Chapter 6 - Comouter Communication Flashcards
What is a node?
A device on a network
What is LAN?
Local area network
Confined to one site
Connected and maintained by an organisation
What is a WAN?
Wide area network which covers a large geographical area
They often connect LANs together
They allow a business to function from any location
What are cables used for?
To connect different devices in LANs
Two different types of wires?
Copper cable/UTP: light and flexible, easy to install
Fibre optic cable: for longer distances, transmits signals using waves, cheaper
What is a hub?
Hardware devices which connect many network devices together making them into a network segment.
What are switches?
They connect network segments or devices
They also act as bridges, which connect more than one network - allowing them to function as one network
Difference between Hun and switches?
A switch only transmits a message to the device intended instead of all connections.
Hubs have a number of input and output ports which are all connected, a signal arriving from one is transmitted to all others
What is an NIC?
Network interface card Generates and receives suitable electrical signals Carries out simple addressing Built into the motherboard Acts as a LAN adapter
What is a MAC address?
Every NIC has a unique number stored in ROM, this is called its MAC address
MAC addresses allow each node on a network to be identified
What is a wireless access point?
They allow connection to a LAN without the need for physical cables using standards such as WiFi.
What are access points often connected to?
A router
Pros of access points
Save money and effort because new bodes can be added without the need for more cables
How are Security risks of access points dealt with?
Encryption
Hiding their broadcast identities
Allowing access to only certain MAC addresses
What is a router?
Receives day in the form of packets and forwards them to their destination which is often another router
Used to direct traffic in the internet but also to connect small individual computers to the Internet service provider
Advantages of LANs?
Central data storage makes data sharing possible and convenient and makes backups easier
Computers in LAN are easily upgraded or reconfigured centrally
Security policies are centrally administered
What is a client server network?
One server(computer set up to handle network functions) produces services to many client machines where the users work.
What is a peer to peer network?
All computers are equal
Each computer serves the needs of the user as well as carrying out networking functions
What is a topology?
Layout of network components
What is a bus topology?
Computers and other devices are attached to a back bone. A terminator is attached at each end to prevent reflection of signals, signals travel in either direction.
Pros of bus
Easy to set up
Cheap
Cons of bus
Problem with backbone can bring the whole network down
Many data collisions slow the network down
What is a star topology?
Client machines are connected to a central switch which is usually in turn connected to one or more servers. Signals travel in either directions
Pros of star?
Robust - problem with a connection do not affect the whole network
Fewer data collisions so faster than bus
Cons of star?
Needs more expertise to maintain
Can be expensive to set up because more building work involved
What is a ring topology?
Data passes through each node, carried in data units called tokens.
Traffic is one way
Pros of ring?
Very fast, no collisions
Cons of ring?
Problems with backbone can bring whole network down
Data passes through every node, network is vulnerable to malfunctions
What is an IP address?
Is an address that a data packet in a network is sent sent to. Each computer on a network has an IP address
Consists of a 32 bit number
What is a packet?
A collection of data forming part of a message. A packet is constructed by the appropriate protocol.
What are protocols?
A set of rules that covers data communication eg. TCP/IP, DNS
Why is the Internet?
A worldwide connection of computer networks
What is need to connect to the Internet?
Modem
Router
What is a modem?
A modem converts analogue signals into digital signals (used by computers) and allows connection to the Internet on the POTS
How does the Internet make use of IP addresses?
Intended uses IP addresses to idnetify connected resources
What is DNS?
Domain name system is a protocol
Which connects IP addresses which are hard to remember because they are numbers, to user-friendly names which are memorable
What does JpG store and how is it compressed?
Storing still images
Lossy compression
What does giF store and how is it compressed?
Bitmapped images
Lossless compression
What is the use of PDF?
Representing documents I the same way no matter what software is being used to display them
What does MP3 store?
Digital audio
Lossy compression
What does MPEG store and how is it compressed?
Videos as movie films
Lossy compression
Why is it important to compress files
Save storage space on media
Reduces transmission times in a network
What is Lossless compression?
Lossless compression doe not store repeated detail
It allows the original file to be reconstructed exactly
No data is lost
What is lossy compression?
Removes data from a file
Data which is removed cannot be recovered
Removes least important detail
