Networks Flashcards

1
Q

Define

network.

A

an arrangement of two or more computers that are connected together for the purpose of sharing resources and data

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are some advantages of a

network?

(5)

A

they allow multiple users to:
- share data files with each other
- share hardware devices (e.g. printers, speakers)
- share an internet connection and internet services (e.g. www and email)
- communicate with each other (e.g. email, messaging)
- work together using web-based software (e.g. shared calendars, virtual meetings)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the

internet?

A

the world’s largest public WAN, a global system of interconnected networks, linking together billions of digital devices worldwide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are some characteristics of

LANs?

  • geographic area?
  • ownership?
  • security?
  • speed?
  • cost?
  • topology?
  • type of addressing?
  • hardware forwarding packets?
A
  • small
  • private individuals
  • more secure
  • slower cables but many less users
  • cheaper as there is less hardware required
  • bus or star or mesh
  • MAC addressing
  • switch
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are some characteristics of

WANs?

  • geographic area?
  • ownership?
  • security?
  • speed?
  • cost?
  • topology?
  • type of addressing?
  • hardware forwarding packets?
A
  • large
  • businesses and organisations
  • less secure
  • faster cables but shared amongst millions of connections
  • more expensive
  • partial mesh
  • IP addressing
  • router
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is a

node?

A

a device on a network

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is a

network topology?

A

how different nodes on a network connect to one another

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What does a

bus topology consist of?

(3 key points)

A
  • all the nodes on the network are connected to a single cable, known as the backbone
  • messages are sent along the cable in the form of electronic signals
  • a terminator at each end absorbs signals that have reached the end of the cable (preventing them from bouncing back and causing interference)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the advantages of a

bus topology?

(3)

A
  • relatively inexpensive to install since very little cabling is needed
  • if one node fails, the rest can still communicate with each other
  • easy to add extra devices to the network
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the disadvantages of a

bus topology?

(3)

A
  • if the cable is cut or damaged the whole network stops functioning
  • the more devices that are added, the more collisions will occur and the slower the network will run
  • all nodes on the network ‘see’ all data traffic (this may be a security risk)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is an example of a use of a

bus topology?

A

small, short-term networks

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What does a

star network consist of?

(2 key points)

A
  • every node is connected to a central node (likely a switch)
  • all data traffic passes through the central node, which is responsible for routing to its destination
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the advanatges of a

star topology?

(5)

A
  • if one node goes down, the rest of the network will continue functioning
  • a damaged cable doesn’t stop the network from working, just the device connected to it
  • data traffic is only sent to the intended recipient and not passed through any other nodes (making it secure)
  • it is easy to locate faults
  • nodes can be added and removed without having to take the entire network offline
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the disadvantages of a

star topology?

(3)

A
  • if the central node fails, then the rest of the network stops functioning
  • network performance and maximum number of nodes depends on the capacity of the central node
  • a lot of cabling is required, making it difficult and expensive to set up
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is an example of a use of a

star topology?

A

home networks

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What does a

mesh network consist of?

(2 key points)

A
  • each node is connected to multiple other nodes eith by cable or wirelessly
  • communication in peer-to-peer (P2P) as there is no central controlling device
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are the advantages of a

mesh network?

(4)

A
  • very fault tolerant - if one node fails, messages are rerouted
  • nodes can be added and removed without having to take the entire network offline
  • very scalable, any number of additional nodes can be added
  • very high performance
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the disadvantage of

mesh networks?

A

a wired mesh network is difficult and expensive to install

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the

structure of the internet?

(4 levels)

A
  1. Every device connected to the internet is part of a network.
  2. Local networks connect to the internet via a Point of Presence (POP) (provided by an Internet Service Provider (ISP)).
  3. The ISP’s network is connected to a high-level network owned by a major telecommunication company (BT in the UK).
  4. Network Access Points (NAPs) interconnect the internet backbones to form a worldwide network.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What are some examples of

Internet Service Providers?

(3)

A
  • Virgin Media
  • BT
  • Sky
21
Q

What do

routers do?

(2)

A
  • forward data from one network to another across the internet from source to destinatinon
  • keep each other up to date about traffic conditions in their part of the network, so that data can be routed away form congested areas
22
Q

What is

IP?

and what does it stand for?

A

a set of rules governing data transfer on the internet

internet protocol

23
Q

What do

IP addresses do?

A

uniquely identify devices on a network

24
Q

What does an

IPv4 address look like?

A

13.255.182.0

(each of the four bytes is expressed as a decimal number between 0 and 255 separated by dots)

25
Q

What does an

IPv6 address look like?

A

fd2a:1450:4013:c01:0:0:0:5e

(eight 16-bit hexadecimal numbers separated by colons)

26
Q

Why was

IPv6 introduced?

A

IPv4 allows more than 4 billion devices to be uniquely identified. This is no longer anywhere near sufficient.

27
Q

What is the purpose of

IP addresses?

(2)

A
  • facilitate routing across the Internet
  • provide a sender & destination unique addressing scheme

this is temporarily allocated to devices whilst they are connected to the Internet/ a WAN

28
Q

What information is stored in the

metadata of a packet?

(5)

A
  • IP address of source
  • IP address of destination
  • sequence number of packet
  • total number of packets
  • checksum
29
Q

How do

routers send packets to their destination?

(4)

A
  1. The router inspects the packet header to find the destination address.
  2. It then uses a routing table to determine where to send the packet next. (It is likely that a packet will be forwarded from one router to another several times before reaching its destination.)
  3. If there is congestion on one route, the next packet to arrive will be sent a different way to avoid it.
  4. Once a packet arrives at its destination, the checksum formula is applied to the data. If the generated checksum does not match, the destination will request the packet to be resent from the source.

Packets may arrive at their destination via different routes may be out of sequence on arrival.

30
Q

Define

speed.

A

the transfer rate of data from source to destination

31
Q

Define

range.

and give its unit.

A

the maximum distance a signal can travel before becoming disrupted

metres, m

32
Q

Define

latency.

and give its unit.

A

the length of time it takes between a transmission being sent and received

Ms (higher is worse)

33
Q

Define

bandwidth.

and give its units.

A

the maximum transfer rate of data from source to destination

bits per second, bps (higher is better)

34
Q

What equation links

file size, time and bandwidth?

A

file size = time x bandwidth

35
Q

Define

protocol.

A

a set of rules that allow devices to communicate

36
Q

What are the most common forms of

wired transmission media?

A
  • copper wire
  • fibre optic cable
37
Q

What does an

unshielded twisted pair copper wire consist of?

A

four pairs of thin copper wires covered in plastic insulation that are twisted together to help reduce interference

38
Q

What does a

fibre optic cable consist of?

A

one or more very thin strands of glass, surrounded by several layers of protective material, encased in an outer sheath

39
Q

What are the key characteristics of a

copper wire?

  • how it works?
  • range?
  • speed?
  • latency?
  • uses?
A
  • transmits data as electrical pulses
  • short (up to 100m)
  • up to 10Gbps
  • high (suceptible to interference)
  • connecting computers and other devices on a LAN
40
Q

What are the key characteristics of a

fibre optic cable?

  • how it works?
  • range?
  • speed?
  • latency?
  • uses?
A
  • transmits data as pulses of light
  • large (can transmit data over long distances with no loss of signal strength)
  • high - up to 100Gbps
  • low (less subject to interference
  • connecting LANs together to form WANs
41
Q

What are the characteristics of

wired networks?

  • installation?
  • flexibility?
  • reliability?
  • security?
  • range?
  • bandwidth?
  • latency?
A
  • time-consuming and disruptive, can present a trip hazard
  • not flexible - the number of NAPs and their locations have to be determined at the outset, expanding or changing the LAN once it is up and running will require additional cabling
  • reliable and delivers a consistent speed - because it is less susceptible to interference
  • very secure - data can only be accessed by devices that are physiclly attached to the network, not easy to intercept or eavesdrop
  • can transmit data over long distances and between different buildings on the same site
  • fast - up to 10Gbps per connection
  • low
42
Q

What are the characteristics of

wireless networks?

  • installation?
  • flexibility?
  • reliability?
  • security?
  • range?
  • bandwidth?
  • latency?
A
  • less time-consuming and disruptive to install (than wired)
  • very flexible
  • performance can be inconsistent because WiFi signals are subject to interference
  • less secure - data needs to be encrypted to prevent eavsdropping or interception
  • theoretical range of 100m (but physical objects and interference can obstruct the signal)
  • slower (than wired)
  • high
43
Q

What does

HTTP stand for?

and what is it used for?

A

Hyper Text Transfer Protocol

requests and responses between web browser & web servers

44
Q

What does

HTTPS stand for?

and what is it used for?

A

Hyper Text Transfer Protocol Secure

encryption communication between browser & web server

45
Q

What does

FTP stand for?

and what is it used for?

A

File Transfer Protocol

sending and receiving files over the internet

46
Q

What does

SMTP stand for?

and what is it used for?

A

simple mail transfer protocol

sending emails

47
Q

What does

IMAP stand for?

and what is it used for?

A

Internet Mail Access Protocol

reading/receiving emails

this leaves the email on the mail server

48
Q

What does

POP3 stand for?

and what is it used for?

A

Post Office Protocol

reading/receiving emails

this deletes the email off the mail server