Networks (PAPER 1) Flashcards
What does LAN stand for
Local Area Network
How large of an area does a LAN cover
a small geographical area located on a single site
Who typically owns the hardware for a LAN
the organisation that uses it
What are the benefits of using a LAN
- easier to share files
- hardware can be shared
- software can be installed / updated on all computers at once
- communications are cheaper and easier
- user accounts can be stored centrally
What is a WAN
a network that connects LANs
What does WAN stand for
Wide Area Network
Who owns WANs
large telecommunication companies that are loaned out to organisations
How can WANs be connected
fibre or copper telephone lines, satellite links or radio links
What 4 factors affect performance of networks
- bandwidth
- wired / wireless
- choice of hardware
- network topology
What is bandwidth
the amount of data that can be transferred in a given time
which is faster : wired or wireless
wired
What type of cables are the best for a fast network
fibre optic cables are better than copper
What factors does wireless performance depend on
- range of device
- amount of interference from other wireless networks
- physical obstructions
What 3 pieces of hardware are required for a network
- Network Interface Controller
- Switches
- Routers
What does NIC stand for
Network Interface Controller
What is a NIC
an internal piece of hardware that allows a device to connect to a network
What do switches do
- how do they do this
connect devices on a LAN
- receive data (frames) from one device and transmit it to the device on the network with the correct MAC address
What are routers responsible for
transmitting data between networks
What do most home ‘routers’ consist of
router, switch, WAP
What unit is data sent in
packets
What are the two most common Ethernet cables and what type of cable are they
- CAT 5e and CAT 6
- twisted pair cables
what are coaxial cables
cables made of a single copper wire surrounded by a plastic layer for insulation and a metallic mesh which provides shielding from outside interference
how do fibre optic cables work and what are their benefits
transmit data as light
- high performance , travel over large distances without loss in quality, don’t get interference
How do wireless networks transmit data
through radio waves
Why are wireless networks better than wired networks
- cheaper - less cabling
- move around while still being connected
What are the two most common wireless technologies
WiFi and Bluetooth
What are the properties of Bluetooth
- usually direct connection between two devices
- range of typically around 10 metres
- low bandwidth compared to WiFi
- Often used in mobile / wearable devices
What are the properties of WiFi
- can be used to connect multiple devices
- connection range of around 40 - 100 metres
- high bandwidth compared to Bluetooth
- often used for routers, desktops, laptops etc.
What does WAP stand for
Wireless Access Point
What is a WAP
a switch that allows devices to connect wirelessly
What do devices need to connect
a wireless NIC, a USB dongle can also be used
What are the two main types of network model
Client Server and Peer-to-Peer Networks
What is the make-up of a client-server network
managed by a server, the devices connected are clients
Where are files and software stored in a client-server network
centrally on the server
What is the client-server relationship
- client sends request to the server
- server processes the request and responds
What sorts of things are stored on the server
- user profiles
- passwords
- access information
What are the pros of a client - server network (5)
- easy to keep track of files
- easy to perform back-ups
- easier to install and update software
- easier to manage network security
- reliable and servers are always on
What are the cons of a client - server network (4)
- expensive to set up
- IT specialists to maintain network and server
- server dependence
- server can become overloaded
What are the principles of a P2P network
all devices are equal, connecting directly to each other
- files are stored on individual devices
What are the pros of a P2P network
- easy to maintain
- no dependence on server
What are the cons of a P2P network (5)
- no centralised management
- Backups are more complicated
- duplicate files - easy to lose track
- less reliable, data is lost if once fails
- machines are prone to slow down when other devices access them
What are the two most important network topologies
- star topology
- mesh topology
What happens in a star topology
all devices are connected to a central switch or server that controls the network
What does a central switch do in a star topology
allows many devices to access the server simultaneously
What are the pros of a star topology
- rest of network is unaffected if a device / cable disconnects
- easy to add more devices to the network
- better performance - data goes straight to central server
What are the cons of a star topology
expensive - lots of cabling for wired network
- whole network is affected if server goes down
How does the bus topology work
- what are its pros and cons
- all devices are arranged in a line connected to a single backbone cable
- devices send data in both directions, causing data collisions
How does the ring topology work
- what are the pros and cons
- data moves in one direction around the ring
- one device can send data at a time
- data passes through many devices before reaching its destination
What are the principals of a mesh topology network
- decentralised - all devices are directly / indirectly connected to each other
- data is sent along the fastest route from one device to another
What are the pros of a mesh topology
- ## no single point of failure
What are the cons of a mesh topology
- how can it be prevented
expensive - lots of wiring
- through using a wireless network
What are the two types of mesh topology
- what is the difference
- full mesh topology - all devices are connected to each other
- partial mesh topology - not all devices are fully connected
What is a network standard
a set of agreed requirements for hardware and software
why are network standards important
they allow manufacturers to create products and programs that will be compatible with products and programs from other manufacturers
What is a network protocol
a set of rules for how devices communicate and how data is transmitted across a network
What do communication protocols specify (3)
how communication between two devices must start and end, how the data must be organised and what the devices must do if data goes missing
What is a MAC address
a unique identifier assigned to all network enabled devices by the manufacturer
What do MAC addresses look like
48 or 64 bit binary numbers, often seen converted into hexadecimal for ease
What do LAN switches do to MAC addresses
- what protocol are they mainly used by
MAC addresses are read and used to direct data to the right device
- Ethernet protocol
When are IP addresses used
when sending data between TCP / IP networks
What does IP stand for
Internet Protocol
What are the two versions of IP addresses, what are their lengths
- why was the second one created
IPv4 (32 bits), IPv6 (128 bits)
- because of the increasing number of devices that need unique IP addresses
How many possible IP addresses are there for each of two types of IP address have
- How are they commonly notated
IPv6
- 2^128
- 16 bit chunks, each given as a hexadecimal number with colons to separate
IPv4 - 2^32
- 8 bit chunks, each given as a denary number with decimal points to separate
What is TCP / IP
the most important protocol
it dictates how data is sent between networks
What two protocols does TCP /IP consist of
- What do they stand for and what are their roles
TCP - Transmission Control Protocol
- sets rules for how devices connect on the network.
- It splits the data into packets and reassembles them once they reach the receiving device
- checks data is correctly sent and delivered
IP - Internet Protocol
- responsible for directing packets to their destination across the network
HTTP
- What does it stand for
- what is it used for
- Hyper Text Transfer Protocol
- Used by web browsers to access websites and communicate with web servers
HTTPS
- What does it stand for
- what is it used for
- Hyper Text Transfer Protocol Secure
- a more secure version of HTTP (used by web browsers to access websites and communicate with web servers)
- encrypts all information sent and received
FTP
- What does it stand for
- what is it used for
- File Transfer Protocol
- Used to access, edit and move files between devices on a network
POP3
- What does it stand for
- what is it used for
- Post Office Protocol version 3
- Used to retrieve emails from a server
- Server holds the email until you download it, then it is deleted
IMAP
- What does it stand for
- what is it used for
- Internet Message Access Protocol 3
- Used to retrieve emails from a server
- Server holds the email until you delete it, only a copy is downloaded
SMTP
- What does it stand for
- what is it used for
- Simple Mail Transfer Protocol
- used to send emails. Also used to transfer emails between servers
What is a layer
a group of protocols that have similar functions
What are the general properties of a layer
- self - contained
- serves the layer above
What are the four layers of network protocols
- What are examples of each
- What are the roles of each
4 - Application
- Turning data into websites and other applications and vice versa
- HTTP, FTP, SMTP
3 - Transport
- Controlling data flow
- TCP
2 - Internet
- Making connections between network and directing data
- IP
1 - Data Link
- Passing data over the physical network (as electrical signals)
To what layers can data be passed
to any adjacent layer
What are the advantages of using network layers
- breaks network communication into manageable pieces
- specialists can be used
- self contained - changing one won’t affect others
- Having standards make them compatible and universal
What is the internet
a WAN that connects devices and networks from all over the world
What does WWW stand for
world wide web
What protocol is the internet based around
TCP / IP
What does MAN stand for
Metropolitan area network
What does PAN stand for
Personal Area Network
What are URLs
addresses used to access web servers and resources on them
What does DNS stand for
Domain Name Service
What is a DNS used for
to translate website domain names into IP addresses
What are domain name servers
servers which store IP addresses and matching domain names
What is server hosting
When a business uses its servers to store files of another organisation
What is a common use for server hosting
hosting websites on web servers
What services can be offered to people through server hosting
clients can access data storage, software and processing power remotely over the internet
What is cloud computing
when people can access data storage, software etc. remotely over the internet
What is a freemium model
when customers are able to try some parts of the service for free then have the option to pay to upgrade to the full premium service
What are the pros of the cloud (5)
- users can access files and applications from any connected device
- easy to increase how much storage is available
- no need to buy expensive hardware
- cloud host provides security and back-ups
- software updated automatically
cons of the cloud
- needs a connection to the internet
- dependency on host
- vulnerable to hackers
- unclear who has ownership over data
- subscription fees may be expensive
What are the five types of network attack
- passive attack
- active attack
- insider attack
- brute force attack
- brute force attack
- denial of service attack (DoS)
What is a passive attack
someone monitors data travelling and intercepts sensitive information
What is lawful interception
when governments use data interception for cyber security
What is an active attack
attacking a network using malware or planned attacks
How are active attacks defended
through the use of a firewall
what is an insider attack
when someone in an organisation exploits their access to steal information
how to defend against a passive attack
data encryption
what is a brute force attack
trial and error - software produces likely codes and tries them all
how to defend against a brute force attack
using strong passwords
What is a denial of service attack
a hacker floods a network with useless traffic, making it slow / inaccessible
what is malware
malicious software that is installed on someone’s device without their knowledge or consent
What are the six most common actions of malware
- deleting or modifying files
- scareware
- locking files (ransomware)
- spyware
- rootkits
- opening backdoors
What is scareware
telling the user their computer is infected to scare them into following malicious links or paying for problems to be fixed
What is spyware
something that monitors user actions and sends information to the hacker
What do rootkits do
alter permissions and give hackers administrator level access
What is a backdoor
a hole in someone’s security which can be used for future attacks
What are the three most common types of malware
- how do they work
VIRUS
- copy themselves to files, spread by users copying infected files, activated by opening the infected file
WORM
- self replicate, attach themselves to files
TROJAN
- malware disguised as legitimate software to trick user into downloading it
What is social engineering
a way of gaining sensitive information or illegal access to networks by influencing people
what is phishing
- criminals send emails to people claiming to be from a big company
- the email often contains spoof versions of the company’s website
- they request the user to update personal information
- the hacker can see the data that is entered
What are common giveaways that an email is a scam
- spelling error
- not personalised
- incorrect information
What does SQL stand for
Structured Query Language
What is an SQL injection
- SQL is typed into a website’s input box
- if input validation isn’t strong enough, people can access other people’s information
What are things organisations should do to protect them from vulnerabilities
- brief description of each
penetration testing
- simulations of potential attacks to identify potential weaknesses
Physical security
- locks, surveillance equipment etc. for both intentional and unintentional damage
Passwords
- helps prevent unauthorized access
User Access Levels
- restrict access to limit insider attacks
Anti-malware software and Firewalls
- prevent malware attacks
Encryption
- no third-party can decipher text
