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A Level Computer Science > 1.3.3 Networks > Flashcards

1.3.3 Networks Flashcards

1
Q

Define a network

A

Two or more computers connected together, to share information and resources

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2
Q

Define a LAN

A

Local Area Network:

A connection of devices

In a small geographical location

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3
Q

What are the advantages of a LAN?

A
  • Enables privacy from the outside world
  • Can control the access to data/programs
  • Can control the access to devices
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4
Q

What are the disadvantages of a LAN?

A
  • Requires some expertise to install and maintain
  • Can be costly for a larger LAN
  • Unauthorised access to data depends on personnel and their security measures
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5
Q

Describe the role of an NIC

A

Network Interface Card:

Converts data signals from a node into one that can be transferred over a network

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6
Q

Describe the role of a switch

A

Connects all the nodes together; intelligent so can send data packets only to their intended destination

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7
Q

Describe the role of a hub

A

Connects all the nodes together; not intelligent so data packets are transmitted across the whole network

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8
Q

Describe the role of a router

A

Manage data packets, enabling them to be sent between networks

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9
Q

Describe the role of a WAP

A

Wireless Access Point:

Allows nodes to connect to the network wirelessly

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10
Q

What is the difference of a client-server network over a peer-to-peer network?

A
  • A computer is designated as the server, rather than all having the same status
  • Server manages network traffic and data requirements, thus having less collisions and being faster
  • Larger networks have more servers, this can handle a greater network demand
  • Popular of companies, rather than home networks
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11
Q

Advantages and disadvantages of a bus network topology

A
  • Cheap, due to all nodes being connected to one cable
  • Data collisions slow the network - travels both ways
  • Whole network suffers from cable faults
  • Only useful over small areas
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12
Q

Advantages and disadvantages of a ring network topology

A
  • Cheap: only one cable
  • One-way data travel - no collisions
  • Whole network suffers from cable faults
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13
Q

Advantages and disadvantages of a star network topology

A
  • Other nodes are unaffected from a cable fault
  • Can be costly with large number of nodes
  • Network will slow with multiple nodes requesting data or software at the same time
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14
Q

Advantages and disadvantages of a mesh network topology

A
  • Every node is connected
  • Other routes are available to combat high network traffic or cable faults
  • Very expensive: large amounts of cabling required
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15
Q

What is the difference between a LAN and a WAN?

A

LAN: Located on one site, owner owns the network devices

WAN: Covers a large geographical area, devices can be provided by telecoms companies

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16
Q

Explain ‘Web Hosting’

A

A computer on a network: serves users of the internet as a host.

Websites are usually hosted on servers for people to access them (sometimes for a fee)

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17
Q

Explain ‘IP address’

A

Internet Protocol Address:

A unique number given to every computer on the internet.

Identifies the computer, may change each time a network is joined

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18
Q

Explain ‘ISP’

A

Internet Service Provider:

The company who provides you with an internet connection

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19
Q

Explain ‘URL’

A

Uniform Resource Locator:

The name for a web adress

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20
Q

Explain ‘DNS’

A

Domain Name System:

The system used to find the computer hosting the required website

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21
Q

Explain ‘the Cloud’

A

A network of servers hosted on the internet, offering a range of services for data

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22
Q

How does a DNS work?

A
  • The website’s URL is entered
  • The URL is sent to the ISP, where it is looked up in their DNS’s address book
  • The required IP address is returned to you, to communicate to the computer hosting the website
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23
Q

Advantages of the Cloud

A
  • Don’t need to buy and install software
  • Any connected device can access the service
  • No need to upgrade software
  • Collaborative documents can be formed
  • Work is saved automatically
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24
Q

Disadvantages of the Cloud

A
  • Sensitive data stored in other countries may be under different data laws
  • Can be less secure than local storage
  • Completely reliant upon the network/internet
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25
Q

What is the role of an internet registrar?

A
  • Holds the details of domains available for purchase
  • Registers company details
  • Resolves domain name disputes
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26
Q

How are files sent over the internet?

A

They are split into data packets before being transmitted

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27
Q

What are the components of a data packet?

A

Data

Error check

Packet header

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28
Q

Describe the Error check within a data packet

A

Includes a checksum number: a calculation for checking if all the data has arrived uncorrupted

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29
Q

Describe the Packet header within a data packet

A

Sequence number: for data packets to be put back together in the right order

Return address: when needed to notify the sender’s computer if the packet has been received or has been corrupted

Destination address: so the packet arrives in the correct location

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30
Q

Define a protocol

A

A set of rules for devices to follow

31
Q

Describe a MAC address

A

(Media Access Control) Hard-coded into each networked device, so data can be sent to the correct node’s NIC

32
Q

Describe the features of an IP address

A

Used so data on a WAN is sent to the correct network/node

Dynamic: changes whenever you connect to a network

33
Q

Describe TCP/IP

A
  • Transmission Control Protocol / Internet Protocol determines how data is sent over the internet
  • TCP: defines rules for splitting up packets, ensures data is split apart and put together the right way
  • IP: ensures data packets are directed towards their destination in the most appropriate way
34
Q

Describe ‘Packet Switching’

A
  • TCP splits a file in packets
  • IP directs packets through routers
  • Packet switching occurs by packets being directed to other routers on their journey
  • TCP reassembles the packets per their sequence number
35
Q

Describe ‘Circuit Switching’

A

When two devices are connected by a dedicated communication channel.

  • Data is sent in-order for no receiving delay
  • Wastes bandwidth as others cannot use the same channel
36
Q

Describe HTTP

A

Hyper Text Transfer Protocol:

Governs the way websites and web servers are accessed by web browsers

37
Q

Describe HTTPS

A

HTTP Secure:

Ensures all data being sent is encrypted

38
Q

Describe FTP

A

File Transfer Protocol:

Governs the way stored files are accessed from a server

39
Q

Describe POP

A

Post Office Protocol:

Governs how emails area accessed from a server

40
Q

Describe IMAP

A

Internet Message Access Protocol:

Similar to POP, and with emails remaining in the server after the client downloads it, e.g. for multiple devices

41
Q

Describe SMTP

A

Simple Mail Transfer Protocol:

Governs how data is sent between mail servers

42
Q

What are the 4 protocol layers?

A

Application layer - layer 4

Transport layer - layer 3

Network layer - layer 2

Data Link & Physical Layer - layer 1

43
Q

Describe the 4th protocol layer

A

Application layer: FTP, HTTP, HTTPS, POP, IMAP, SMTP

Provides user access to applications, websites, files, and emails

44
Q

Describe the 3rd protocol layer

A

Transport layer: TCP

Provides transport of data between devices by splitting files into data packets

45
Q

Describe the 2nd protocol layer

A

Network layer: IP

Provides the routing of packets across the network by addressing

46
Q

Describe the 1st protocol layer

A

Data Link Layer & Physical Layer: Ethernet

Provides the physical transport of data through electrical signals

47
Q

Explain physical protocols

A

These govern how data is sent through physical mediums.

E.g.:

  • Wired or wireless transmission
  • Copper or fibre optic cabling
48
Q

Explain logical protocols

A

These govern the data that is being sent

E.g. bit rate, error checking, ordering of packets, compression and encryption, digital signatures

49
Q

Describe ‘handshaking’

A
  • Two devices communicating over the internet will decide on which protocols to use
  • One device sends a list of protocols, the other sends acknowledgement or rejects them and another is chosen
50
Q

What is the difference between a MAC address and IP address?

A

MAC: fixed to a device when on a LAN

IP: dynamic to a LAN or device on a WAN

51
Q

Describe ‘virus’

A

Small programs which cause physical harm to a computer system

E.g. standard virus, worm virus, trojan virus

52
Q

Describe ‘standard virus’

A

Hides in programs and replicates itself to spread. Aims to delete or damage data

53
Q

Describe ‘worm virus’

A

Replicates itself to use more of the computer’s resources

54
Q

Describe ‘trojan virus’

A

Often causes harm in the background, e.g. creating backdoors, deleting data, changing setups

55
Q

Describe ‘spyware’

A

Watches the user’s activity and sends back information

56
Q

Describe ‘adware’

A

Downloads and displays unwanted adverts and collects marketing information. Tries to direct you to unwanted websites

57
Q

Describe ‘ransomware’

A

Locks your computer, demanding money to get it working again

58
Q

Describe ‘rootkit’

A

Contains tools to allow criminals to access your computer at administrator level

59
Q

Describe ‘pharming’

A

Seeks to change a stored IP address to send you to a fake website

60
Q

Describe ‘phishing’

A

Tries to acquire sensitive information through direct communication by impersonation

61
Q

Describe ‘people’ in relation to network threats

A

A lack of knowledge leads people to be more susceptible to threats when influenced to give away information

62
Q

Describe ‘brute force attacks’

A

Using trial and error to hack an account

63
Q

Describe ‘denial of service’

A

Attempting to bring down websites by using up the web server’s resources: repeatedly tries to access the website

64
Q

Describe ‘data interception and theft’

A

Using specialist hardware and software to secretly monitor network traffic.

Can intercept packets.

65
Q

Describe ‘SQL injection’

A

Attaching SQL commands to a password to alter the SQL statements, allowing access to other accounts or data

66
Q

Describe ‘poor network policies’

A

A set of rules and procedures that network users must follow.

If it is poor or not followed properly then the risk of a breach is increased.

67
Q

Describe ‘penetration testing’

A

A company will invite an expert to simulate a range of network attacks. This attempts to discover weaknesses

68
Q

Describe ‘network forensics’

A

Networks should have software continually monitoring network traffic. This helps with finding the source of attacks

69
Q

Describe ‘network policy’

A

An Acceptable Use Policy, Backup Policy, and Disaster Recovery Policy should exist. These sets of rules govern how the network is used and maintained

70
Q

Describe ‘anti-virus/-malware software’

A

Software dedicated to finding and destroying viruses and malware.

Must be kept up-to-date

71
Q

Describe ‘firewall’

A

This will monitor data packets flowing into a computer.

Packets are received by ports, and the firewall opens ports where data is expected to come to

72
Q

Describe ‘proxy server’

A

A computer which receives internet requests, analyses them against a set of protocols, then sends it out - intermediary

73
Q

Describe ‘encryption’

A

Data is converted from plaintext to cyphertext with an encryption key before being sent on a network

74
Q

Describe ‘user access levels’

A

Users of a system will have different rights depending on their role in the company. This changes what they have access to

A Level Computer Science (20 decks)

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