1.3 Computer Networks, Connections And Protocols Flashcards
What is a network
Computers connected together, allowing computer systems to communicate with eachother and share resources with eachother
Features of a LAN
- computers connected together over a small geographical area eg = single buildings or single site
- uses its own hardware and cabling to transmit data eg = Ethernet cables or wifi hotspots
Examples of LANs
- Home network
- School network
- Small company
Features of a WAN
- Computers connected over a large geographical area eg = several sites, country wide or internationally
- uses third party or external hardware and cabling eg = phone lines or satellite connections
- biggest WAN is the internet = interconnecting networks
Advantages of a network
- users can share files
- users can share peripherals eg = printers or scanners
- users can access their files from any computer on the network
- servers can centrally control security, software updates and backup of data
Disadvantages of a network
- increased security risks to data
- malware and viruses spread very easily between computers
- if a server fails, the connected computers may not work
- the computer may run slowly if a lot of data is travelling on the network
How does the number of users/devices affect the performance of networks
- too many users or devices on the same network can cause the network to slow down if theres insufficient bandwidth for the data
- data collisions can occur
How does transmission media affect the performance of networks
- wired connections have a higher bandwidth than wireless connections
- fibre optic cables have a higher bandwidth than copper cables
How does bandwidth affect the performance of networks
- the amount of data that can be sent and received successfully in a given time
- a measure of how much data can be sent on the transmission media
- measured in bits per second, often called bit rate
How does latency (amount of data being transferred) affect the performance of networks
- the delay from transmitting data to receiving it
- latency is caused by bottlenecks in the infrastructure of the network eg - by not using switches to appropriately segment traffic on a network
- hardware like switches and transmission media may not operate at the same speed
Client-server advantages
- security managed centrally
- backups carried out centrally
- central installation of software updates to all computers
Client-server disadvantages
- can be expensive to set up/maintain
- requires IT specialists to maintain
- users will lose access if server fails
Peer-to-peer advantages
- easy to maintain
- specialist staff not required
- no dependency on a single computer
- cheaper to set up
No expensive hardware needed
Peer-to-peer disadvantages
- network is less secure
- users will need to manage their own backups
Features of a WAP - wireless access point
- allows wireless devices to connect to a network without cables
- security is more of a concern with wireless connections
- connection can be less strong or less reliable than a wired connection
Features of a router
- sends data between networks
- lets you connect to the internet
- cant connect to a WAN without a router
- uses an IP address (internet protocol) to route traffic
Features of a switch
- sends data between computers on a LAN
- segment the network by forwarding traffic to the correct location
Features of a NIC - network interface card
- every computer connecting to a network will need one
- allow a device to connect to a wired or wireless network
Features of transmission media (copper cable & fibre optic cable)
Copper cable -
Wired connections assure max bandwidth/securiy/reliability
Fibre optic cable -
Cover longer distances + greater bandwidth
What’s the internet
Worldwide global collection of interconnected networks
What’s hosting
When websites are stored on web servers
Cloud storage advantages
- provide access to files any time, anywhere, any device
- automatic backup
- workers can easily collaberate on documents
- easy to increase storage capcity
Cloud storage disadvantages
- security issues
- need internet connection
- servers provide services
- client request/use services from a server
What’s a topology
Physical arrangement of nodes + connections in a network
Star network advantages
- fewer cables
- easier to add/remove devices
- simple to understand + troubleshoot
Star network disadvantages
- if central switch fails, whole network fails
- can cause bottlenecks in busy networks
Mesh network advantages
- let’s packets be routed round bottlenecks (packets find another route)
- more reliable - single failure wont stop rest of network
Mesh network disadvantages
- more cabling
- complicated to remove/add devices
- complicated to troubleshoot
Connections - Ethernet/wired advantages
- fast transfer speeds
- better physical security
- better range
Connections - Ethernet/wired disadvantages
- cant move easily
- cables = trip hazard
- more cables to add devices
Wifi advantages
- easy to move around
- most devices already have wifi adapter
- easy to add new devices
Wifi disadvantages
- data can be intercepted by anyone
- obstructions can weaken signal strengths
- slower transfer speeds
Bluetooth advantages
- very low power consumption
- ideal for personal device
- easy to make ad-hoc connections
Bluetooth disadvantages
- data can be intercepted by anyone in range
- very short range
- very slow transfer speeds
Ip address features
- identifies networks
- dynamic (changes)
MAC address features
- identifies a device
- static
What’s encryption
A method of scrambling data with a key so that it makes no sense
To read the data the user needs to decrypt the data with the key
What do standards provide
Rules that make sure different manufacturers and providers create products that work together
Examples of standards
- ASCII/UNICODE - character set standards
- IEEE - standards for computer cables
- HTML - standards for creating websites
What are protocols
A set of rules which control the communication between devices on a network
Protocol you need to know + what they do
- TCP/IP = to communicate over LANs and WANs
- HTTP = delivers a webpage
- HTTPS = delivers a webpage (secure)
- FTP = file transfers (upload/download files)
- POP = retrieving an email from a server to our device
- IMAP = accessing emails on multiple devices (sync)
- SMTP = sending an email
What happens as a packet is prepared
The data travels through layers where protocols manage it (adding or removing extra information as required)
What do network layers provide
A division of network functionality so that each layer can operate and be updated independently
Main benefit of using layers
One part of the protocol can be changed/re-written without it affecting the other parts
The steps to packet switching
1) whatever you’re sending is broken down into small packets of data
2) each packets given a header which contains an IP address of the network + device its being sent to
3) it also contains an IP address of the network its sent from
4) the header contains the packet number and the total number of packets
5) when the packet arrives at the destination the informations used to reassemble the data
What happens if a packet is lost
The computer requests the packet to be sent again
What happens if a packet never arrives
It is deleted by the router
