Computer Network Connections/Protocols Flashcards
What is a network
A group or system of interconnected people or things
What is a protocol
An agreement or a set of rules for a computer network
What is a computer
An electronic device for storing and processing data in binary form
What are two types of networks that we use
LAN
WAN
What is a WAN network
Wide Area Network. A network when computers have communication using resources, provided by a third party carrier
How does a WAN need to perform
They would acquire cables, telephone lines, satellites and radio waves
What is the largest WAN in the world
The Internet
What are the advantages of WAN
They cover large geographical areas
Increased privacy
Allows users to share resources and application software
Assists global markets and businesses
IT infrastructure is centralized
Benefits the global market and business
What are the disadvantages of WAN
Spans more congestion
More slower
Poor connectivity
Poor maintenance
Problem with resolving
Instalment fees
Huge demands for security options
What is a LAN
Local Area Network. A network that covers a small geographical location on a small site
What are the advantages of LAN
Spans less congestion
More faster than WAN
Works together from different computers via instant messaging
Can access files from any computer
Works collaboratively on the same file
Can share files
What are the disadvantages of LAN
High setup costs
Local area networking added difficulty to security operation
Control on the customer’s part is lost
Security system should be executed if its essential to protect private data
Weak data protection
High maintenance degree
Maximum damage
What is congestion
Clog or block of something
What are two types of mesh LAN networks
Star Topology
Mesh Topology
What is a network topology
The physical and logical arrangement of nodes and connections in a network
What is a mesh/partial mesh network topology
A network setup where each device is interconnected with one another and can rely data easily
What are the benefits of a mesh network topology
Good resilience, np point in failure
Efficient expansion
Efficient modification
No network disruption
If one computer switches off, the system is unaffected, keeps working like normal
No central switch
What are the drawbacks of a mesh network topology
Difficult administration
Difficult maintenance
High installation costs
If one node is added, more nodes will have to keep getting added
Whats the difference between a regular mesh network and a partial mesh network
Partial Mesh Networks have less nodes
They tend to be in conjunction with star mesh networks for bigger communications
What is a node
A device that can send, receive, read data that is connected to a network
What is a star mesh network topology
A network where all computers, devices and nodes are all connected to a central switch
What are the benefits of a star mesh network topology
If one device is turned off, the network is unaffected, keeps continuing like normal
Fast data transfer to hub as each wire isn’t shared with other computers
What are the drawbacks of a star mesh network topology
If the central switch fails, the whole network is turned off
Additional hardware is required such as a central switch and network cables
What is a wireless mesh network
A communication network made up of radio nodes organized in a mesh topology.
What is a data packet
A unit of data that travels along a network path.
More information about a data packet
Each data packet contains the same number of bytes
Packets may flow through Internet via different routes
Each packet is marked with the packet number so that the packets can be put back together by the receiver
Why does packet switching excel circuit switching
Circuit switching involves a dedicated connection setup between two people (you and the caller)
But packet switching solves the problem of there not being enough lines for billions of people sending data across the Internet
Suppose we want to send a 3MB file to someone via the internet. Explain how we can use packet switching to do this.
- Each file is broken up into equal sized data packets of 512 bytes. Each data packet has 512 bytes. Via packets, we can send them via Internet through different routes
- The request is placed in packets
- Each packet gets an address and number each
- Packets are sent around network
- Packets are sent around host server
- The server does a check to see if all the packets are there
- If not
A timeout is sent - If they have arrived
Packets are placed in order - Request is processed
What is a router
A networking device that forwards data packets between computer networks
What are the benefits of packet switching
- More use than circuit switching
- Data packets are easily able to locate the destination without a channel
- Because packet switching allows packets to be resent, amount of lost data packets is reduced
- Each data packet has a fair same amount of bytes
- Packets are always delivered in the correct order
- Calls are done within a steady bandwidth, dedicated channels and a consistent data rate
What are the drawbacks of packet switching
- Only efficient for voice communication
- Resources are used in the right way
- Dedicated channels for circuit switching are unable for other uses
- The more use, the more expensive
Does packet switching require a dedicated channel?
No
What is a DNS server
Domain Network System
What is the function of a DNS server
Turns the web address into an IP address. It holds parts of a database
How many DNS root servers are there
13
What is a database
A structured set of data held in a computer
What happens if a DNS server doesn’t receive a database request
It passes the request to another server until it has the correct name and IP address. The process will keep repeating until done so
What is an IP address
Internet Protocol Address
A unique address that identifies a device on the internet or a local network
Does our IP address change?
Yes it does. If you are in one part of the country, you are assigned a temporary IP address for that part of the country. If we take our device on holiday however, we are given a different IP address as we are in a different part. If we return back to our original place however, our IP address will change back to our original address before holiday
What is an NIC (network interface card)
A circuit board that functions to enable network communications for devices such as computers and network servers. NIC cards work by transmitting signals at the physical layer and deliver data packets at the network layer
What is a MAC address
Media Access Control address
A unique identifier assigned to a network interface controller for use as a network address within communications in a network segment
What is the link between MAC addresses and NIC cards
A MAC address is assigned to each network interface card by the manufacturer
What is the link between MAC addresses and other connections
There may be more than one MAC addresses if there is an Internet or Ethernet connection
What happens when we request a web page
Each router along the way uses the MAC address of the next router. It also is able to send the data packet on the next part of the journey
What are the differences between an IP address and a MAC address
- MAC addresses NEVER change. IP addresses change when changing location.
- IP addresses are 4 bytes
MAC addresses are 6 bytes - IP addresses are expressed in Denary
MAC addresses are expressed in Hexadecimal
IP addresses are configured by software. MAC addresses are configured by hardware
IP addresses are only used for routing across a WAN/internet
MAC addresses are only used within a LAN
What is a switch
A physical component that governs the signal flow. It is the source of connections
What is a hub
A small device that allows wired devices to connect to a network
What is a WAP
Wireless Access Point
A hardware device or configured node on a LAN (Local Area Network)
What are benefits of WAP
- Low costs than conventional infrastructure
- Easier management and maintenance
- More reliability
- Can be scaled up as needs grow
- Broad transmission range
What are drawbacks of WAP
- Slower than dedicated cable networks
- Limited amount of radio channels, can’t support hundreds of simultaneous connections
- Poor stability
- Limited range of operation
- Less secure due to depending on a secret password
What is the job of a router and a switch
A router routes data packets towards correct destination
A switch connects each node in a network
What are similarities of a router and a switch
- Use of device connection
- Data retrieval from devices
- Correct data determination from destination
- Data transmission
What are some differences of a router and a switch
- Switches use MAC addresses
- Routers use IP addresses
- Switches connect nodes and computers
- Routers connect networks and Internet
- Routers store address of attached devices
- Switches record the address attached
- Switches look for correct addresses
What is an Ethernet connection
A family of wired computer networking technologies commonly used in local area networks, metropolitan area networks and wide area networks.
How does an Ethernet connection work
Delivers stable, speedy, secure, wired connections to the internet and between device
What is transmission media
The way that communication is sent through the network
What equipment is used for an Ethernet connection
Twisted copper cables
Fibre optic cables
Coaxial cables
Original copper cables
What are some types of LAN hardware
Server
Bridge
Hub
Booster
Repeater
Wireless Extender
What is a bridge
A network device that connects multiple subnetworks to create a network
What is a repeater
A networking device that amplifies and generates the incoming signal
What is amplifying
To increase something
What is a wireless extender
A device that extends your main router’s internet signal to another location
What is another word for a wireless extender
Booster
What is a VPN
Virtual Private Network
A non physical, private network that runs on a public network. It combines physical networks into a logical network
What can users access when using a VPN
Virtual Network data
What are some risks of a VPN
- Employees can login the private network from any location.
- They can also access the server from any location.
What are some benefits of a VPN
- Secured connection
- Software separates the Virtual Network from the wider, public network
What are examples of WIFI devices
Laptops
Desktops
Tablets
Smartphones
Smart speakers and lights
What is Bluetooth
A wireless method of device communication over a short distance
It has radio waves of 2.4 GHz
Devices are around 1000cm distanced. They MUST be paired
What are examples of Bluetooth devices
Wireless headphones
Phone connections to car entertainment systems
Keyboards
How do we pair a Bluetooth device
- Create a persistent link between both devices
- A device will ask for a passkey in order for pairing
- Passkeys can only be entered once and will remember paired devices
Why is a passkey useful
Extra layer of security
What are radio waves commonly used for
Communication
What is encryption
The encoding of a data, so it is no longer readable. We then need to use a key to decrypt the data
What is plaintext
The original message to be encrypted
What is ciphertext
The encrypted message
What is a key
A sequence of numbers used to encrypt or decrypt, often data using a mathematical formula
What is decryption
Unlocking the encrypted message via a key, so it is readable
What is encryption algorithm
Formula for encrypting plaintext
What are two inputs
Plaintext
Secret key
What are the two types of encryption
Symmetric Encryption
Asymmetric Encryption
What is symmetric encryption
Uses a single key to encrypt or decrypt a message.
The key must then be given to the recipient of your message for decryption
What is asymmetric encryption
Uses two different keys to encrypt and decrypt a message
A public key is used to encrypt the data
A private key is used to decrypt the data
This is secure as you don’t have to send or reveal your decryption key
What are two wireless encryption standards
WEP (Wired Equivalent Privacy)
WPA (Wi Fi Protection Access)
Why is WEP now useless
Older
Can be cracked in seconds
So no longer be used to protect our home router
What is strong encryption
Useful lifetime of the encrypted data is less than the time taken to break the code
What is weak encryption
Code may be broken in time to use the information, but is no effort to try
What is the current Wi Fi encryption people currently use
WPA2
What is a file server
A server that holds files and databases for backup management
What is a print server
A server that organises printing on different printers
What is an email server
A server that receives emails, detect and block spam and detachable emails to users
What is a web server
A server that hosts an external website
What is a database server
A server holding data
What is the function of the client
To send requests to the server. They then wait for a reply, then receive the reply
What is the function of a server
Waits for client requests. They then receive a request with required processing data, then send the data request back
What is a peer to peer network
A network with no central server
What are benefits of peer to peer networks
- Easy setup
- Built in hardware
- No additional equipment
- Easy file reading on computer
- Good communication
- Suitable for small companies with fewer computers
- There is no central server that controls security and files
- Good direct communication
- Good file sharing
What are drawbacks of a peer to peer network
- Viruses and malware are easily transferred, so there isn’t a central firewall
- Data recovery and backup isn’t done centrally so each computer has its own backup system
- No data retrieval when a computer is switched off
- Files aren’t centrally organised, but are stored on individual computers and can tend to be hard to locate
How does P2P file sharing work
ADVANTAGE
Allows each user to share parts of a file, rather than all downloads coming from a central server. This reduces the bandwidth while file sharing
DISADVANTAGE
But due to illegal distribution of copyright material such as music and films, they are harder to close down.
What is a client server
A network with a client computer and server
What are advantages of a client server
- 1 file only is required for backup
- Files are accessible from any computer
- Email servers provide central places for emails that are assessed from different devices
- Print servers manage all files to be printed. This allows one printer to be shared by many computers
What is a disadvantage of a client server
- Users are reliant on the client server
- High congestion when many clients access the server at the same time
- Limited resources that can affect performance and security of the network
- Need for specialist staff to manage and troubleshoot the network
- Server dependency causes problems if the server fails or gets overloaded with requests
- High setup costs and maintenance costs of the network operating system
What is web hosting
An Internet service offered by companies that will host web pages and files for website
What type of servers does web hosting use
Database servers
What is a hosting service provider
When companies provide multiple general hosting like backup servers
What are benefits of web hosting
- Good bandwidth
- Good equipment monitoring
- Backup web sites remotely
What are drawbacks of web hosting
- Inability to customise the hosting service according to the site’s needs
- Reliance on provider for security, upgrades and maintenance
- Resource connection with other clients on the same server, which affect’s a sites performance and availability
- Resource limits imposed by the provider, such as bandwidth, storage and CPU
- Industry specific challenges such as compliances, regulation and data
What is Cloud
A term used to refer to services that are delivered over the Internet.
It enables users connected to the Internet enabled computer, service access
What are examples of cloud computing applications
Word processing
Database software
Online exams
Business applications
Smartphone apps
What is SaaS
Software as a service
Cloud based servers that allow access to software on demand.
More facts on SaaS
- Requires a subscription basis
- Unlimited access anywhere
- Doesn’t require machine instillation
What are examples of SaaS applications
- Online accounting packages
- CRMs (Customer Relation Management systems)
- Share trading applications
What are some benefits of cloud computing software
- Free, unlimited access
- Data backup is not crucial
- Powerful computers do not require a huge hard drive
What are some drawbacks of cloud computing software
- Personal data is stored on the company computer
- Without an Internet connection, there is unstable service
- Slow internet connections create poor quality of service
- Although cloud services backup data, it isn’t easy for people and organisations to notice the resilience
What are the 3 factors affecting a network’s performance
Bandwidth
Latency
Error rate/collisions
What is latency
The length of time that a packet of information takes to travel through a network
What is bandwidth
The amount of data rate that can be carried through a connection at a time
What is error rate/collisions
The rate of when two computers on a network transmit data signals at the same time
What are examples of communication protocols
HTTP
HTTPS
IMAP
POP
SMTP
TCP/IP
FTP
What is HTTP
Hyper Text Transfer Protocol
A protocol used for accessing and receiving web pages via the Internet
This is written in HTML
(Hyper Text Markup Language)
More information on HTTP protocols
HTTP protocols require and requests for a webpage from the web server. The server then sends its response containing the webpage
What is HTTPS
Hyper Text Transfer Protocol Secure
An extended and better version of HTTP. It is much better as it encrypts information and data so it cannot be accessed by the eavesdropper
What are HTTP and HTTPS protocols commonly used for
Websites
Webpages
Dealing with personal data
What is FTP
File Transfer Protocol
This protocol sends and retrieves files to or from an FTP server
What are graphics
Visual images produced by computer processing.
How does a graphical interface work
Allows files to be dragged from the computer to the server
What are good examples of FTP
Banks
Online shops
Social networking sites
What is an email
Messages distributed from an address, to another address, via a computer
What is SMTP
Simple Mail Transfer Protocol
This protocol only sends mail. That is it. However it doesn’t let you access it.
How is an email sent
- When emails are sent from computers, it is sent to mail servers via the SMTP protocol.
- This is then forwarded to every other SMTP server.
- When reaching the destination of the email server, it it stored
This works for sending email only, not accessing it.
What is POP
Post Office Protocol
This protocol downloads every new message to our local device, due to no longer being available on the mail server.
After each message is downloaded, it is no longer present in the mail server.
What is IMAP
Internet Message Access Protocol
This protocol leaves the message on a server. They can be accessed by many devices, and are only removed if you delete them
After each message is downloaded, it is present in the mail server, unless you modify it.
What is a layer
A group of network protocols that carry out different roles and functions in the communication process.
Layers are a division of network functionality
What is TCP
Transmission Control Protocol
This protocol breaks up messages sent over the Internet into small chunks known as packets. Packets are reassembled at the other end, and detect errors and resend lost messages
How many layers in a protocol stack
4
How do these layers function
Each layer is responsible for covering 25% each of the communication process.
Each four layers are divisions of network functionality, carrying out different roles and functions each
What are the 4 layers
Link Layer
Internet Layer
Transport Layer
Application Layer
How do we know the correct layer to use
The application applied to sending data will determine the correct protocol for communication
What is the function of the Application Layer
When web applications create data to send in this layer.
SMTP, FTP, HTTP and HTTPS specialise in the area
What is the function of the Internet Layer
This layer is responsible for packet routing. Routers operate on this layer. A source and destination address are written on the packets, ready for transmission
What is the function of the Transport Layer
This layer creates communication between 2 computers (hosts).
Data is divided up into packets and assigned a packet number. Packets are reassembled by the recipient’s Transport layer.
This layer specialises in TCP
What is the function of the Link Layer
This layer removes the MAC address and passes packets up to the Internet Layer
What are benefits of layers
- Breaks communication into manageable chunks
- Allows developers to focus on one area of the network without worrying about others
- There are set rules for each layer
- Self contained
- Functionality of one separate layer can be changed without affecting the functionality of the other layers
- Different hardware or software operates on a particular layer, so it provides compatibility between providers and systems
- Shows how the manufacturer’s routers operating on the Internet Layer, operates with another manufacturer’s NIC (Network Interface Card) operating on the Link Layer
- Senders and receivers using different software and hardware can communicate with the same layer protocols
What is failover
When redundant components, hardware or capacity is built into the network.
