Doesn’t require any additional
hardware
21
Q
Disadvantage of bus topology
A
● If backbone cable fails, the entire network gets disconnected
● As traffic increases, performance decreases
● All computers can see the data transmission
22
Q
what is a star topology
A
each device on the network is connected to a central communication device, such as a Hub or a Switch
23
Q
note of bus topology
A
At each end of the main cable there is a small device called a terminator, which absorbs the signals when they reach the end, to prevent interference
data is sent in one direction
24
Q
Advantages of star topology
A
● Performance is consistent even with heavy network traffic
● If one cable fails, only that single terminal is affected
● Transmits data faster, giving better performance than bus topology
● Easy to add new stations.
● No data collisions
25
Disadvantage
● Expensive due to switch and cabling
● If the central switch fails, the rest of
the network fails
26
what is a switch
a type of central. node that sends each communication to the specific computer it is intended for
27
what are protocols
A protocol is a set of rules defining how two computers communicate with each other.
28
why are protocols important
29
what may protocols be used for
- communication over LAN/WAN
web page transfer
file transfer
email
30
name the 9 most common protocols
TCP
IP
UDP
HTTP
HTTPS
FTP
POP
IMAP
SMTP
31
give the full name for the protocols listed above
TCP : Transmission Control Protocol
IP: Internet Protocol
UDP: User Datagram Protocol
HTTP:Hypertext Transfer Protocol
HTTPS: Hypertext Transfer Protocol secure
FTP: File transfer protocol
POP: Post office protocol
IMAP: Internet Message Access protocol
SMTP: simple Mail Transfer Protocol
32
list where the 9 protocols are found its (area of purpose)
TCP: Communication over LAN/WAN
IP:Communication over LAN/WAN
UDP:Communication over LAN/WAN
HTTP: Web page requests
HTTPS:Web page requests
FTP: File transfers
POP: Email
IMAP: Email
SMTP: Email
33
What is the importance of protocols and standards
- protocol defines a set of rules for data communication (to avoid interference)
they must be standards accross all devices in all networks in order for communication to work
34
What is TCP/IP STACK
work together in the routing of packets through networks (the foundation of communication over the internet)
TCP provides error -free transmission between two routers
IP routes packets across a wide are network (Wn)
35
what does UDP do
an alternative to TCP but has no error checking
sends short messages using datagrams, where speed is more important than accuracy
it uses a simple connectionless transmission model
36
what is HTTP
a way for a client and server to send and receive requests and deliver HTML web pages (used for web rendering)
- it is the fundamental protocol of the World Wide Web
37
What is the difference between HTTPS and HTTP
both do the same Job https provides more security through encryption and authentication (the process of proving that some fact or some document is genuine)
an encrypted version if http
38
when should HTTPS be used
must be used whenever a website deals with sensitive information such as passwords or bak account details
39
what is FTP
a protocol used for sending files over network (computers),usually on WAN
40
what can be used on top of FTP
FTp clients which are software applications that sit on top of the actual FTP protocol
41
what are the 3 protocols that are used in mail servers to deal with email
POP3
IMAP
SMTP
Mailing protocols, used for email access.
42
What does the SMTP do
transfers outgoing emails between servers.
SMTP primarily sends messages to a server for forwarding.
43
what does the POP3 do
POP3 is the most recent version of POP
retrieves emails form a ,ail server and transfers the, to your device, removing them from the server in the process
44
what does the IMAP do
keeps emails on the mail server, allows you to access your email wherever you are, from any device
45
what is a standard
an agreed set if rules for manufacturers and developers to follow
USB (hardware)
HTML (software)
46
difference between internet and the WWW
The Internet is a network of networks which allows computers on opposite sides of the globe to communicate with each other using a back bone to connect
www is a service on the internet
47
describe the process of internet when used by a user(at home)
the place is usually connected by a wireless router
- the router is connected to an internet service provider (ISP) via a fibre optic cable or telephone connection
-Isp is connected to a domain name server and other routers that make up the backbone of the internet
(routers may be WAN/LAN)
48
how does network able to communicate via internet
TCP/IP Stacks A stack of networking
protocols that work together passing packets during communication
49
describe what happens in the application layer
top of the stack.
It specifies what
protocol needs to be used in order to relate the application that’s being sent.
e.g email needed FTP, Web browsing needs HTTP
50
describe what happens at the transport layer
The transport layer uses TCP to establish an end-to-end connection
between the source and recipient computer.
I charge of spliting data into packets , the total number of packets the original data was split
up into and the port number being used for communication.
51
what happens if data packets get lost
the transport layer requests retransmissions of these
lost packets.
52
describe what happens in the internet layer or network layer
users the Ip to address packets with the source and destination ip adresses
the router is what uses the IP
addresses to forward the packets.
○ The sockets are then used to specify which device the packets must be sent
to and the application being used on that device.
53
what is a socket address
the combination of the IP address and the port numbe
54
what happens at the link layer
connection between the network devices, it adds the MAC address identifying the Network Interface Cards of the source and destination computers.
55
what happens to layer when thing is at its destination
it is passes back up
this time from link to the application ()present the image for the user in browser
1. the MAC address is removed by the link layer, then the IP addresses are removed by the Network Layer, then the transport layers remove the port number and reassemble the packets. Finally, the application layer presents the data to the recipient in the form it was requested in.
56
2 type of internet adresses
Mac adresses
ip addresses
57
what is a MAC address
a unique serial number assigned to each network interface controller (NIC) . This allows a network to uniquely identify any device each time the device connects to a network.
58
notes about MAC adress
every physical device has a unique Mac address
switches learn and store the Mac ADRESSNFOR CONNECTED lan
59
why aren't router used to store MAC address
too many Mac address which would take too long to find a particular address ro decide which connection to route traffic down
so they routers cache some IP address
60
how can we think of Mac and ip address
MAC address tells who you are
IP address tells me where you are
61
why can MAC address work on the internet
there are too many devices which is why it is suitable for LAN devices
62
what is a DNS
domain name system (DNS) is the system used to name and organise internet resources.
63
what is the most popular service that the internet offers
World Wide Web
64
what is the World Wide Web
all the public websites or pages that users can access on their local computers and other devices through the internet.
65
what is a domain name
a domain name is a name given to a website which corresponds to an IP address
66
what is the role of the domain name server
to translate these domain names into IP addresses when we wish to access a website.
67
how do DNS categorise domain name
in a hiercahy domain system
TLD : which could either be generic such as .com/.org or could be country TLD such as .uk/.es
2LD: which is a 2nd level domain
3LD : name of the site
68
what is a URL
the address that is used in the web browser to request a resource (web page) from the world wide web.
the entire thing
http://www.bbc.co.uk/index.html.
69
describe how is a user allowed to surf the internet
1. user request URL via a browser
2.browser sends the domain name to DNS
3.the DNS maps the domain name to the IP address and returns it to the browser
4. A GET request fors the web page or resource is sent to the web server using the IP address
4. The requested web page or resource is returned to the user's web browser
70
describe in detail the process of DNS
1. URL is received by a DNS resolver server
2.The server queries a DNS root name server
3.The root server responds with the address of the TLD e.g .com
4.The resolver makes a request to the .com TLD server
5.The TLD server then responds with IP address of the domain name server google.com
6.recursive resolver sends a query to the domain name server
7. the IP address of Google.com (8.8.8)
is the returned to the resolver from the name server
the DNS resolver responds to the web browser with the IP address
71
what is an important understanding of the DNS summary of dns process
the DNS Is number of different and separate domain name servers. their overall goal is the same typing url and if exists it will return the IP address
72
what is the purpose of WI'Fi
a wireless networking technology providing high speed internet and network connection
73
how do devices connect to internet
WAP (wireless network access point )
74
how do network communicate
via data packets
75
what are data. packets
data broken into chunks that contain vital and various types of information and assembled again at the receiving end
76
2 methods which networks use to exchange data
circuit switching and packet switching
77
what is packet switching
Packet switching is a method of communication in which data is communicated using packets across a network. In this method of communication, packets are sent across the most efficient route, which can vary for each packet.
78
advantages of packet switching
- Multiple methods to ensure data arrives intact eg. checksums and cyclic redundancy checks
-Multiple routes can be used between devices, so if one path breaks, another can be used.
-Packets can be transferred over very large networks to allow communication globally.
79
disadvantages of packet switching
- Time is spent deconstructing and reconstructing the data packets
-Must wait for all packets to arrive before data can be received.
80
what is circuit switching
Circuit switching is a method of communication where a direct link is created between two devices.
his direct link is maintained for the duration of the entire conversation between devices. Circuit switching requires the two devices to transfer and receive data at the same rate.
81
Advantages of circuit switching
Data arrives in a logical order which results in a quicker reconstruction of the data.
Enables two users to hold a call without delay in speech
82
disadvantages of circuit switching
-Bandwidth is wasted during periods of time in which no data is being sent.
- Devices must transfer and receive data at the same rate
- Using switches means electrical interference may be produced which can corrupt or destroy data.
- Ties up sections of the network which cannot be used by others data until transmission has been completed
83
what is a bandwidth
is a measure of the data transfer rate or capacity of a given network.
the speed and quality of a network.
84
compare circuit switching vs packet switching
circuit switching
- physical path between source and destination
- all plackets use the same path
- reserves bandwidth in advance
- can cause a lot of bandwidth wastage
- no store and forward transmission
packet switching
- no physical path
packets travel independently
does not receive bandwidth
no bandwidth wastage
supports store and forward transmission
85
what is a client server
consists of two parts the client and server
The
server is a powerful, central computer. The server holds all of the important information and resources and has greater processing power than the terminals, it waits for request from clients. The client accesses data, services and files from the server it initialises communication
Clients can request to use the server.
86
what are the advantages of client server
More secure as data is stored in one location
● Central backups are carried out so there is no need for individual backups
● Data and resources can be shared between clients
87
disadvantages of client- server
● Relatively expensive to set up/maintain
● Functionality of terminals depends
on the server; if this fails,
performance falls
● Trained staff are required to
maintain the server
requires IT specialists
88
example of a client server
school
89
what does a server do in client -server architecture
provide services such as
managing printing jobs
provide emails device
runs regular back up of data
manages access to the internet
controls access and security fir a shared file store
90
when should client - server models be used
organisations with a large number of computers or situation where many computers needs access to the same information
91
what is a peer to peer model
all computers have equal status they are connected to each other to share files. - no computer has control over the network. each device acts as both a server and client as it can both provide and request resources
92
advantages of peer to peer network
● Cheaper to set up
● Allows users to share resources
● Easy to maintain
● Not dependent on a central server
● Specialist staff are not required
93
Disadvantage of peer to peer
● Impossible to trace the origin of files
● Backups must be performed
separately
● Poorer security
● May be difficult to locate resources
94
what are the need for network security/ its aim
- only allow authorised users to access what they need
- prevent unauthorised access(intrusion and hacking)
minimise the potential damage caused by unauthorised access
95
define hackers
a person who attempts to gain access goto a computer system with the intent of damaging data. somehow hamming the system
96
types of hackers
- black hat hackers
- white hat hackers
- grey hat hackers
97
what is black hat hacker
they attempt to Gain access via nefarious mean, typically to steal company secrets / cause damage
98
what is a white hack hackers
security experts (employed by a company )use expertise to try and find vulnerabilities and fix them
99
what is a white hack hackers
security experts (employed by a company )use expertise to try and find vulnerabilities and fix them
100
what are grey hat hackers
both black and white hat hackers
no employed by a company bu attempt to find flaws and vulnerability in company wide computer systems as a hobby
101
define malware
term that covers any computer code written with the intent to frustrate or harm
102
reasons why malware is created/ effects of malware
- delete , corrupt and encrypting files
- causing computers to crash, reboot files
- reducing network speeds
- logging keyboard inputs and sending them to hackers
103
types of malware
- virus
worm
trojan
phishing
spyware
104
define viruses
pieces f code capable of copying themselves and spreading throughout a system
105
why are viruses used
to have a detrimental effect like corrupting a file system or destroying data
106
what is spyware
form of malware that covertly obtains information pbpput a users's computers activities by transmitting data from their device
107
uses of spyware
to harvest sensitive and personal data
visited web pages
download habits
passwords
cookies
108
define works
standalone program that does not require a user to run it fr it to spread (exploit vulnerability)
109
what are trojans
type of malware that disguises itself as legitimate code or software to trick user into executing it
110
what can trojans do
performs malicious actions such as data theft, redirecting search requests, installing further malware, or opening a “backdoor” for remote control of your computer.
111
what is phishing
using email to manipulate a victim into visiting a fake email and giving away personal information
112
what is phishing (type of social engineering )
using email to manipulate a victim into visiting a fake email and giving away personal information
113
how can networks prevent being threatened
use methods of network security
114
what are the types of network security
firewalls
proxies
encryption
antivirus
secure passwords
115
is pharming
similar to phishing but the server misdirects users to fraudulent websites without their knowledge (winning 4k)
116
what are firewalls
device designed to prevent unauthorised access to a network
117
how do firewalls work
consists of two network interface cards (NICs) between the user and the Internet. The firewall passes the packets between these two NICs and compares them against a set of rules set by the firewall software
118
why are firewalls used
block certain ports
prevent : unauthorised internet traffic form outside LAN
Users in LAN from accessing parts of the internet prohibited by the company they work for
119
why is securing password minimising network threats
makes it more difficult to guess (through algorithms)
however enforvong overly strict rules ca cause users to forget it
120
ways of making password more secure
Up/Low case letters
- not the same as other passwords
must be changed every x days
cat be based on name
of a certain length
121
types of network hardware
Network interface cards (NIC)
Switch
Wireless Access Point (WAP)
Routers
Gateway
122
define Network interface cards (NIC)
A network interface card is the card required to connect a device to a network. This is usually built into the device and assigns a unique media access control (MAC) address to each device. The MAC address is a 48-bit value coded into the device and is usually written as a twelve digit hexadecimal number.
123
what does an TCP do
used to break up the data into packets, it will keep track of the packets, and it will re-assemble the packets
124
What does the IP do
IP is used to deliver each individual packet.
