Networks Flashcards
A network connects a number of digital devices. As well as these devices it requires:
-NIC/ network interface card
- Cabling or WAP/ wireless access point
- A router
- A hub or switch in some networks
- Standards and Protocols
NIC
Network interface card either installed or plugged into the computer. Most computers have them installed
How to connect a wired Vs wireless network
Wired: cabling
Wireless: WAP
Router purpose
Connect network to other networks like the internet
Hub Vs Switch
Hub is “dumb” and sends messages down every wire
A switch has a processor which it uses to direct messages down the correct wire
Standards
Protocols
Standards - shared methods
Protocols - standards for communication
How are internet standards/protocols enforced
No one enforced them but it makes sense to follow them if they want to be connected
LAN
Local area network- all computers on the same site , connections privately owned
WAN
Wide Area Network - a collection of LANS. That communicate with each other eg. The internet
Joins devices remotely using public infrastructure
Bus network type
One cable connects every node / device
All data is transmitted via said cable
- cheap
- slow
-insecure
-cable fail = total fail
Star network
Each device has it’s own cable. Seperately connected to a hub or switch which directs traffic
- fast , large
- greater privacy
- more robust
- expensive to set up
Wireless network
No wired connections , every device uses a wireless adapter.
WAP at the centre , around 20m .
Devices can be portable
Every device needs an adapter
Signals could be inercepted
Mesh network
Many routes through the network
No central hub
Most reliable form of network
Peer to peer
All computers are equal
Cheap, slow , smaller capabilities/capacity
Client server networks
Server stores files for other computers (clients)
More data can be used more work can be done faster
if server has a fault the network fails
Needs technicians
Expensive
Client side processing
Work done by the client
Server side processing
Work done by the server
Fat client pros and cons
- works even if network down
- less strain on server
- more capable computers needed
- need to buy more software
- less control of clients
Thin client pros and cons
- cheaper computers
- buy less software
- control over clients
- relies entirely on server
- created more traffic as constantly communicating w server
Print server
Connected to a shared printer and pass files through to it
Mail server
Sent messages from one client to another
Internet server
Store process and deliver requested info / web pages to users
Name 3 network threats
- hackers
-malware - social engineering
Virus
Creates copies of itself
Not a complete file, a short bit of code
Has an effect when copied into an executable file
When run the virus is executed and does harm
Worm
Similar to a virus but is a complete file
Hidden in storage
Runs on its own and makes copies of itself
Trojan
Looks like a desired file
When opened it infects PC with unwanted code
4 examples of social engineering
- tricks to get past security
- get people to give you their password/ bank details
- scammers and email hoaxes
- phishing and pharming
Spam
Emails sent to you without knowledge or consent often contain marketing
Phishing
Fake email
Pharming
Fake website
Commercial reasons to need security
If a business exposed as having been hacked it looks bad
Personal reasons to n ed security
Protect private data and personal devices from harm
Legal reasons to have security
If a company is handling a clients sensitive data it must be secure
Military and political reasons to have security
Secrets from One country want to be protected from spies from it’s enemy cohtty
Virus checker
Anti malware software on pc
Spam filter
Emails filtered out for suspected spam and put into separate folder
Firewall
Monitors incoming / outgoing network traffic and decides the wether to allow or block traffic based on a defined set of security rules
Eg. Company may block certain sites
Packet filtering
Type of firewall feature
Allows or drops data packets based on simple pre defined rules
Proxy server
Ensures no malware is entering network, and no sensitive data is being shared to outside entities
Internet
A huge mesh network based on shared protocols
Data is transmitted as packets that travel from node to node (packet switching)
Internet adresses
Every internet connection has an IP address - a large number
These numbers are mapped to more useful word based addresses (URLS) using the domain name system (DNS)
Within a local network every individual device also has a MAC address set in the factory
WORLD WIDE WEB
not the same as the internet!!!
Made up of web pages
Defined using protocols:
HTTP = hypertext transfer protocol
HTTPS= same but SECURED
Internet protocols
TCP / transmission control protocol
IP / Internet Protocol
HTTP/ Hypertext transfer protocol
FTP/ file transfer protocol
TCP/IP STACK
layers added in this order
- application layer: added by the software in used
- transport layer: split into packets w TCP
- Internet layer: address added w IP
- Link layer: passed through using MAC addresses
They are taken off in reverse order
Search engines
A web crawler indexes all the pages it can reach
Stores web address plus key words
Use to run search engine
Page ranking
As well as matching key words some sites have priority:
- recently updated
- lots of links to them
- links from high value sites
They will appear higher in the search engine list of links
HTML
Hypertext Markup Language
A declarative language
Paired tags such as <b> and </b> are used to turn format features on and off
