Networks(1.3) Flashcards
What is a P2P network
- In P2P networks, all devices are EQUAL, connected to every other device (no central location)
- Files are stored individually on machines and then share with others
- P2P is common when sharing files online, especially when video streaming e.g. Skype
What are the benefits of a P2P network
- Cheaper to set up than Client Server network
2. Easier to set up and maintain and no expertise required
What are the drawbacks of a P2P network
- No centralised location
(requires manual back-ups and updating of software) - Copying files creates duplicates of files, so harder to keep track of latest versions
- Less reliable and data may be lost if one machine fails
What is a client server network
- A Client-Server network is managed by one main server, and it is connected to all its devices (clients)
- Files and software are stored on the server, instead of individual client machines
- Clients send requests for data to the server, and the server processes this and responds (client-server relationship)
- Much more common than P2P networks
What are the benefits of a client server network
- Easily perform back up of all stored data
- Easier to install and manage software
- Easier to manage network security
- Central location for all files and data
What are the drawbacks of a client server network
- Expensive to set up and maintain (required expertise and specialists)
- If server fails, then ALL connected devices will stop working
What is a LAN
A LAN covers a small geographical location on a single site e.g. school, office, shop, home and can be connected either by wired (using Ethernet) or wireless (using WIFI) connections
What is a WAN
- A WAN connects multiple LANs spread across multiple geographical locations
- WANs are connected by using copper or fibre optic cabling
What is a wireless access point (WAP)
- A device that creates a wireless LAN which other devices can connect to
What is a router
- A device which transmits the data between multiple networks (at least 2 networks)
- allows connection from a LAN to the internet
What is a switch
- A device which connects other devices on a LAN
- they receive data from one device and transmit to another device, with the correct MAC address
What is a Network interface card (NIC)
- An internal component that allows a device to connect to a network
What is an ethernet wire
- Made up of 4 pairs of twisted copper wires
- mainly used to physically connect devices on a LAN
What is coaxial cabling
- Made up of single copper wire surrounded by a plastic layer (insulation) and metal mesh (shielding)
- Mainly used by phone companies and internet providers
What is fibre optic cabling
- Made up of a glass core which refracts light as data travels, over long distances
- used for high speed internet and cable TV services
How can bandwidth affect performance
- higher bandwidth means better network performances as more data can be transferred at a given time
- More users sharing bandwidth can slow down performances
How can connection type affect network performance
- Wired connections are more reliable/faster than wireless, but are not as portable and require more cabling to connect more devices
How can number of devices affect network performance
- The more devices connected, the slower the network may perform
What is the cloud
- A cloud host stores the data of another organisation, using its own servers, storage and software, accessible only via the internet
What are the benefits of the cloud
- access data from any connected device
- easy to increase storage
- no need to pay for IT staff
- provides auto updates and back-ups
What are the drawbacks of the cloud
- must need internet access
- dependency on the cloud host for security and back-ups
- often subscription based so can be more expensive
What is the World Wide Web (WWW)
- a collection of websites hosted on web servers, which we can access using the HTTP protocol
How does the domain name server work (DNS)
- Each website contains a URL (uniform resource locator) which we can access using the DNS
- Translates a websites domain name into its IP address, so we don’t need to remember IP addresses
What are the positives of wired networks
- Much ore reliable
- faster and stable connection (not affected by interference)
- less likely to be affected by hacking
What are the drawbacks of wired Networks
- wires can affect portability/movement
- costs more to add additional devices
What are the positives of wireless networks
- easier to connect more devices
- can move around
- costs less vs wired
What are the drawbacks of wireless networks
- more devices means affected by interference
- it is not as fast or stable as a wired (Ethernet) connection
- is more prone to be affected by hacking
What is a star network topology
- all the devices are connected to a central switch or server that controls the network
What are the advantages of Star Network topologies
- If one device or cable fails, the rest of the network will not be affected.
- Easier and simpler to add more devices (just connect to central).
- Limited or no data collisions as devices have independent connections
What are the negatives of Star Network topologies
- If wired, then each device requires separate cable/wire so can be expensive with many devices.
- If the main server/switch fails then the entire network will fail (unable to access any data).
- Additional cabling required for every device
What is a mesh network topology
- In a Mesh topology, there is no central location as each device is directly or indirectly connected to another device. Data is sent across the fastest route from one device to another
What are the advantages of Mesh Network topologies
- No single point where network can fail (unlike star) just use another route to send data
- Easily detect a fault in the network
What are the negatives of Mesh Network topologies
- Not as scalable as star topology, because adding one device means having multiple connections to the other
- Each device will need many I/O ports which is not always possible
What are network layers
- small sections (divisions) of network functionality
- Layers are SELF CONTAINED, so developers can work on one aspect of the network without affecting the remaining layers.
What are the layers in order
- Application layer
- Transport Layer
- Network/Internet Layer
- Link/Network access layer
What are network protocols
- sets of rules used by devices for communication across a network
What is the TCP/IP protocol
- (transmission control protocol/internet protocol)
split data into packets and then reassemble into correct order (check for errors). IP is responsible for packet switching
What is the HTTP/HTTPS
(hyper-text transfer protocol (secure)) used by web browsers to access websites
What is the FTP Protocol
- (file transfer protocol) move files between a network
What is the POP Protocol
- (post office protocol) ʹ retrieve emails from a server. Email is held until downloaded, then it is deleted
What is the IMAP Protocol
- (internet message access protocol) similar to POP but only deleted when you choose to do so
What is the SMTP Protocol
- (simple mail transfer protocol) send emails between servers
What is packet switching
- used by routers to direct data packets across networks
How does packet switching work
1 - data is split into packets (given headers which contain source and destination IP address) and a number to show order
2 - Routers direct the packets through the best/fastest route depending on amount of traffic. Each packet can take a different route.
3 - As they arrive, the packets are rearranged into correct order.
4 - If any packets were lost during sending, sends signal back to resend the packet and then sends receipt confirmation when all the packets have arrived.
