Networks Flashcards
What is a network?
Interconnection of computers and other pieces of hardware to facilitate communication and the sharing of resources
What are the pros of having a network?
- Resources such as printers, internet connections and files can be shared (saving money and effort)
- Communication (over email, instant messenger)
- Backing up data to a different computer is straightforward
What are the cons of having a network?
- Managing networks are expensive, and require specialist skill
- Security procedures are necessary to prevent unauthorised access
What are the types of network?
PAN - devices owned by a single user connected via Bluetooth
LAN - network covering small geographical area, e.g. single building, hardware owned by a single cooperation or person
WAN - covers a large geographical area, with shared ownership of some hardware (e.g. internet)
What are the positives of wired networks?
- more secure (physical connection is needed within the ‘building’ for hackers
- less prone to interference
- high bandwidths, so lots of ppl can be connected at same time
What are the positives and negatives of wireless networks?
- much easier to add a device
- portable
- not very secure
- prone to interference
- low bandwidths
How do wired networks connect?
Optical fibre cabling - very fast connections, able to handle lots of computers sharing same connection
copper cabling - cheaper, slower, quick enough for most activities single computer would perform online
How do wireless networks connect?
Radio waves (connection medium)
What is a network topology?
Pattern in which hardware on a network is positioned, including connections
What is Star network topology?
Where every device is connected to a switch, at the centre of a network.
- Very few data collisions (each device has dedicated line)
- Strong centralised security
- one workstations failing has no effect on functionality
- lots of expensive cabling
- adding devices needs expert
What is Bus network topology?
Backbone (Central cable) running between 2 terminators, connecting all the devices
- uses relatively less cabling (inexpensive)
- additional devices can be added easily
- collisions can occur, multiple transmissions on shared backbone
- large number of devices, means slower transmissions
- low security, ‘eavesdropping’
What is a network protocol?
a set of rules that govern how a computer communicates on a network.
What is ethernet?
-Family of protocols
- Set of rules that govern how data is formatted for transmission across LAN
What is Wi-Fi?
-Brand name
- rules control how data is transmitted on a WLAN
what is TCP/IP?
- two protocols work together
- Transmission control protocol and internet protocol
-collective role is to break data into packets, that knows where to be delivered and where it was sent from
what is UDP?
- user datagram protocol
- transmits data packets very quickly
- doesn’t check to see whether each packet arrived, unreliable
What is HTTP?
Hypertext transfer protocol
- governs how hypertext (language of world wide web) is moved around the Internet, from device to device
What is HTTPS?
HTTP secure
- encrypts data sent across the internet
- favoured when sending passwords, credit card num etc.
What is FTP?
File transfer protocol
- how files are moved from one computer to another across internet
- relied upon in building websites, and moving files from developer computer to server, where it can be accessed quickly
what is SMTP?
Simple mail transfer protocol
- POP3 To retrieve emials
- sends emails from one server to another
what is IMAP?
email protocol allows multiple devices to access same email address
What is IP address?
Internet Protocol Address, a unique number, to identify every device connected to Internet.
Name 4 methods of keeping network secure.
- authentication
- firewall
- MAC address filtering
- encryption
What is encryption?
the scrambling of data using a key, so only the recipient can decrypt and read the data.
What are firewalls?
Hardware, software of both.
firewalls can be told to block certain traffic (e.g. emails from certain IP address) and only allow certain traffic.
What is MAC address filtering?
each computer has MAC address, cannot be changed. Unique identifier, specific devices can be blocked from a network.
What are the 4 layers in TCP/IP Model?
Application Payer
Transport Layer
Internet Layer
Link Layer
What protocols works at each layer?
Application - HTTP, HTTPS, FTP, IMAP, SMTP
Transport - TCP, UDP
Internet - IP
Link - Ethernet, WiFi
Describe each layer.
Application - where network apps, e.g. browers operate
Transport - establishes communication between sender and recipient
Internet - packaging data for transmission (packets)
Link - physical components operate at this level.
