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Computer Science > Unit 3 - Network connections and protocols > Flashcards

Unit 3 - Network connections and protocols Flashcards

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1
Q

What is a wide area network (WAN)?

The Internet and WANs

A

The computers are geographically distanced more than a mile apart and uses third party hardware

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2
Q

What is local area network (LAN)?

The Internet and WANs

A

The computers are geographically close and less than a mile apart and uses internal hardware

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3
Q

What are differences between a LAN and WAN?

The Internet and WANs

A

WAN is over a large geographical area, a LAN is over a small geographical area.
WAN uses external hardware / infrastructure / cables,
LAN has its own infrastructure / cables / network / hardware due to distance.

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4
Q

What is an IP address?

The Internet and WANs

A

An IP address is a unique number given to a device connected to the internet.

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5
Q

How is packet switching used to send data?

The Internet and WANs

A

Data is split into packets. Each packet has a fixed size and a header that includes packet number/destination. Packets are sent individually in different routes. The receiving computer waits for all
packets then puts them back in order. Sends requests for missing packets which are resent.

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6
Q

What is Domain name system (DNS)?

The Internet and WANs

A

The Domain Name System is made up of domain names which is used to refer to an IP address.

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7
Q

How is a website loaded when the URL is typed in?

The Internet and WANs

A

The website is hosted on a webserver which has an IP
address. Browser sends URL to DNS which is linked to a IP. DNS finds IP, and send it back to the
browser. Which sends request to webserver. processes request for the website and sends the
webpage to the user.
if DNS cannot find the IP it passes request to higher DNS, if not found return error.

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8
Q

What is a network interface card (NIC)?

The Internet and WANs

A

A network card which is built into every device

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9
Q

What is a MAC address?

The Internet and WANs

A

MAC address is assigned to each Network Interface Card (NIC) by the manufacturer. Every networked device in the world has a unique MAC address.

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10
Q

What is the role of the MAC address?

The Internet and WANs

A

The actual geographical location of a networked device can be determined by its IP address. When you request a web page, each router along the way uses the MAC address of the next router to send the data packet on the next leg of its journey.

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11
Q

What are advantages of networks?

Local area networks

A
  • Computers can share resources such as printers
  • Files can be accessed through any computer in the network
  • Data is easy to back up as it is stored centrally on the server
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12
Q

What are disadvantages of networks?

Local area networks

A
  • Managing a large network is complicated
  • Data is easy to back up as it is stored centrally on the server
  • Viruses may be able to infiltrate the network and infect every computer
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13
Q

What are the 2 types of topologies?

Local area networks

A
  • star
  • mesh
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14
Q

What are the advantages of star topology?

Local area networks

A
  • Fast data transfer to the hub as each wire isn’t shared with other computers
  • If one cable fails the other computers are not affected
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15
Q

What are the disadvantages of star topology?

Local area networks

A
  • Requires additional hardware such as the central switch and network cables
  • If the central switch fails the whole network goes down
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16
Q

What are the advantages of mesh topology?

Local area networks

A
  • No single point of failure – it is resilient
  • Expansion and modification can be done without disrupting the network
  • Data can be transmitted from different devices simultaneously
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17
Q

What are the disadvantages of mesh topology?

Local area networks

A
  • Can involve redundant connections
  • Expensive to install cabling if using wired connections
  • Network maintenance and administration is difficult
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18
Q

What is the role of a wireless acccess point (WAP)?

Local area networks

A

connects wireless devices to a network.

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19
Q

What is the role of a router?

Local area networks

A
  • Looks at the destination of packets of data and sends them to the network that is closer towards their destination
  • A home router will route packets between the home LAN and the Internet
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20
Q

What is the role of a switch?

Local area networks

A
  • To connect the devices together
  • Receives data/packets/traffic
  • Direct/send data/packets/traffic only to its destination
  • Creates/generates a list of devicesconnected to it as it receives signals
  • Uses MAC addresses of devices connected to it
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21
Q

What is ethernet?

Local area networks

A

Ethernet is a family of protocols, which uses wired data transmission, within the TCP/IP stack. Ethernet can transmit data at 100GBs per second.

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22
Q

Why is ethernet standard?

Local area networks

A

Ethernet is used by all manufacturers, in
many devices, to allow compatibility with other
devices

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23
Q

What are some features of ethernet?

Local area networks

A
  • Ethernet has a high bandwidth
  • Ethernet has inbuilt security
  • Ethernet is a proven/reliable connection
  • Ethernet is low cost for purchase
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24
Q

What is transmission media?

Local area networks

A

Transmission media is the way that communication is sent through the network

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25
Q

How is media transmitted?

Local area networks

A

Ethernet is sent through twisted copper cables or fibre optic cables
Internet connections to UK houses are typically sent through copper cables or coaxial cables.
Fibre connections often only go as far as the local green cabinet

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26
Q

What is bluetooth?

Wireless networking

A

Bluetooth is a wireless method of connecting devices together over a short distance. It uses radio waves at 2.4 GHz

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27
Q

What does pairing bluetooth devices allow?

Wireless networking

A

A persistent link is made between the two devices
A device can ask for a passkey in order to pair to it – this gives a layer of security like a password
Passkeys only need to be entered once and will be remembered by devices that are paired

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28
Q

How does wireless transmission work?

Wireless networking

A

Commonly uses radio waves for communication
Susceptible to interference from objects and other nearby electronic or radio devices

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29
Q

What is a wireless access point (WAP)?

Wireless networking

A

A wireless Access Point (AP) is a device that allows wireless devices to connect to a wired network using Wi-Fi. The AP usually connects to a router via a wired network

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30
Q

What are the 2 types of frequency?

Wireless networking

A
  • 2.4GHz
  • 5GHz
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31
Q

What is the advantage of using 2.4Ghz?

Wireless networking

A

Greater range and coverage

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32
Q

What is the disadvantage of using 2.4Ghz?

Wireless networking

A

More interference from other devices as this is a crowded frequency

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33
Q

What is the advantage of using 5Ghz?

Wireless networking

A

Less crowded space with 23 non-overlapping channels with higher data transmission rates

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34
Q

What is the disdvantage of using 5Ghz?

Wireless networking

A

Less able to penetrate through walls

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35
Q

What is data interception?

Wireless networking

A

Data that is transmitted over a network can be intercepted. Any intercepted data can be read and understood unless measures are taken to prevent it from being interpreted.

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36
Q

How can we prevent data from being intercepted?

Wireless networking

A

Via encryption

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37
Q

What is encryption?

Wireless networking

A

Encryption is the encoding of data so that it can no longer be easily understood

38
Q

Why should encryption be used?

Wireless networking

A
  • Data cannot be understood if intercepted. So that only authorised users can access the confidential material
  • To follow legislation/DPA
39
Q

What are the 2 types of encryption?

Wireless networking

A
  • Private key (Symmetric encryption)
  • Public key (Asymmetric encryption)
40
Q

What is symmetric encryption?

Wireless networking

A
  • A single key is used to encrypt and decrypt a message and must be given to the recipient of your message to decrypt the data
41
Q

What is asymmetric encryption?

Wireless networking

A

Two keys are used - one (public key) to encrypt and the other (private key) to decrypt data. This is more secure as it means that you never have to send or reveal your decryption key.

42
Q

What is a client server model

Client-server networks

A

The server is a powerful computer which provides services or resources required by any of the clients
A client is a computer or device which requests the services or resources provided by the server.

43
Q

What are the benefits of using wireless connection?

A
  • Allows more devices to connect
  • Easy to connect devices and to setup wireless connections
  • Home is likely small area so short distance wireless is sufficient
  • Devices can move around and can connect from anywhere in the house
  • Cheaper to purchase/install/setup for new devices because no additional/fewer wires are needed
  • Fewer trip hazards from trailing wires
  • More compatible
44
Q

What are drawbacks of using wireless connections?

A
  • Prone to interference
  • Limited range of signal
  • Slower rate of transmission / bandwidth
  • Increased risk of security concerns
  • Less stable connection
  • Higher chance of collisions
45
Q

What are the benefits of wired connection?

A
46
Q

What are the drawbacks of wired connection?

A
47
Q

What is the role of the client computer?

A

The client sends requests to the server
Waits for a reply
Receives the reply

48
Q

What is the role of the server computer?

A

The server waits for requests from a client
Performs any processing required to fulfil the request
The requested data is sent back to the client

49
Q

What is the role of the client computer in a website?

A
  • Sends the files to the web server
  • Performs the user’s actions and sends the results to the web server
  • Sends a request to the web server
50
Q

What is the role of the server computer in a website?

A
  • Web server receives a request
  • Web server executes/responds to the request
  • Web server returns confirmation/error of the processing
51
Q

What are the advantages of client-server model?

A

With file servers, just one file server needs to be backed up and files can be accessed from any computer
Email servers provide a central place for email that is then accessed from different devices
One print server can manage all files to be printed. This allows one printer to be shared by many computers

52
Q

What is peer-to-peer networking?

A
  • Suitable for a small companies with fewer computers
  • No central server controls files or security
  • All computers can easily see files on all other computers
  • All computers can communicate with each other without going through a server
53
Q

What are the advantages of a P2P network?

A
  • Easier to set up – computers can simply be cabled together
  • No need for dedicated server equipment
  • Individual computers can share a printer, router, modem and other hardware
  • Users can communicate directly with each other and share each others’ files
54
Q

What are the disadvantages of a P2P network?

A
  • Viruses and malware are more easily transferred over this type of network as there is no central firewall
  • Data recovery and backup is not done centrally, so each computer has to have its own backup system
  • Files are not centrally organised, but stored on individual computers and may be hard to locate if the computer’s owner does not have a logical filing and naming system
  • If a computer is switched off, data on that machine cannot be retrieved from other machines
55
Q

What is hosting?

A

Web hosting is a service offered by companies that will host web pages and files for websites. The web hosts will often provide database servers. Companies that provide more general hosting, such as backup servers, are known as hosting service providers

56
Q

What are advantages of using web hosts?

A
  • Web hosts have far more bandwidth – so they can serve more users
  • Web hosts are able to monitor their equipment 24 hours a day
  • Web hosts will backup web sites remotely
57
Q

What is the cloud?

A

refers to services that are delivered over the Internet. It enables users connected to any Internet-enabled computer to access these services

58
Q

What are advantages of using cloud?

A
  • enables user to access their data from more places/devices;
  • enables user to more easily share data with others
  • increases the amount of potential storage available;
  • reduced cost of computing devices for users as no need for as much built-in secondary storage
  • cloud storage is automatically backed up by the host;
59
Q

What are disadvantages of using cloud?

A
  • Increased security risks;
  • Relies on access to high-bandwidth network connection; Could potentially cost more due to ongoing costs
  • Increased chance of others accessing personal data
  • If the Internet connection is lost, often the service becomes unusable
  • If the Internet connection is lost, often the service
    becomes unusable
60
Q

What are advantages of copper cables?

A
  • tried and trusted technology
  • relatively inexpensive

uses electricity

61
Q

What are disadvantages of copper cables?

A
  • signal affected by electric and magnetic fields
  • low bandwidth
  • heavy cables
62
Q

What are advantages of fibre optics?

A

very fast data transmission
low loss of signal over distance
not affected by magnetic or electric fields
require very little power
more difficult to ‘tap into’ than copper cables

uses light

63
Q

What are disadvantages of fibre optics?

A
  • high investment cost
  • need for expensive optical transmitters and receivers
64
Q

What are the advantages of wireless transmission?

A
  • no need for trailing wires (safer)
  • allows devices to be used anywhere provided there is a signal
  • easier to add devices to a network

uses radio waves

65
Q

What are the disadvantages of wireless transmission?

A
  • data transmission rate less than wired systems
  • signal can be blocked by objects or walls
  • increased security issues
66
Q

How can wifi frequency affect the performance of a network?

A

5GHz frequency has can transfer data faster. 5GHz frequency has a shorter range so access may be limited

67
Q

How can intereference affect the performance of a network?

A

Causes errors which means signals need retransmitting which makes more traffic. Objects may
block the signal

68
Q

How can number of users affect the performance of a network?

A

more traffic means the same bandwidth is split / more collisions

69
Q

How can type of network traffic affect the performance of a network?

A

transmitting videos/large files will take up more bandwidth than text files

70
Q

How can bandwith affect the performance of a network?

A
71
Q

What is the HTTP protocol used for?

A

HTTP is used for accessing and receiving web pages via the Internet. The protocol requests a web page from the web server.

72
Q

What is the HTTPS protocol used for?

A

HTTPS encrypts the information so that it cannot be understood by an eavesdropper

73
Q

What is the FTP protocol used for?

A

FTP is used for sending or retrieving files to or from a FTP server

74
Q

What is the SMTP protocol used for?

A

email protocol used for sending email

75
Q

What is the POP/IMAP protocol used for?

A

These email retrieval protocols fetch message data and attachments from your remote mail server

76
Q

How does POP work?

A

POP will download every new message to your local device and with them no longer being available on the
server

77
Q

How does IMAP work?

A

IMAP will leave the messages on a server. They can be accessed by multiple devices and they only are removed if the user deletes them.

78
Q

How is an email sent?

A

Email software sends the email to the SMTP server used by the company or individual. The mail server then relays the message through various other servers known as mail relays. Finally, the email arrives at the
destination mail server.When it reaches the destination mail server it is stored. The user’s computer uses POP or IMAP to access the email.

79
Q

What is the TCP/IP protocol used for?

A

Transferring data packets over the internet

80
Q

What does the TCP layer do?

A
  • Breaks up messages sent over the Internet into packets
  • Reassembles the packets at the other end
  • Detects errors
  • Resends lost messages
81
Q

What does the IP layer do?

A

Routes the individual packets from one IP address to another

82
Q

What are the 4 layers?

A

Application layer
Transport layer
Internet layer
Link layer

83
Q

What happens in the application layer?

A

Applications such as email clients and web browsers create data to send in this layer

84
Q

What protocols operate in application layer?

A
  • HTTP/HTTPS for browsing
  • FTP for file transfer software
  • SMTP for sending email
  • POP/IMAP to recieve email
85
Q

What happens in the transport layer?

A

The Transport layer creates the connection between two computers, or ‘hosts’. Data is then divided up into packets and given a packet number. Packets are reassembled by the recipient’s Transport layer. Lost packets are resent

86
Q

Which protocol operates in the transport layer?

A

TCP

87
Q

What happens in the internet layer?

A

The Internet layer is responsible for routing packets

88
Q

Which protocol operates in the internet layer?

A

IP (and routers)

89
Q

What is the link layer?

A

Link layer includes physicala harware abd cables such as ethernet, and wifi

90
Q

How does recieving data work using layers?

A

The link layer removes the MAC address and passes packets up to the Internet laye, which removes the IP
addresses and passes packets up to the Transport layer. The Transport layer reassembles the packets and passes the data to the Application layer/ The Application layer uses the correct protocol to correctly display the data, web page or email for the user

91
Q

What are the advantages of layers?

A
  • A layer can be removed/changed without affecting any other layers
  • Each layer has its own purpose so it does not need to consider what the other layers do, so it can be programming individually
  • Individual protocols are each smaller/simpler to manage
  • Different layers can interface with different hardware providing interoperability between providers and systems
92
Q

What is a protocol?

A

A set of rules / standard for how computers should communicate

Computer Science (7 decks)

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