Chapter 6 - Networks Flashcards
Network
Collection of connected computers and their peripherals
LAN
Local area network, confined to one site
WAN
Wide area network, covers a large geographical area
NIC
Network interface cards has a unique MAC number (stored in ROM) for identification and generates electrical signals to allow connection
Hubs
Hardware that connects devices making them a network segment. Signals are transmitted to all connected devices
Switches
Connect network segments, signals only transmitted to intended device
Wireless access points
Allows connection to a LAN without need for cables, usually connected to router
Router
Receives data packets which are forwarded to destination, directs traffic through large networks, connects individual computers to the internet
Protocols
A set of rules that covers data communication
Data packets
Collections of data forming part of a message, sent on a network
Archives
Where old data no longer in use is stored
Failover
When a system detects a potential disaster and sends operations to a duplicate system
HTML
Hypertext markup language, is a text file that allows embedding of many elements and other scripting languages to a web page
XML
Extensible markup language allows separation of HTML display code and data (less HTML needed - smalller file size), allows users to create own tags
CSS
Cascading Style Sheets, adds design to a web page, stored outside of main HTML
Compression
Reducing file size to save storage space or reduce transmission times
Lossy compression
Removing less important data from a file which cannot be recovered
Lossless compression
Does not store repeated details so files can be reconstructed easily
What are advantages of a LAN? (6)
1) Central data storage
2) Easily updated centrally
3) Computer use easily administrated
4) Security policy centrally administrated
5) Users can communicate
6) Peripherals can be shared
What are disadvantages of a LAN? (3)
1) Specialist staff may be needed for maintenance
2) Network problems may affect all users
3) Data accessible from many places
How can security problems caused by wireless access points be dealt with? (3)
1) Encryption
2) Hiding broadcast identities
3) Allowing access to only some MAC addresses
Client-server network
One or more servers provide services to many machines - functions are handled by dedicated machines
Servers
Computers that are set up to handle network functions e.g. database, mail, print servers
Peer-to-peer netwroks
All computers are equal, each computer meets the needs of a user as well as carrying out network functions - easy to set up, can be used online to share files without going through server
What are the disadvantages of peer-to-peer networks? (3)
1) More difficult to maintain
2) Poor security
3) Slow
What is bus topology?
Nodes are attached to a single backbone with terminators. This means it is easy and cheap to set up but a problem can bring the whole network down and there are many data collisons - slow
What is star topology?
Nodes are connected to a central switch or hub so problems do not affect the whole network and there are few data collisions, but can be expensive, more hardware and software is needed
What is ring topology?
Data passes through each node carried in data units called tokens. There are no collisions but problems can bring the whole network down and it is vulnerable to malfunctions
What is a host?
Computer systems that are accessed remotely and hold data
What is DNS?
An internet protocol - domain name system - that translates domain names into IP addresses
What can be included in an acceptable use policy?
Not transmitting offensive material, not using network for marketing, not accessing unauthorised material, not destroying data, not wasting staff time
What is a modem?
Modulator-demodulator. Converts between analogue and digital signals
Network bridge
Hardware that links networks together
Network protocol
Rules and standards for data transfer
TCP/IP
TCP - protocols for connection
IP - protocols for data reconstruction
Domain name
Identifies resource on internet in human friendly way
DSL
Digital subscriber line - uses POTS for internet
