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GCSE Computing > 3.5 Fundamentals Of Computer Networks > Flashcards

3.5 Fundamentals Of Computer Networks Flashcards

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1
Q

Computer network definition:

A

Devices connected together that allow these devices to share information and resources

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2
Q

Benefits of compute networks:

A
  • sharing files is easier (network users can access files, work on them at same time, copy files between machines)
  • can share the same hardware (printers) between multiple devices
  • can install/update software on all computers at once (not one-by-one)
  • can communicate across a network cheaply & easily (email)
  • user accounts can be stored centrally (users can log in from any device on the network)
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3
Q

Risks of computer networks:

A
  • can be expensive to set up (often need lots of extra hardware)
  • can be vulnerable to hacking
  • malware can easily spread between networked computers
  • some dependent on 1+ servers, if servers go down it can be disruptive for people using network
  • large networks difficult to manage, may require employing a specialist to maintain them
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4
Q

Main types of computer network:

A
  • Personal Area Network (PAN)
  • Local Area Network (LAN)
  • Wide Area Network (WAN)
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5
Q

Personal Area Network (PAN)

A

= connects devices in a very short range
- normally centred around a single user
- often used to transmit between mobile/wearable devices
- use common wireless tech (Bluetooth) to connect devices
Bluetooth = strong but short range so ideal for connecting devices in same room
- handy as don’t require additional hardware (can create on the move)

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6
Q

Local Area Network (LAN)

A

= covers a small geographical area located on a single site

  • all hardware owned by organisation that uses it
  • can be wired (ethernet cables) or wireless (wi-fi)
  • often in businesses, schools, universities
  • many homes have it to connect various devices (PCs, tablets, printers, smart TV)
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7
Q

Wide Area Network (WAN)

A

= connects LANs in different geographical locations

  • organisations hire infrastructure from telecommunication companies, who own and manage WAN (as very expensive to set up)
  • so under collective/distributed ownership
  • may be connected using telephone lines (copper/fibre optic), satellite links, or radio links
  • internet = one big WAN
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8
Q

Switch:

A

Connects devices on a LAN

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8
Q

Router:

A

Transmits data between different networks different networks (mostly to connect to internet)

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9
Q

What is a Network Interface Card (NIC)

A

= piece of hardware inside a device, allows it to connect to networks
(For both wired and wireless connections)

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10
Q

What are local wireless networks called?

A

= WLANs (wireless LANs)

Wi-Fi = specific family of WLAN protocols

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11
Q

What is a WAP?

A

WAP = wireless access point device

Needed to set up wireless network, allows devices to connect

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13
Q

What do wireless networks use to transmit data?

A

Radio waves

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13
Q

Benefits of wireless networks (compared to wired networks):

A
  • convenient, device can automatically connect to network & move around while connected
  • can be cheaper & better for environment (don’t need wires)
  • very easy to add more users (don’t need to install extra wired/do a complex setup)
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14
Q

Risks of wireless networks (compared to wired networks):

A
  • generally less secure, access points usually visible to all devices (not just trusted ones) = can allow hackers to gain access
  • distance from WAP, interference from other wireless networks, physical obstructions = reduce signal strength, limit to how far network can reach
  • lower bandwidth & less reliable
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15
Q

List different cables used to connect devices on a wired network:

A
  • fibre optic cable
  • CAT 6/5e, twisted copper cable
  • coaxial cable
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16
Q

Twisted pair of copper wires (CAT 6/5e) cable:

A
  • common type of Ethernet cable
  • pair of copper wires twisted together to reduce internal interference
  • cheaper
  • decent bandwidth (used for LANs)
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18
Q

Coaxial cable

A
  • single copper wire surrounded by plastic layer for insulation & metallic mesh to provide shielding from outside interference
  • very cheap
  • low bandwidth
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19
Q

Fibre optic cable:

A
  • transmits data as light
  • high performance & expensive
  • don’t have interference
  • can transmit over very large distances at high bandwidth without loss of signal quality
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20
Q

network topology definition:

A

The layout of a network

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21
Q

List the common network topologies:

A
  • star topology

- bus topology

22
Q

Star topology:

A

= all devices are connected to a central switch or server that controls the network

  • central switch allows many devices to access server simultaneously
  • may be wired/wireless
23
Q

Pros of star topology:

A
  • if device fails/cable disconnects, rest of network is unaffected
  • simple to add more devices (each device connected to switch using separate cable)
  • better performance, data goes straight to central device so all devices transmit data at same time
  • fewer data collisions
24
Q

Cons of star topology:

A
  • in wired networks, every device needs cable to connect to central server/switch = expensive
  • central switch = expensive piece of hardware
  • is problem with switch/server, whole network affected
  • max no. of possible connections determined by switch, if more is needed, need to buy a new one
25
Q

Bus topology:

A

= use a single ‘backbone’ cable (bus) to connect to all devices
= 2 terminators places at ends of bus to stop data reflecting back along bus (reflected signals cause interference & potentially make network unusable)
- only wired networks

26
Q

Pros of bus topology:

A
  • network unaffected if device fails
  • aren’t dependant on a central switch working to keep network running
  • relatively cheap to set up, less wiring needed
  • hardware needed (bus cable,terminations) cheaper to buy & maintain than switches
27
Q

Cons of bus topology:

A
  • data collisions common, then data must be reset which slows network down
  • more devices added = more likely data collisions so unsuitable for large networks
  • devices must wait for bus to be available to send any data to avoid data collisions = slows network down
  • if bus cable breaks, splits network into separate parts which don’t have terminators at each end = lots of reflected signals, can shut down entire network
28
Q

Network protocol definition

A

A set of rules for how devices communicate and how data is transmitted across a network

  • how communication between 2 devices should start/end
  • how data should be organised
  • what devices should do if data goes missing
29
Q

List common network protocols:

A
  • Ethernet
  • Wi-Fi
  • TCP (Transmission control protocol)
  • UDP (User data gram protocol)
  • IP (Internet protocol)
  • HTTP (Hypertext Transfer Protocol)
  • HTTPS (Hypertext Transfer Protocol Secure)
  • FTP (File Transfer Protocol)
  • email protocols:
    - SMTP (Simple Mail Transfer Protocol)
    - IMAP (Internet Message Access Protocol)
30
Q

Purpose & use of Ethernet:

A

= family of protocols that operates on the link layer

  • handles transmission of data between devices on LANs
  • for wired connections
31
Q

Purpose & use of Wi-Fi:

A

= standard family of protocols for WLANs (link layer)

32
Q

TCP (Transmission Control Protocol)

A

= establishes connection between sending & receiving devices

  • then splits data into numbered packets (can be reassembled at destination)
  • communicates with receiving device to check all packets have been transferred correctly
  • sending device gets confirmation when transfer complete
33
Q

UDP (User Datagram Protocol)

A

= breaks down data into packets without numbering them
- unnumbered packets read by receiving device in order they arrive (may not be order sent)
- only sends each packet once, doesn’t check if they have been received
= saves time, don’t know if packets have gone missing in transit

34
Q

IP (internet protocol)

A

= establishes connections between routers & handing network traffic

  • IP address = unique number assigned to every device connected to IP network
  • directs data packets to destination using packet switching, each packet sent through series of routers which read packet’s IP address to decide which router to send packet to next
  • packet switching = efficient as many possible routes packet can take, packets reach receiving device quickly, even if traffic
35
Q

HTTP (Hyper Text Transfer Protocol)

A

= used by web browsers to access websites & communicate with web servers

36
Q

HTTPS (Hyper Text Transfer Protocol Secure)

A

= more secure version of HTTP, encrypts all info sent & received

37
Q

FTP (File Transfer Protocol)

A

= used to access, edit, move files between devices on a network

38
Q

IMAP (Internet Message Access Protocol)

A

= used to retrieve emails from a server

39
Q

SMTP (Simple Mail Transfer Protocol)

A

= Used to send emails & transfer mails between servers

40
Q

Need for network security?

A

They are vulnerable to attacks by criminals

Protects against damage, cyber attacks & unauthorised access

41
Q

Methods of network security:

A
  • authentication
  • encryption
  • firewall
  • MAC address filtering
42
Q

Authentication

A

= makes sure anyone trying to access network is who they say they are, prevents unauthorised people for accessing data from network

  • passwords
  • biometrics
  • email confirmation
  • CAPTCHA
43
Q

Encryption

A

= when data is translated into code which only someone with correct key can access (unauthorised users can’t read it), essential for sending data over a network securely

  • encrypted text = cipher text
  • non-encrypted text = plain text
44
Q

Firewall

A

= anti-malware software which examines all data entering & leaving a network & blocks any potential threats
- used to prevent unauthorised access to a companies network

45
Q

MAC address filtering

A

= checks unique identification (MAC address) of each device that tries to connect to network & only lets allowed devices to join network, blocks others
makes sure only people on a network are trusted users

46
Q

User access levels (authentication)

A

= control which parts of network different groups of users can access
- limits no. of people with access to important data, help to prevent attacks from within an organisation

47
Q

4 layer TCP/IP model: (protocols operating on that layer)

A
  • application layer(4) = HTTP, HTTPS, FTP, SMTP, IMAP
  • transport layer(3) = TCP, UDP
  • internet layer(2) = IP
  • link layer(1) = Wi-Fi, Ethernet
48
Q

Application layer

A

= provides networking services to applications

= where network applications (web browser, email programs) operate

49
Q

Transport layer

A

= sets up communications between 2 devices(hosts), splits data into packets & checks packets correctly sent/delivered
= hosts agree settings (language, size of packets)

50
Q

Internet layer

A

= adds IP addresses to data packets, directs packets between devices & handles traffic, used by routers
= routes packets across network

51
Q

Link layer

A

= passes data over physical network, responsible for how data is sent as electrical signals over cables, wireless & other hardware, interprets signals using device drivers
- where network hardware (NIC - Network Interface Card) & device drivers sit

GCSE Computing (8 decks)

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