1.5 Data Transmission

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Karteikarten am 1.5 Data Transmission, erstellt von messagekm am 21/03/2014.
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Zusammenfassung der Ressource

Frage Antworten
What is a Computer Network? Computer connected together to share resources and data
What are the features of a LAN? Local Area Network Short distances - eg in a school or typically in one building
What are the features of a WAN? Wide Area Network Longer Distances, Using the Telephone (PSTN) Infrastructure, National, International, Global
What is an NIC? Network Interface Card? HW attached to the processor to enable a connection to a Network (Cabled or Wireless)
In what two ways a can a Network connection be made? Cable or Wireless
What are the feature of a Wired Connection? Uses a Coaxial Cable, Signal deteriorates over distance (300 Metres) and may need boosting by Repeaters
What are the feature of a Wireless Connection? Uses a router to broadcast signal, All enabled devices and pick up the signal. Security needs to be configured. Signal can escape confines of a building.
What is a server on a network? A computer with software which is given a particular Network job to do.
What servers are typical on a lager network? File Server (centrally holding data and SW), A Domain Controller (Responsible for authenticating Logons), Print Server (Managing Print Jobs), Email Server (Email Management)
What is a Modem and What does it do? It enables computer to use the Telephone Network to communicate. The change date from digital to analogue and back again. Computer can only work with data in digital form
What is Serial Transmission of data? Data transmitted one bit (1 or 0) at a time along a wire. Simple and Reliable but SLOW. A USB stick work with Serial Transmission
What is Parallel Transmission of data? Data transmitted along a number of wires (usually 8 to represent a byte). One byte at a time cant be sent. Faster than Serial but can have errors owing to faults on the wires. Hence the need for error checking.
Modes of Transmission. What is SIMPLEX, HALF-DUPLEX and DUPLEX? Simplex - one direction only (Teletext) HALF-DUPLEX - two directions but only one direction at a time (Walkie-Talkie Radio) DUPLEX - Both directions at same time (Telephone call)
What is a Bit Rate? The number of Bits that can be sent in 1 second
Why does a picture take longer to transmit than character based data? The more pixels the are the more data thee is in a picture. Transmitting High resolution takes longer. Lower resolution transmits more quickly. For characters remember 1 character is only 8 bits (1 byte)
What is File Compression? Reducing the amount of data sent by using an algorithm. Shrinking the file size of a picture. And then using an algorithm to restore the compressed data.
What is the difference between Speed of transmission and Rate of transmission. Speed refers to the time takes to transmist data (usually the same whatever method). Rate refers to the amount of data being transfers at a time, eg Bandwidth
What is Streaming of Data? In the context of watching a video it would be viewing the data as it is being received. Time Sensitive Data
Error in Data Transmission - What is Echoing Back? Sending ALL of the data back to the source for comparison
Error in Data Transmission - What is a Checksum? The binary values of blocks of data can be added together. Also the addition of the bytes that rare being sent. The value is calculated at the beginning of sending and also at the end. These are then compared.
Error in Data Transmission - What is a Parity Check? Checking the number of 1's in a byte sent total an EVEN number (for even parity) or and ODD number (for odd parity). May not pick up if there have been two errors so Parity Blocks Can be used.
Error in Data Transmission - What is a Parity Block?
What is Packet Switching? Data is split into a number of smaller Packets (with a label and address) and are sent and then re-assembled at the destination. Allows optimum use of the network. Date is hard to intercept as it is split and following different routes.
What is Packet Switching? Reserving an entire route on the network from source to destination to transmit the data along. Data does not need to be reassembled but large parts of a network can be tied up
What is meant by the term Protocol? Rules which govern the transmission of Data. How data is Routed, How Transmission is going to be Controlled.
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