computer networks

Question 1

LAN meaning

Answer 1

 Covers small geographical area.
 Doesn’t require external infrastructure.

Question 2

WAN meaning

Answer 2

WAN:
 The computers connected are geographically distanced/far apart.
 Organisations hire external infrastructure from other companies.

Question 3

whats a nic and its function

Answer 3

Network Interface Card (NIC):  Allows a device to connect to a network.
 Each NIC has a unique MAC address.

Question 4

switch meaning (3)
what does it do with packets

Answer 4

Switches:
 Acts as the central hub in a star topology and connects devices together on a LAN.
 Receives and sends packets to its destination.
 Uses the MAC addresses of the devices connected to it.

Question 5

router meaning

Answer 5

 Transmits and receives packets and identifies the most efficient path to the correct destination.
 Assigns IP addresses to devices.
 Connects networks together (e.g. LAN to Internet).

Question 6

Transmission Media examples
and do they have good or bad bandwidth and range

Answer 6

Transmission Media:
o Copper cables (coaxial) have small bandwidth and short range.
o Fibre-optic cables have high bandwidth and long range.
o Radio waves (Wi-fi, Bluetooth) have good bandwidth and good range.

Question 7

four factors that affect network performance

Answer 7

Wi-fi Frequency
Interference
Bandwidth
number of devices connected

Question 8

what do fibre optic cables do and pros

Answer 8

transmits data by light signals
 Very fast, reliable, and doesn’t suffer any interference (but is expensive).
 Can transmit over very large distances without loss of signal quality.

Question 9

4 advantages of peer to peer networks

Answer 9

 No server is required (cheap).
 Computers are independent and are directly connected to each other.
 Small initial cost and less maintenance.
 If any device fails, the network can continue.

Question 10

how does bandwidth affect network performance

Answer 10

 Transmitting large files will take up more bandwidth than smaller files, increasing the traffic.
 The greater the bandwidth, the better the network performance

Question 11

how does number of devices connected affect network performance (3)

Answer 11

 More devices mean that more data is being transmitted at a time, so the transmission of data is slower.
 Bandwidth will be split between all the devices so there is less bandwidth for each device.
 More collisions will occur, so more data has to be retransmitted.

Question 12

how does interference affect network performance

Answer 12

 Causes errors which means overlapping signals need to be retransmitted, increasing the traffic.
 Objects such as walls can block/weaken the signal.

Question 13

how does wifi frequency affect network performance

Answer 13

 5GHz can transfer data faster than 2.4GHz.
 2.4GHz has a longer range which allows access from further distances.

Question 14

4 client server networks advantages

Answer 14

 Files are stored centrally so it is easier to keep track of them and backups are easier.
 Easier to install and update software.
 Easier to manage network security (e.g. user access levels).
 More reliable as servers are always on.

Question 15

for disadvantages to peer to peer networks

Answer 15

 Computers will have files stored individually so back-ups are more complicated.
 Software needs to be installed/updated individually.
 Computers need their own security.
 Less reliable (data can be lost) and there are performance issues when many users access files from a peer.

Question 16

3 disadvantages of client server

Answer 16

 Expensive to setup and needs someone to maintain and manage the server.
 If the server fails, clients lose access to services.
 Server can become overloaded if there are too many client requests at once.

Question 17

what are hosted on web servers and what is the function of web servers

Answer 17

o Websites are hosted on webservers.
o Stores data and receives requests then executes/responds to them.
o Returns confirmation or error of the upload.

Question 18

peer to peer networks meaning

Answer 18

all devices are connected equally and directly without a server

Question 19

wired networks 3 pros

Answer 19

Wired Connections:
 Faster speeds and more stable.
 Data transmitted over cable is less susceptible to interception (more secure).
 More reliable network performance, less affected by interference/physical obstructions.

Question 20

ethernet cables function and pros

Answer 20

 Uses ‘twisted pair’ of copper wires to reduce internal interference.
 Reliable, high bandwidth (fast), and good range.
 Has inbuilt security and has a low purchase cost.
 Used by nearly all manufacturers and used in many devices, allowing good compatibility.

Question 21

wifi meaning and pros

Answer 21

Used by multiple devices to connect to a LAN at the same time.
 Good range (up to 100m).
 Higher bandwidth than Bluetooth.

Question 22

bluetooth meaning and 2 cons

Answer 22

Bluetooth:
Direct connection between 2 devices so data can be shared.
 Short range (typically 10m).
 Lower bandwidth than Wi-Fi.

Question 23

wired connections cons 2

Answer 23

1) Cabling is expensive and difficult to install.
2) Limited mobility.

Question 24

what is a network

Answer 24

a wired or wireless medium that allows 2 or more computers to connect
(purpose of communication)

Question 25

5 advantages of using wireless connections

Answer 25

 Easy to connect and allows more devices to connect.  Compatible to more devices.  Devices can be used in different areas within the range.  Cheaper to purchase and setup new devices as there is no cost for new wires/hardware.  Fewer trip hazards from long wires.

Question 26

4 disadvantages on wireless connections

Answer 26

 Prone to interference and there is a limited range of signal (compared to fibre optic).  More users mean less bandwidth, causing a slower rate of transmission.  Higher chance of collisions, resulting in a less stable connection.  Increased risk of security concerns e.g. hackers.

Question 27

IPv4 (4) how many bits separated by what what is binary converted to how many between each group

Answer 27

IPv4: o Uses 32 bits, split into 4 groups of 8 bits o separated by full stops o binary is converted to denary o Each group can be between 0 – 255. o e.g. 00100101.10011001.00111110.10001000 is translated into 37.153.62.136

Question 28

IPv6 (4) how many bits separated by what what is binary converted to what is each 16 bit converted to

Answer 28

o Uses 128 bits, split into 8 groups of 16 bits o separated by colons o binary is converted to hexadecimal. oEach 16 bits are converted into 4 hexadecimal numbers. o e.g. 2001:0db8:85a3:0000:0000:8a2e:0370:7334

Question 29

mac address how many bits used split into how many groups separated by what

Answer 29

Uses 48 bits split into 6 groups of 2 hexadecimal numbers separated by colons. e.g. 00:1A:2B:3C:4D:5E

Question 30

standards meaning

Answer 30

Standards – provide rules for hardware and software to allow compatibility between them.

Question 31

what is bandwidth

Answer 31

measure of the amount of data that the medium can transfer over a certain amount of time

Question 32

what is network traffic

Answer 32

the amount of data being transferred by the medium over a certain amount of time

Question 33

protocols meaning

Answer 33

Protocols – an agreed set of rules for how computers should communicate:

Question 34

layers pros 4

Answer 34

 Layers are self-contained and not reliant on other layers (one can be changed without affecting others).  Separates tasks allowing developers to concentrate on one aspect of the network and program individually.  Simpler to manage.  Having standards for each layer allows compatibility between different hardware/software.

Question 35

how do transmission errors occur

Answer 35

when the signal from 2 devices trying to communicate at the same time along the same communication channel collides

Question 36

what is a server

Answer 36

computer that manages and stores files

Question 37

what is a client

Answer 37

a computer that relies on other computers to provide and manage data

Question 38

layers meaning and what does it communicate to

Answer 38

seperate levels in a system, where each layer has a specific job and only communicates to the layers above and below it.

Question 39

are networks wired or wireless

Answer 39

can be either

Question 40

compare the cost, distance and transmission speed of twisted copper wires and fibre optic wires

Answer 40

copper - cheap fibre - expensive copper - 100m fibre - 2km copper - slow fibre - fast

Question 41

how does data travel through twisted copper wires compared to fibre optic cables

Answer 41

copper - electrical fibre - light

Question 42

4 types of connection devices

Answer 42

hubs switches waps routers

Question 43

difference between a hub and switch

Answer 43

hub broadcasts messages to all devices on a network whereas switches only sends the message to the recipitant

Question 44

how does a switch improve network performance

Answer 44

cuts down unnecessary transmissions

Question 45

what does the wap stand for and do

Answer 45

wireless access point and allows wireless devices to connect to a wired network using Wi-Fi

Question 46

what is the internet and example

Answer 46

A collection/network of computer networks (WAN) eg The World Wide Web (WWW) is a service that runs on the Internet.

Question 47

Mesh Topology meaning and advantage and disadvantage

Answer 47

 All devices are connected to each other.  If a device fails, data can be sent along a different route (reliable).  Cabling can be very expensive and requires lots of maintenance.

Question 48

what is hosting

Answer 48

 Using servers to provide services (e.g. Webservers host webpages, File servers store/retrieve files.  Clients request these services from a server.

Question 49

Star Topology meaning

Answer 49

Star Topology: All devices are connected to a central point (a switch that is connected to a server).

Question 50

what does a DNS do

Answer 50

translates a URL / domaine name into an IP address by finding it in its database and returns the IP to the browser. The browser sends a request to the webserver which processes the request for the website and sends the webpage to the user.

Question 51

what is the cloud

Answer 51

Network of servers that store data.

Question 52

5 advantages of cloud storage

Answer 52

1) Users can access data from any device connected to the Internet from anywhere. 2) Provides security, backups, and automatic updates. 3) No need to buy expensive hardware or pay IT staff to manage it. 4) Easy and quick to share files with others. 5) Environmentally friendly.

Question 53

disadvantages of using cloud storage (5)

Answer 53

1) Requires an internet connection so it can be slow 2) Reliant on third party for security and backups. 3) Data stored will be vulnerable to hackers and other threats such as interception when transferring data. 4)Issues around who has ownership over cloud data. 5) Subscription fees for cloud storage/applications can be expensive.

Question 54

star topology advantages 4

Answer 54

 If a device fails, it does not affect the rest of the network.  Easy to add new devices.  Fast and reliable  Fewer data collisions can occur.

Question 55

star topology 2 disadvantages

Answer 55

 If the switch/server fails, then so will the entire network.  In wired networks, every device needs a cable to connect to the central point, which is expensive.