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Computer Science - Paper 1 > Networks > Flashcards

Networks Flashcards

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1
Q

LAN

A
  • local area network
  • two or more connected devices with close geographic locations
  • share peripherals
  • share files, folders and data
  • can be wired (Ethernet cables) or wireless (WiFi)
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2
Q

WAN

A
  • wide area network
  • two or more connected LANs
  • share files, folders and data
  • organisations hire infrastructure from telecommunication companies who own and manage the WAN
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3
Q

Bandwidth

A
  • amount of data that can be sent over a network in a given time
    can be effected by:
  • the amount of users on a network = too many can cause congestion
  • wired connections are usually faster because they have a physical connection
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4
Q

NIC

A
  • internal hardware that allows a device to connect to a network
  • exist for wired and wireless connections, typically built into the motherboard (can be bought as separate cards)
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5
Q

Switches

A
  • connect devices to a LAN

- receive data in frames from one device and transmit it to a device on the network with the correct MAC address

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6
Q

Routers

A
  • transmit data between networks
  • direct data packets to the correct destination
  • used in homes or offices to connect a LAN to the internet
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7
Q

Ethernet Cables

A
  • used to connect devices in a LAN
  • CAT 5e or CAT6 cables
  • they are made of twisted pairs of cables, containing four pairs of copper wires (the twisting reduces risk of interference)
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8
Q

Coaxial Cables

A
  • made of a single copper wire that’s surrounded by a plastic layer for insulation and a metallic mesh = provides shielding from outside interference
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9
Q

Fibre Optic Cables

A
  • transmit data as light

- high performance cables = don’t suffer interference and can transmit over large areas without loss of signal quality

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10
Q

WiFi

A
  • two frequency bands = 2.4GHz or 5GHz
  • WiFi bands are split into overlapping channels that cover a small range
  • affected by interference of overlapping channels
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11
Q

Client-Server Network

A
  • all clients are connected to a server/ powerful computer
  • central updates and backups
  • if the server shuts down then nodes are unable to access their data
  • require expensive technician to maintain the network
  • usually require authentication for users
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12
Q

Peer-Peer Network

A
  • all nodes are connected to each other with no central sever
  • no central updates or backups
  • network functions normally when one device is out of use
  • files and folders are stored on the individual device
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13
Q

Star Network

A
  • all devices are connected to a central switch/server that controls the network
  • network wont fail if one device is turned off, easy to add more devices, better performance that other setups
  • wires are expensive, whole network is affected if there is an issue with the switch
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14
Q

Bus Network

A
  • all devices are arranged in a line and connected to a single backbone cable
  • devices send data up and down the cable = data collisions and a slower network
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15
Q

Ring Network

A
  • data moves in one direction around the ring to avoid collisions
  • only one device can send data at a time
  • data must be sent to all devices between sender and receiver = time consuming
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16
Q

Mesh Topolgy

A
  • all nodes are connected to each other(mesh) directly (full mesh)
  • data takes the fastest possible route
  • no single point at which a network can fail
  • resources to create a mesh network become expensive = lots are required
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17
Q

Network Protocol

A
  • set of rules/ instructions on how devices communicate and data is transferred over a network
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18
Q

MAC Address

A
  • assigned to all network-enabled devices by the manufacturer
  • unique to every device and cannot be changed
  • 48 or 64 bit binary numbers
  • used by Ethernet protocol on LANs
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19
Q

IP Address

A
  • used when sending data over TCP/IP networks
  • they are assigned manually (static) or automatically (dynamic) before the device can access the network

dynamic = assigned to device by the network server so the device may have a different IP address every time they join

static = used for hosting website son internet etc as they’re permanent = more expensive to maintain a single IP address

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20
Q

Packet switching

A

1) sending device will split data into packets and give each of them a number = order
2) reads header and decides which way to send the packet next
3) the way its sent is dependent on network traffic - quickest route is chosen by routing algorithm
4) packets take different routes and are the re-ordered
5) receiving device checks periodically if packets have been received to make sure none go missing in transit = if not a timeout message is sent to the sender
6) If all data is received and the checksums match a receipt conformation is sent to the sender

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21
Q

HTTP

A
  • hyper text transfer protocol

- used by web browsers to access websites and communicate with web servers

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22
Q

HTTPS

A
  • hyper text transfer protocol secure

- HTTP but with encryption for all information that’s sent

23
Q

FTP

A
  • file transfer protocol

- used to access, edit and move files between devices on a network (access server files from client computer etc.)

24
Q

POP3

A
  • post office protocol 3

- used to retrieve emails from server = server holds the email until you download it and then its deleted by the server

25
Q

IMAP

A
  • internet message access protocol
  • used to retrieve emails from server = server holds the email until you delete it, your copy is only a download
  • very common for web based email clients
26
Q

SMTP

A
  • simple mail transfer protocol
  • used to send emails
  • used to transfer emails between servers
27
Q

Network protocol layers

A

LAYER 4 - application layer = turns data into websites and apps etc (HTTP,FTP,SMTP)
LAYER 3 - transport layer = controls the flow of data, like splitting data into packets etc (TCP)
LAYER 2 - network layer = makes connections between networks, handles traffic and directs data packets (IP)
LAYER 1 - data link layer = passing data over the physical network, responsible for how bits are sent as signals over cables (Ethernet)

28
Q

Advantages of using layers

A
  • breaks network communication between manageable pieces
  • layers are self contained = can be edited without affecting the other layers
  • companies have to make compatible, universal hardware and software = every companies layers are relatively similar
29
Q

The Cloud

A
  • uses the internet to store files and applications = a form of hosting
  • an extension of a traditional client server network = files are stored centrally on a network server
30
Q

Advantage of the Cloud

A
  • users can access files from any connected device
  • easy to increase how much storage is available
  • no need to buy expensive hardware to store data
  • no need to pay IT staff to manage hardware
  • provides security and backups for you
  • software will be updated automatically
31
Q

Cons of the Cloud

A
  • need internet connection to access files
  • dependent on host for security and backups
  • data can be vulnerable to hackers
  • unclear who has ownership of data in the cloud
  • subscription fee for the cloud and software may be expensive
32
Q

Virtual Networks

A
  • software based networks
  • created by partitioning off some of a networks physical bandwidth to form a separate network
  • several virtual networks can exist on the same physical network = networks are more efficient
  • each has its own security and firewall and can only be accessed by certain software or login info
33
Q

Virtual Private Network

A
  • type of virtual network that can be used to send data over a large network; like WAN or the internet
34
Q

Virtual LAN

A
  • allows you to split a LAN into smaller networks using the same hardware
35
Q

Passive Attack

A
  • the hacker monitors data travelling on a network and intercept any sensitive information that they find
  • best defence is data encryption as they’re very difficult to detect
36
Q

Active Attack

A
  • when someone attacks a network with malware or other planned attacks
  • best defence is a firewall = more easily detected
37
Q

Insider Attack

A
  • when someone within an organisation takes advantage of/exploits their position and steal information
38
Q

Brute Force Attack

A
  • hacker creates software that attempts to hack into a network by trying every possible combination of login details
  • strong passwords or locking accounts after a certain amount of attempts can reduce this
39
Q

Denial of Service Attack

A
  • hacker floods a network with traffic so that users are unable to access a part of a network or website = makes network very slow
40
Q

Malware

A

= malicious software

41
Q

Malware typically;

A
  • deletes or modifies files
  • scareware = tricks user into thinking the device has a virus so they pay for issues to be fixed
  • locking files = ransomware encrypts all files on a device
  • spyware = secretly monitors the users actions and send info to hacker (when they press a key)
  • rootkits = giving malware and hackers administrator-level access to devices
  • opening backdoors = find holes in someone’s security that can be used for future attacks
42
Q

Malware can access your device by;

A
  • viruses attach themselves to files and when the user open or copy files the virus spreads
  • worms self replicate without the users help and spread quickly exploiting faults in network security
  • trojans are malware disguised as legitimate software they dont replicate as the user installs them unknowingly
43
Q

Social Engineering

A
  • an individual attempts to trick someone who has the rights to access sensitive data into sharing this information with them by posing as someone they believe to have authority
44
Q

Phishing

A
  • a hacker will send an individual an email pretending to be from a well known company claiming there is an issue with their account and asking them to re-enter their details on a page that looks like the website = they can then access their sensitive information
45
Q

SQL Injection

A
  • standard query language

- SQL injections are pieces of SQL typed into a websites input box which then reveal sensitive information

46
Q

Good Network policy

A

= rules of how users should interact/ communicate with each other on the network
- regular tests for weaknesses
- use complicated passwords and change them regularly
- enforce user access levels
- instore anti malware and firewalls to destroy malware
- encrypt sensitive data
= prevents people from gaining access to sensitive information

47
Q

Penetration testing

A
  • when organisations employ someone to try and hack into their network to be made aware of any weaknesses
  • the results are reported to them
  • members of the network/ company are unaware
48
Q

Network Forensics

A
  • investigations that aim to find out why attacks have been carried out against a network
  • an organisation needs a system that captures data packets as they’re sent over the network, the packets are analysed after the attack to find the cause
49
Q

Passwords

A
  • help prevent unauthorised access

- passwords should be strong, include characters, capital letters, symbols and numbers (can also have a character limit)

50
Q

User Access Levels

A
  • control which aspects of the network different people are able to access based on their status in the network/company
  • prevents sensitive data being exploited
51
Q

Anti-Malware Software

A
  • designed to stop malware damaging an organisations network and the devices on it; including anti-virus software
  • firewalls = block unauthorised access, examine all data going in and out of a network
52
Q

Encryption

A
  • data is translated into code as it’s sent over a network which only with a someone with the correct encryption key can decode
  • encrypted text = cipher text else = plain text
  • secure
53
Q

Validation

A

= checking that an input meets certain criteria

54
Q

Ransomware

A
  • a type of malware that uses encryption to lock a user out of their files

Computer Science - Paper 1 (3 decks)

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