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AS Computer Science > Chapter 2 - Networking > Flashcards

Chapter 2 - Networking Flashcards

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1
Q

ARPAnet

A

Advanced Research Projects Agency network

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2
Q

WAN

A

Wide Area Network (network covering a very large geographical area)
Typically consists of LANs connected via public communications networks
This means it may be a private network and passwords/user IDs are required to access it

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3
Q

LAN

A

Local Area Network (network covering a small area such as a single building)

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4
Q

MAN

A

Metropolitan Area Network
Larger than LAN smaller than WAN

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5
Q

File server

A

Server on a network where central files and other data are stored and can be accessed by a user logged onto the network

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6
Q

Hub

A

Hardware used to connect together a number of devices to form a LAN that directs incoming data packets to all devices on the network

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7
Q

Switch

A

Hardware connecting a number of devices to form a LAN that directs incoming data packets to a specific destination address only

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8
Q

Router

A

Devices which enables data packets to be routed between different networks (eg. can join LANs to form a WAN)

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9
Q

Modem

A

Modulator demodulator
Device that converts digital data to analogue data (to be sent down a telephone wire), also converts analogue data to digital data. Allows several simultaneous wireless connections to take place without interfering with each other. Connects to public infrastructure (cable optic fibre etc.) and supplies a standard Ethernet output which allows connection to a router and internet connection.

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10
Q

WLAN

A

Wireless LAN (local area network)

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11
Q

(W)AP

A

(Wireless) Access Point
Access point which allows a device to access a LAN without a wired connection

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12
Q

PAN

A

Network that is centred around a person/their workspace

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13
Q

Client server

A

Network that uses separate dedicated servers and specific client workstations, all client computers are connected to the dedicated servers

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14
Q

Spread spectrum technology

A

Wide and radio frequency with a range of 30 to 50 metres

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15
Q

Node

A

Device connected to a network (can be computer, storage device or peripheral device)

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16
Q

Peer-to-peer

A

Network in which each node can share its files with all the other nodes. Each node has its own data and there is no central server

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17
Q

Thin client

A

Device that needs access to the internet for it to work + depends a more powerful computer for processing

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18
Q

Thin client

A

Device that needs access to the internet for it work + depends on a more powerful computer for processing

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19
Q

Thick client

A

Device which can work both offline and online + is able to do some processing even if not connected to a network/internet

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20
Q

Bus network topology

A

Network using single central cable in which all devices are connected to this cable so data can only travel in one direction and only one device is allowed to transmit at a time

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21
Q

Packet

A

Message/data sent over a network from node to node (includes the address of the node sending the packet, address of recipient and actual data)

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22
Q

Star network topology

A

Network that uses a central hub/switch with all devices connected to it so that all data packets are directed through the hub/switch

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23
Q

Mesh network topology

A

Interlinked computers/devices which use routing logic so data packets are sent from sending stations to receiving stations via the shortest route

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24
Q

Hybrid network

A

Network made up of a combination of other network topologies

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25
Q

Cloud storage

A

Method of data storage where data is stored on off-site servers

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26
Q

Data redundancy

A

Situation in which the same data is stored on several devices in case of maintenance or repair

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27
Q

Wi-Fi

A

Wireless connectivity that uses radio waves, microwaves. Implements IEEE 802.11 protocols

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28
Q

Bluetooth

A

Wireless connectivity that uses radio waves in the 2.45GHz frequency band

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29
Q

Spread spectrum frequency hopping

A

Method of transmitting radio signals in which a device picks one of 79 channels at random, if in use it randomly picks another. Has a range up to 100 metres

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30
Q

WPAN

A

Wireless Personal Area Network
Local wireless network which connects devices in very close proximity (laptop, phone, home devices etc)

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31
Q

Twisted pair cable

A

Cable in which 2 wires of a single circuit are twisted together, several of these pairs make up a single cable, most common cable type in LANs. Lowest data transfer rate and suffers from external interference but is the cheapest option

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32
Q

Coaxial cable

A

Cable made up of central copper core, insulation, copper mesh and outer insulation. Most commonly used in MANs + by television companies. Higher cost but better data transfer rate (80x better capacity than twisted pair) and less affected by external interference. Greatest signal attenuation. Best anti-jamming capabilities

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33
Q

Fibre optic cable

A

Cable made up of glass fibre wires which uses pulses of light rather than electricity to transmit data. Most commonly used over long distances. Best data transfer rate, smallest signal attenuation, highest cost. 26 000 times the transmission capacity of twisted pair cables

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34
Q

Gateway

A

Device that connects LANs which use different protocols

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35
Q

Repeater

A

Device used to boost a signal on both wired(analogue/copper and digital/fibre optic) and wireless networks (prevents dead spots in WiFi zone and are termed non-logical devices because they boost ALL detected signals)

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36
Q

Repeating Hubs

A

Network devices which are a hybrid of hub and repeater unit

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37
Q

Bridge

A

Device that connect LANs using the same protocols can be wired or wireless

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38
Q

Softmodem

A

Software modem
Software based modem that uses minimal hardware

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39
Q

NIC

A

Network Interface Card
Allow devices to connect to the internet (associated with a MAC address set at the factory)

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40
Q

WNIC

A

Wireless Network Interface Cards

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41
Q

Ethernet

A

Protocol IEEE.802.3 used by many wired LANs

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42
Q

Conflict

A

Situation in which 2 devices have the same IP address

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43
Q

Broadcast

A

Communication where pieces of data are sent from sender to receiver

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44
Q

Collision

A

Situation where 2 messages/data from different sources are trying to transmit along the same data channel

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45
Q

CSMA/CD

A

Carrier Sense Multiple Access with Collision Detection
Method used to detect collisions and resolve the issue
When a frame is sent it causes a voltage change on the Ethernet cable, when a collision is detected a node stops transmitting a frame and transmits a ‘jam’ signal and waits for a random time interval before resending the frame

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46
Q

Bit streaming

A

Contiguous sequence of digital bits sent over a network/internet

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47
Q

Buffering

A

Store which temporarily holds data

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48
Q

Bit rate

A

Number of buts per second that can be transmitted over a network. Measure of the data transfer rate over a digital telecoms network

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49
Q

On demand (bit streaming)

A

System that allows users to stream video or music files from a central server as + when required without having to save the files on their own computer/tablet/phone

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50
Q

Real time (bit streaming)

A

System in which an event is captured by camera + microphone connected to a computer and sent to a server where the data is encoded. User can access data live

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51
Q

WAN vs the internet

A

Internet is a vast number of decentralised networks+computers which hav4 a common point of access so any one with internet access can connect to computers on these networks
WAN required passwords or user IDs to access it

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52
Q

Benefits of networking computers and devices (7)

A

Devices can be shared (reducing costs)
Licences to run software on networks are often far cheaper than for an equivalent no. Of stand alone computers
Users can share files and data
Access to reliable data that comes from a central source eg. file server
Data files can be backed up centrally at the end of each day
Users can communicate using email and instant messaging
A network manager can oversee the network and apply access rights to certain files/restrict access to external networks

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53
Q

Drawbacks of networking computers and devices (4)

A

Cabling + services are expensive
Managing a large network is complex and difficult
Breakdown of devices can affect the whole network
Malware + hacking can affect entire networks (firewalls help)

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54
Q

Hardware infrastructure of networked computers (5)

A

LAN cards
Routers
Switches
Wireless routers
Cabling

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55
Q

Software infrastructure of networked computers (3)

A

Operation + management of the network
Operation of firewalls
Security applications/utilities

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56
Q

Services of networked computers (4)

A

DSL (optic fibre)
Satellite communication channels
Wireless protocols
IP addressing

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57
Q

Categories of networks (2)

A

Public
Private

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58
Q

Private networks

A

Networks owned by a single company or organisation. Often LANs/intranets with restricted user access. Companies responsible for purchase of own equipment and software, maintenance of network + hiring and training of staff

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59
Q

Public networks

A

Networks Owned by a communications carrier company used by many orginisations, there are no specific password requirements but sub-networks may be under security management

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60
Q

Describe function of LANs

A

Consists of a number of computers + devices connected to hubs/switches, one of which is connected to a router and/or modem to allow the LAN to connect to the internet/become part of a WAN

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61
Q

Function of WAPs

A

Wireless access points
Connected to the wired network at fixed locations, commercial LANs (because of limited range) need several WAPs to permit uninterrupted wireless communications. Use spread spectrum technology(Wideband radio frequency) or infrared (short range+easily blocked)
Receives and transmits data between the WLAN and the wired network structure

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62
Q

How end users access the WLAN

A

Through wireless LAN adapters which are built into the devices/as a plug in module

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63
Q

Function of WANs (3)

A

Wide Area Networks
Used when computers/networks are situated far from each other. Formed by joining a number of LANs using a router or a modem.
Make use of public communications network or dedicated/leased lines (less expensive and more secure)
Consists of several end systems and intermediate systems

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64
Q

Guide to decide the size of a network (4)

A

PAN - 1m to 10m (home system)
LAN - 10m to 1000m
MAN - 1km to 100km
WAN - 100km to 1000+km

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65
Q

Types of networking models (2)

A

Client server
Peer to peer

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66
Q

Client server models (10)

A

Uses separate dedicated servers + specific client workstations
Users able to access most of the files stored on dedicated servers
Server dictates which users are able to access which files
Allows installation of software onto a clients computer
Uses central security databases (control access to shared resources)
Logged in users will only have access to resources assigned to them by the network administrator
Can be as large as you want and easy to scale up
Central server looks after storing, delivery and sending of emails
Offers the most stable system (nightly backup restores deleted resources)
Can become bottlenecked if there are several client requests simultaneously

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67
Q

Most important part of client-server vs peer-to-peer model

A

Client server: sharing of data
Peerto-peer: connectivity

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68
Q

Responsibilities of a file server in client-server model (3)

A

Central storage + management of files
Allowing users to share info without the need for offline devices (memory sticks)
Allowing any computer to be configured as the host machine and act as the file server

69
Q

Why would you use a client-server model (4)

A

Company/user has a large user-base
Access to network needs to be properly controlled
Need for good network security
Company requires data to be free from accidental loss (needs to be backed up at a central location)

70
Q

Example of client server model
Example of peer-to-peer model

A

Amazon
Small business where there is frequent user interaction

71
Q

What each node joining the peer-to-peer network allows (5)

A

Provision of services to all other network users
Other users on the network to simply access data from another node
Communication with peers connected to the network
Peers to be both consumers and suppliers (client server keeps them separate)
Peers to participate as equals on the network

72
Q

Function of peer-to-peer

A

Does not have a central server(thus meaning there is no requirement to authenticate users), each of the nodes on the network can share its files with all the other nodes and each of the nodes will have its own data.
Used where no more than 10 nodes are required (leads to performance + management issues)

73
Q

Security of peer-to-peer

A

Little since there is no central security system, so it is impossible to know who is authorised to share certain data. Users can create their own network node share point as the only real security aspect, but there are no real authentication procedures

74
Q

When would peer-to-peer be used (3)

A

Network of users is fairly small
No need for robust security
Require workstation-based applications rather than server-based

75
Q

What client server model offers (2)

A

Thin clients and thick clients

76
Q

Pros of thick clients (2)

A

More robust (device can carry out processing even when not connected to server)
Clients have more control (can store their own programs + data/files

77
Q

Cons of thick clients (3)

A

Less secure (relies on clients to keep their data secure)
Each client needs to update data+software individually
Data integrity issues, many clients access the same data leading to inconsistencies

78
Q

Pros of thin clients (3)

A

Less expensive to expand
All devices linked to a server (data updates + new software installation done centrally)
Server can offer protection against hacking + malware

79
Q

Cons of thin clients (2)

A

High reliance on the server (if it goes down/there is a link break devices cannot work)
Start up costs are generally higher than for thick clients

80
Q

Ways to connect computers to make complex networks (4)

A

Bus networks
Star networks
Mesh networks
Hybrid networks

81
Q

Thin client vs thick clients software (4 for each)

A

Always reliefs on connection to remote server/computer - can run some features when not connected

Requires few local resources (eg. SSD,RAM) - Relies heavily on local resources

Relies on a fast, stable network connection - more tolerant of a slow network connection

Data stored on a remote server/computer - can store data on local resources (HDD/SDD)

82
Q

Disadvantages of bus network topology (3)

A

If main cable fails the whole network goes down
The performance of the network deteriorates under heavy loading
Network is not secure since each packet passes through every node

83
Q

Advantages of bus network topology (2)

A

Network continues to function if a node fails
Easy to increase size of the network by adding additional nodes

84
Q

Suitability of bus networks

A

Situations with a small number of devices with light traffic occurring (small company/office environment)

85
Q

Function of bus networks

A

PEER TO PEER
Uses single cable to connect all computers + devices. Data can only travel in 1 direction so if data is being sent between devices other devices cannot. Requires terminators at each end to prevent signal reflection. Each node looks at each packet, determines if the address of recipient matches the node address, if not it is ignored.

86
Q

Disadvantages of a star network (2)

A

High installation costs
Of central hub/switch fails, whole network goes down

87
Q

Advantages of star network (4)

A

Reduced data collisions
More secure network (security methods can be applied to central node, packets only travel to nodes with correct address)
Easy to improve by installing an upgraded hub
If one of the connections is broken it only affects one of the nodes

88
Q

Suitability of star networks

A

Evolving networks where devices are frequently added or removed/apllication where there is heavy data traffic

89
Q

Function of star networks

A

CLIENT SERVER
Each device is connected to the central hub/switch, through with data is directed. Each device has its own dedicated connection and any type of network cable can be used.
If hub: packets sent to every device on network (accepted/ignored depending on address)
If switch: packets only sent to nodes where address matches the recipient address in the packet

90
Q

Examples of mesh network topology (4)

A

Internet and WANs/MANs
Medical monitoring of patients in a hospital
Electronics interconnectivity
Modern vehicles

91
Q

Function of mesh networks

A

PEER TO PEER
2 types: routing and flooding
Routing: works by giving nodes routing logic (act as routers) so data is directed via the shortest route to its destination and can be rerouted
Flooding: sends data via all nodes using no routing logic (leads to unnecessary loading on the network)

92
Q

Disadvantages of mesh networks (2)

A

Large amount of cabling needed (expensive+time consuming)
Set up + maintenance is difficult + complex

93
Q

Advantages of mesh networks (4)

A

Easy to identify where faults on the network have occurred
Broken links do not affect other nodules
Good privacy + security (packets travel along dedicated routes)
Relatively easy to expand

94
Q

Disadvantage of hybrid networks

A

Can be very complex to install, configure and maintain

95
Q

Advantages of hybrid networks (3)

A

Can handle large volumes of traffic
Easy to identify where a network fault has occurred
Very well suited to the creation of larger networks

96
Q

Systems of cloud computing (3)

A

Public
Private
Hybrid

97
Q

Public cloud

A

Storage environment where the customers/client and cloud storage provider are different companies

98
Q

Private cloud

A

Storage provided by a dedicated environment behind a company firewall. Customer/client and cloud storage provider are integrated + operate as a single entity

99
Q

Hybrid cloud

A

Combination of private and public clouds, some data resides in the private cloud, less sensitive/less commercial data can be accessed from a public cloud storage provider

100
Q

Pros of cloud storage (5)

A

Files can be accessed anytime from any device anywhere is internet access is available
No need to carry an external storage device/use the same computer to store information
Provides a remote back-up of data (aids data loss and disaster recovery)
Recovers data if a customer/client has a hard disk/back-up device failure
Offers almost unlimited storage capacity

101
Q

Cons of cloud storage (4)

A

Problems accessing/downloading files with a slow/unstable internet connection
Costs high if large storage capacity is required
Expensive to pay for high down/upload data transfer limits with internet service provider
Potential failure of cloud storage company (loss of all back-up data)

102
Q

Data security concerns with cloud storage (3)

A

Physical security by the building where the data is housed
Service providers resistance to natural disasters/powercuts
Safeguards regarding personnel who work for the cloud service company

103
Q

Areas covered by cloud (5)

A

Storage
Databases
Networking
Software
Analytical services using the internet

104
Q

Cloud software

A
105
Q

Cloud software

A

Allows software applications to be delivered on demand. The provider will manage and maintain the applications for a monthly fee. The software is fully tested and does not need to reside on the users device, but the user can still use the software if the internet is lost, the data will then be stored in the local device and uploaded when the connection returns

106
Q

When is Bluetooth useful (3)

A

Transferring data between 2 devices which are less than 30 metres apart
The speed of data transmission is not critical
Using low bandwidth applications

107
Q

Bandwidth of radio waves, microwaves and infrared

A

Infrared>microwaves>radio waves

108
Q

Penetration of radio waves, microwaves and infrared

A

Radio waves>microwaves>infrared

109
Q

Attenuation of radio waves, microwaves and infrared

A

Radio>microwaves>infrared

110
Q

Penetration

A

Ability of the electromagnetic radiation to pass through different media

111
Q

Attenuation

A

Reduction in amplitude of a signal (infrared is low because it can be affected by rain)

112
Q

Satellite technology

A

Curvature of the earth prevents electromagnetic waves from carrying signals globally, so signals are beamed from antenna A to a satellite orbiting earth, the signal is then boosted by the satellite and is beamed back to earth and picked up by antenna B

113
Q

Communication between satellite and antennae

A

Carried out by radio waves / micro frequencies. Different bands are used to prevent signal interference + allow networks across the earth to communicate

114
Q

Types of cables in wired networks (3)

A

Twisted pair cables
Coaxial cables
Fibre optic cables

115
Q

Types of twisted pair cables (2)

A

Shielded (commercial, contains thin metal foil jacket to cancel out external interference)
Unshielded (residential)

116
Q

Types of fibre-optic cables (2)

A

-Single mode (single mode light source, smaller central core, less reflection along the cable so faster and further data travel so best for telecommunications and CATV)
-Multi-mode (multi-mode light source, construction causes higher light reflections in core, so work best over short distances, best for LAN)

117
Q

Pros of bitcoin streaming (5)

A

No need to wait for a whole video/music file to download before watching/listening
No need to store large files on your device
Allows video + music files to be played on demand
No need for any specialist hardware
Affords piracy protection (more difficult to copy streamed files)

118
Q

Cons of bit-streaming (5)

A

Can’t stream video/music files if broadband connection is lost
Video/music files paused streaming to catch up (insufficient buffer capacity/slow broadband connection)
Uses a lot of bandwidth
Security risks of downloading from the internet
Copyright issues

119
Q

How on demand bit streaming works (5)

A

Digital files stored on server converted to a bit streaming format
Link to encoded to video/music file is placed on the web server to be downloaded
User clicks on the link and the file is downloaded in a contiguous bit stream
Streamed video/music is broadcast to the user as and when required
Possible to pause rewind and fast forward if required

120
Q

How real time bit streaming works

A

Event is captured by camera and microphone and is sent to a computer
Video signal is converted to a streaming media file
Encoded file is uploaded from the computer to the dedicated video streaming server
Server sends the encoded live video to the users device
Not possible to pause, rewind or fast forward since it is live

121
Q

Drawbacks of repeating hubs (repeaters) (2)

A

Only have 1 collision domain, so need jamming signals to manage collisions, but reduces network performance since it involves repeated broadcasts
Devices are referred to as unmanaged since they are unable to manage delivery paths + security in the network

122
Q

Role of routers (5)

A

Restricts broadcasts to a LAN
Act as a default gateway
Can perform protocol translation (lets wired communicate with WiFi by protocol conversion)
Can move data between networks
Can calculate best route to destination address

123
Q

Internet

A

Massive network of networks, made up of computers and other electronic devices; uses TCP/Ip communication protocols

124
Q

WWW

A

World Wide Web
Collection of multimedia web-pages stored on a website which uses the internet to access information from servers and other computers. Http(s) protocols are written using HTML, URLs specify the location of all web pages, web resources are accessed by web browsers.

125
Q

HTML

A

Hypertext Mark-up Language
Used to design web-pages + to write http(s) protocols

126
Q

URL

A

Uniform Resource Locator
Specifies location of a web page

127
Q

Web browser

A

Software that connects to DNS to locate IP addresses; interprets web pages sent to a users computer so that documents and multimedia can be read or watched/listened to

128
Q

ISP

A

Internet Service provider
Company which allows a user to connect to the internet, usually charge a monthly fee for the service they provide

129
Q

PSTN

A

Public Switched Telephone Network
Network used by traditional telephones when making calls/sending faxes

130
Q

VoIP

A

Converts voice and webcam images into digital packages to be sent over the internet
Carries out file compression to reduce the amount of data being transmitted

131
Q

IP

A

Internet protocol
Uses IPv4 or IPv6 to give addresses to devices connected to the Internet

132
Q

IPv4

A

IP address format which uses 32 bits giving 2*32 possible addresses
32 bits are split into 4 bits of 8 (range of 0-255)

133
Q

CIDR

A

Classless internet-domain routing
Increases IPv4 flexibility by adding a suffix to the IP address eg. 200.21.100.6/18

134
Q

IPv6

A

Newer IP address format which uses 128 bits (hex)

135
Q

Zero compression

A

Way of reducing the length of an IPv6 address by replacing groups of zeroes by a double colon (::); can only be applied once to avoid ambiguity

136
Q

Sub-netting

A

Practice of dividing networks into 2 or more sub-networks, reduces network traffic and hides the complexity of the overall network. Splits the HostID

137
Q

Private IP address

A

IP address reserved for internal network use behind a router

138
Q

Public IP address

A

IP address allocated by the user’s ISP to identify the location of their device on the Internet

139
Q

DNS

A

Domain Name Server/System
Gives domain names for Internet hosts and is a system for finding IP addresses of a domain name
Eliminates the need for the user to memorise IP addresses

140
Q

JavaScript

A

Object-oriented programming language used mainly on the web to enhance HTML pages

141
Q

PHP

A

Hypertext processor
HTML embedded scripting language used to write web-pages

142
Q

Differences between the internet and the worldwide web (8)

A

Internet:
-massive network of networks made up of various electronic devices
-stands for interconnected network
-makes use of transmission control protocol(TCP)/Internet protocols (IP)
Www:
-collection of multimedia web pages and other documents stored on websites
-http(s) protocols written using HTML
-URLs specify location of all web pages
-www uses internet to access information from servers and other computers

143
Q

Requirements for connecting to the internet (5)

A

Device
Telephone line/mobile phone network connection (may be wireless)
Router
ISP
Web browser

144
Q

What happens when using the internet to make a phone call

A

Users voice is converted to digital packages using Voice over Internet Protocol (VoIP)

145
Q

Phone calls using PSTN

A

Public switched telephone network
Uses a standard telephone connected to a phone line which is always open and not terminated until the receivers are replaced by both parties. It even remains active during power cuts as they have their own power source. Modern digitised systems use fibre optic cables meanwhile existing phone lines use circuit switching

146
Q

Phone calls using the Internet

A

Use either an Internet phone or microphone and speakers (and webcam for video calls)
Connection is only live while data is being transmitted
VoIP converts sound to digital packages which can be sent over the internet using packet switching, data is routed through thousands of possible pathways. The data is split into packages with each packet containing the sender and receivers address and order number. The sending computer sends data to router which sends packets to another router and so on until they arrive and are reassembled

147
Q

Phone calls using cellular networks and satellites

A

Done by mobile phones which act as the ISPs since they contain communication software which allows the, to access the telephone network and make an internet connection
Satellites are used for network communications that cover large distances, due to the curve of the earth, the higher the satellite orbit the more coverage it can give

148
Q

GEO

A

Geostationary orbit
Provides long distance telephone and computer network communications
35800 km
24 hour orbital period

149
Q

GEO

A

Geostationary orbit
35800 km
24 hours

150
Q

MEO

A

Medium Earth Orbit
GPS systems
5000-12000km
2-12 hour orbital period

151
Q

LEO

A

Low Earth Orbit
Mobile phone networks
500-1200km
80 minutes-2 hour orbital period

152
Q

Advantages of satellites

A

Always give complete coverage
Don’t suffer from signal attenuation to the same extent as underground/sea cables
Easier to isolate and resolve faults that undersea cables

153
Q

Operation of broadband routers

A

Sit behind a firewall which protects the computers on the network.
Main function is to transmit the Internet and transmission protocols between 2 networks and allow private networks to be connected. Inspects data package sent to it, sends the packet to the appropriate switch (inspect IP) from which it will be delivered using the MAC address

154
Q

Routers features (4)

A

Forward packets of data from one network to another
Route traffic between networks
Join LANs to form WANs or connect LANs to the internet
Offer additional features such as dynamic routing (ability to forward data by different routes)

155
Q

WNIC modes (2)

A

Infrastructure mode - uses WAP (and hub/switch) to transfer all the data, all wireless devices must use the same security and authentication techniques

Ad hoc mode - does not have access to WAPs, possible for devices to interface with each other directly

156
Q

Parts of a network using Ethernet (3)

A

Node (any device on the LAN)
Medium (path used by LAN devices such as Ethernet cable)
Frame (data is transmitted in frames made up of source and destination address (often MAC))

157
Q

What public IP addresses are used by (3)

A

DNS servers
Network routers
Directly-controlled computers

158
Q

Web browsers

A

Software that allow users to access using URLs and display web pages on their screens by interpreting HTML sent from websites and displaying the results.

159
Q

Web browsers

A

Software that allow users to access using URLs and display web pages on their screens by interpreting HTML sent from websites and displaying the results.

160
Q

Format of URL

A

protocol://website address/path/filename
Protocol is usually http/https

161
Q

Content of website address (4)

A

Domain host (www)
Domain name (name of website)
Domain type (.com, .org etc.)
Country code (.uk, .za etc.)

162
Q

DNS process (5)

A

-User opens browser, types in URL and the browser asks the DNS server(1) for the IP address of the website
-DNS server(1) can’t find it in its database or it’s cache and sends request to DNS server(2)
-DNS server(2) finds the URL and can map it to an IP address which is then sent back to the DNS server(1) which puts the IP address and associated URL into its cache/database
-IP address is then sent back to the user’s computer
-Computer sets up a communication with the server and downloads required pages, the browser interprets HTML and displays the information on the Users screen

163
Q

Network class A
Give IPv4 range, no. of netID bits, no. of hostID bits, types of network

A

0.0.0.0 to 127.255.255.255
8
24
Very large

164
Q

Network class B
Give IPv4 range, no. of netID bits, no. of hostID bits, types of network

A

128.0.0.0 to 191.255.255.255
16
16
Medium size

165
Q

Network class D
Give IPv4 range, no. of netID bits, no. of hostID bits, types of network

A

-
Multi-cast

166
Q

Network class E
Give IPv4 range, no. of netID bits, no. of hostID bits, types of network

A

-
Experimental

167
Q

Network class C
Give IPv4 range, no. of netID bits, no. of hostID bits, types of network

A

192.0.0.0 to 223.255.255.255
24
8
Small networks

168
Q

Benefits of IPv6 (4)

A

No need for NATs (Network Address Translations)
Removes risk of private IP address collisions
Has built in authentication
Allows for more efficient routing

AS Computer Science (5 decks)

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