31-36

Question 1

How are devices connected to each other?

Answer 1

Physical objects that can connect with each other and other systems via the internet.

Question 2

What benefits are there to using a connected computer?

Answer 2

Not expensive
Boosts storage capacity.
Makes file sharing easier
Enhances communication

Question 3

Categorising a network

Answer 3

Networks can be classified based on their geographical coverage.
Networks that are contained within a single building or site are known as Local Area Networks (LANs).
Networks that are connected over a larger geographical area are known as Wide Area Networks (WANs).

Question 4

Why do businesses have WANs?

Answer 4

Big organisations may have their own WANs.
The organisation owns all of the WANs hardware and has full control of the network.
Others cannot use its infrastructure.
This means the network can be very secure.
This is a very expensive option because the infrastructure has to be installed and maintained.

Question 5

Virtual Private Network (VPNs)

Answer 5

An organisation can stimulate its own WAN over the internet by using a Virtual Private Network.
A VPN uses encrypted communication channels over the infrastructure of the internet.
A VPN allows an individual to appear to be connected directly to their organisation’s network.

Question 6

What are protocols

Answer 6

Protocols are sets of rules that govern the communication between devices.
For two devices to communicate, they must use the same protocol.

Question 7

addressing system

finding the device you need

Answer 7

Another key element needed for communication is an addressing system.
Each device on a network needs a unique address so that connections can be made to it.
IP addresses are used on the internet.
MAC addresses are used on LANs.

Question 8

IP address

Answer 8

In a WAN, an IP address is used to identify an individual device or network access point.
There are two types, version 4 and version 6.
IPv6 addresses are longer so they can address a greater number of unique devices.

Question 9

Explain the benefits an organisation gets from using a WAN.

Answer 9

Able to share data and resources from different sites.
Owning the network hardware gives more control.
A WAN can be more secure than the VPN alternative.

Question 10

LAN definition

Answer 10

local area network

a network that covers a relatively small geographical area, often a single site

Question 11

WAN definition

Answer 11

wide area network

a network that covers a large geographical area and connects together multiple LANs

Question 12

Network definition

Answer 12

an arrangement of computers and other digital devices connected together to share resources and data

Question 13

Internet definition

Answer 13

the worlds largest public WAN.

it is a global system of interconnected networks, linking together billions of digital device worldwide.

Question 14

VPN definition

Answer 14

virtual private network

a non-physical network, hosted on a physical network such as the internet.

a VPN provides secure, encrypted communications as if the suer were on the organisations own secure network

Question 15

protocol definition

Answer 15

a set of rules, which if followed, allow devices to connect

Question 16

IP address definition

Answer 16

internet protocol address

a unique identifier assigned to each device connected to a network

Question 17

What does speed mean?

Answer 17

The term ‘download speed’ refers to how much data can be downloaded per second over a connection.
There are a number of factors that can affect the speed of a connection.
The most important two are the bandwidth and latency.

Question 18

Bandwidth

Answer 18

Bandwidth is the maximum amount of data that can be transmitted over a connection per second.
It is a measurement of capacity.
It is measured in bits per second (bps).
(Amount of information transferred in a second).

Question 19

Latency

Answer 19

Latency is the time taken for a transmission to reach its destination.
It is measured in milliseconds.

Question 20

Ping

Answer 20

This is a way of measuring latency.

It times a single transmission as it travels to a server and back again.

Question 21

measuring speed units

Answer 21

bits per second = 1 bit per second
kilobits per second = 1000 bit per second
megabits per second = 1,000,000
gigabits per second = 1,000,000,000

Question 22

units (file size)

Answer 22

bit
byte
kibibyte
mebibyte
gibibyte
tebibyte

Question 23

Calculate transmission times

Answer 23

Time = file size (in bits) / network speed (in bps)

Question 24

How long will it take to download a 20MiB file over a 12 Mbps connection?

Answer 24

Convert the file size into bits
20 x 8 x 1-24 x 1024

Convert the speeds to bits per second
12 x 1000 x 1000

Arrange the size and speed expression
(20 x 8 x 1024 x 1024) / (12 x 1000 x 1000)

Question 25

Two methods used to transmit data are...

Answer 25

Serial | Parallel

Question 26

serial data transmission

Answer 26

Serial data transmission sends data bits one after another over a single channel

Question 27

Parallel data transmission

Answer 27

Parallel data transmission sends multiple data bits at the same time over multiple channels.

Question 28

definition of a channel

Answer 28

A channel is used to convey an information signal, for example a digital bitstream, from one or several senders (or transmitters) to one or more received. A channel has a certain capacity for transmitting information, often measured by its bandwidth or its data bits per second.

Question 29

``` bandwidth or latency what is the biggest impact for: a) downloading a film b) playing an online game c) video conference d) loading a webpage e) streaming a film to watch now ```

Answer 29

a) Bandwidth b) latency c) Latency and bandwidth d) Bandwidth e) Latency and bandwidth

Question 30

The time estimate for downloading a 22GiB file over a 54Mbps connectio

Answer 30

Time = file size (in bits) / network speed (in bps) | Time = (22 x 8 x 1024 x 1024 x 1024 ) / 54 x 1000 x 1000

Question 31

The time estimate for downloading a 45KiB file over a 4Gbps connection.

Answer 31

Time = file size (in bits) / network speed (in bps) | Time = (45 x 8 x 1024) / 4 x 1000 x 1000 x 1000

Question 32

The maximum speed for uploading a 25MiB file in 4 seconds.

Answer 32

Time = file size (in bits) / network speed (in bps) Speed = (25 x 1024 x 1024 x 8) / 4

Question 33

The maximum file size (MiB) that can be uploaded at 12Mbps in 30 second.

Answer 33

Time = file size (in bits) / network speed (in bps) | 30 x 12 x 1000 x 1000) x (8 x 1024 x 1024

Question 34

Wired vs wireless

Answer 34

All methods of transmitting data are either wired or wireless. The difference is simple: Wired transmission involves making a physical connection from one device to another (USB or ethernet cable). Wireless transmission uses no physical connection. Instead it used radio waves (Bluetooth, Airdrop and NFC).

Question 35

Cables

Answer 35

Copper is more common as it was invented over 150 years ago. | Fibre-optic cables are a modern alternative that has vastly higher bandwidth and lower latency

Question 36

broadband

Answer 36

Broadband is a type of high-capacity internet connectivity that is all over the country

Question 37

FFTC

Answer 37

(fibre to the cabinet) - fibre optic cable runs to green street-cabinets. Copper cables then link homes to the cabinets (a short distance).

Question 38

FTTP

Answer 38

(fibre to the premises) - used for businesses. In this approach, the final stretch from the cabinet to the business uses other fibre optic cables.

Question 39

Copper cable + fibre optic cables

Answer 39

Copper cables : data is transmitted as electrical pulses. | Fibre optic cables : data is transmitted as pulses of light.

Question 40

``` copper cable: How it works Range Speed Latency Usage ```

Answer 40

Four twisted pairs of copper wires enclosed in a protective case. 100 cm 10 - 1000 mbps 13 - 14.2 microseconds LAN

Question 41

``` Fibre optic cables: How it works Range Speed Latency Usage ```

Answer 41

Light travels down a fibre optic cable by bouncing off the walls of the cable repeatedly. 2,000 metres 10 Gbps / 25-300 Mbps 3.33 microseconds / km Internet / WAN

Question 42

microwaves and radio waves

Answer 42

Microwaves and radio waves are frequently used to transmit data. This involves converting the binary data into an electromagnetic wave using a specific protocol. Examples of the protocols used are Wi-Fi and Bluetooth

Question 43

Wireless data transmission has its limits:

Answer 43

Generally the range is limited to a few metres. Easily interrupted by other signals or physical obstacles. Has much lower bandwidth than wired connections which makes transfer slow. Security is a concern as wireless signals can be intercepted by others.

Question 44

Wireless access point

Answer 44

In a WLAN, there will be a wireless access point which sends and receives wireless transmissions to and from the other devices. A WAP is usually part of a box you call the broadband router. The router will be connected to an internet access point in order to connect the WLAN to the internet.

Question 45

Describe how devices are connected on a wireless network.

Answer 45

Wi-Fi uses radio waves to transmit data to and from a wireless access point. The router, connected to the wireless access point, distributes signals to the devices.

Question 46

wired vs wireless : installation

Answer 46

Wired networks may be more difficult to install because every device needs a dedicated cable. It may be more difficult to diagnose a problem with a wired network because all the cabling may need inspection. Wireless networks may save cabling costs because not every device needs a dedicated cable. Cables still need to be installed in ceilings and floors to get from the wireless access point to a switch. Wireless access points must also be bought.

Question 47

wired vs wireless : flexibility

Answer 47

Machines cannot move around because they’re limited to the area covered by the actual physical cable. Client machines can move around easily because there is no dedicated cable.

Question 48

wired vs wireless :range

Answer 48

Wired networks can provide transmission over longer distances than wireless networks because the copper media is more effective. Wired networks may need repeaters or boosters to cover distances greater than 100 meters because the signal degrades. Quality may be lost because of walls, floors, or other barriers between the device and the wireless access point. Repeaters and boosters may be required because a wireless signal has a very limited range.

Question 49

wired vs wireless : bandwidth

Answer 49

Wired networks have higher capacities because copper is better at signal transmission than the air. Communications may be slower than on a wired network because transmission through the air cannot support high speeds.

Question 50

wired vs wireless : latency

Answer 50

A wired network is less susceptible to interference from outside sources than a wireless network because the cables themselves have layers of coverings to protect them. An Unshielded Twisted Pair (UTP) is susceptible to interference from the wires inside the cables, but this is very small. Wireless networks are susceptible to interference from other wireless networks or devices because the radio waves can collide with each other. A wireless network’s performance may slow down because too many users are trying to share the same radio wave frequency.

Question 51

wired vs wireless : reliability

Answer 51

Wired networks are usually more reliable than wireless networks because they are less susceptible to interference. A wireless connection may drop completely or the connection may be disconnecting and reconnecting frequently because the connection is unstable for some reason.

Question 52

wired vs wireless : security

Answer 52

A wired network is more secure because it is more difficult (but not impossible), to tap into actual physical cables than it is to tap into radio waves. A wireless connection is susceptible to being intercepted because the radio waves are freely moving through the air.

Question 53

Topology

Answer 53

The way that a LAN is organised is known as its topology. Bus Star Mesh (partial and full)

Question 54

Topology security

Answer 54

Bus - not very secure as all devices ‘see’ all the data traffic. Star - very secure as each transmission is sent directly to the intended recipient. Mesh - reasonably secure as the traffic takes the shortest route to its destination.

Question 55

The internet

Answer 55

The internet's cables (long distance and high bandwidth) travel across the globe are known as the backbone. Each country generally has its own backbone, which can be linked to others using Network Access Points (NAPs). Networks are connected to the internet using a Point of Presence (PoPs) provided by an Internet Service Provider. ISPs are organisations that ‘rent’ bandwidth from telecommunications companies such as BT.

Question 56

definition of WLAN

Answer 56

Wireless Local Area Network a local area network in which connected devices use high frequency radio waved to communicate

Question 57

Definition of ISP

Answer 57

internet service provider an organisation that provided its customers with a connection to the internet

Question 58

Definition of Hub

Answer 58

a common connection point for devices in a star network. when a packet arrives at one port, it is copied to the other port so that all segments of the network can see all packets.

Question 59

Definition of switch

Answer 59

a networking device that recieves and forwards data to a destination node on a network without it passing through any other nodes on route

Question 60

definition of NAP

Answer 60

network access point a piece of networking hardware that connects internet backbones together

Question 61

definition of backbone

Answer 61

A main data route on the internet, owned and operated by a major telecommunications company. Multiple fibre-optic cables are combined together to provide fast data speeds and high capacity bandwidth.

Question 62

definition of DNS

Answer 62

domain name system/server Converts an Internet Protocol (IP) address to a Uniform Resource Locator (URL) for the browser to use.

Question 63

Mesh : how it works

Answer 63

There is no central connection point. Each node is connected to one or more other nodes. Each node can send and receive messages. Each node acts as a relay, passing on a message towards its final destination.

Question 64

star : how it works

Answer 64

Each node is connected to a central device, either a ‘hub’ or a ‘switch’, which acts as a central point. All communications go through this central point. A hub broadcasts messages across the whole network, whereas a switch sends the message to the intended recipient only.

Question 65

bus : how it works

Answer 65

* All the nodes are joined to one cable, called ‘the bus’. | * A terminator is fitted at each end to stop signals reflecting back

Question 66

mesh: advantages and disadvantages

Answer 66

Advantages Wireless mesh networks are becoming more common because they are usually simple and cheap to connect (as they use radio signals). Messages may be received quickly because the route to the destination can be very short. Messages should always get through because there are many potential routes to the same destination. No node should be unreachable because each node should have more than one connection to it. Each node can transmit to and receive from more than one node at the same time because of its multiple connections. Disadvantages Wired mesh networks are relatively uncommon, because connecting all nodes to all other nodes is expensive and impractical. Fully connected mesh networks can be impractical to set up because of the high number of connections required. Maintenance requirements may be high because of the large number of connections.

Question 67

star : advantages and disadvantages

Answer 67

Advantages Failure of one node or its cable does not affect any of the other nodes, because each is separately connected. It is easy to add new devices because you simply connect them to the central point (switch/hub). Star networks tend to have higher performance than a bus topology, because each message is passed only to its intended recipient. Disadvantages If the central point (switch/hub) fails, then the whole network fails because every device is connected to it. A wired star topology may be expensive to install because it can require a lot of cable.

Question 68

bus : advantages and disadvantages

Answer 68

Advantages •It’s easy to install extra devices because you only need a connector for each device. •The cable is inexpensive because there is only a single length. disadvantages •It’s not reliable because when the cable is down, all the devices are down. * It does not perform well under load, because the more devices that are added the more chance there is of data collisions. * It may represent a security risk because every node on the bus receives every transmission.

Question 69

Definition of PoP

Answer 69

point of presence local access point for an ISP. they interconnect internet backbones around the worlds.